Methodological principles of radiation diagnostic methods. Topic: Basic methods of radiation diagnostics

2.1. X-RAY DIAGNOSTICS

(RADIOLOGY)

Almost all medical institutions widely use X-ray examination devices. X-ray installations are simple, reliable, and economical. It is these systems that continue to serve as the basis for diagnosing skeletal injuries, diseases of the lungs, kidneys and alimentary canal. In addition, the X-ray method plays an important role in performing various interventional procedures (both diagnostic and therapeutic).

2.1.1. Brief characteristics of X-ray radiation

X-ray radiation is electromagnetic waves (a flow of quanta, photons), the energy of which is located on the energy scale between ultraviolet radiation and gamma radiation (Fig. 2-1). X-ray photons have energies from 100 eV to 250 keV, which corresponds to radiation with a frequency from 3×10 16 Hz to 6×10 19 Hz and a wavelength of 0.005-10 nm. The electromagnetic spectra of X-rays and gamma radiation overlap to a large extent.

Rice. 2-1.Electromagnetic radiation scale

The main difference between these two types of radiation is the way they are generated. X-rays are produced with the participation of electrons (for example, when their flow is slowed down), and gamma rays are produced during the radioactive decay of the nuclei of some elements.

X-rays can be generated when an accelerated flow of charged particles decelerates (the so-called bremsstrahlung) or when high-energy transitions occur in the electron shells of atoms (characteristic radiation). Medical devices use X-ray tubes to generate X-rays (Figure 2-2). Their main components are a cathode and a massive anode. Electrons emitted due to the difference in electrical potential between the anode and cathode are accelerated, reach the anode, and are decelerated when they collide with the material. As a result, X-ray bremsstrahlung occurs. During the collision of electrons with the anode, a second process also occurs - electrons are knocked out from the electron shells of the atoms of the anode. Their places are taken by electrons from other shells of the atom. During this process, a second type of X-ray radiation is generated - the so-called characteristic X-ray radiation, the spectrum of which largely depends on the anode material. Anodes are most often made of molybdenum or tungsten. Special devices are available to focus and filter X-rays to improve the resulting images.

Rice. 2-2.Diagram of the X-ray tube device:

1 - anode; 2 - cathode; 3 - voltage supplied to the tube; 4 - X-ray radiation

The properties of X-rays that determine their use in medicine are penetrating ability, fluorescent and photochemical effects. The penetrating ability of X-rays and their absorption by tissues of the human body and artificial materials are the most important properties that determine their use in radiation diagnostics. The shorter the wavelength, the greater the penetrating power of x-rays.

There are “soft” X-rays with low energy and radiation frequency (according to the longest wavelength) and “hard” X-rays with high photon energy and radiation frequency and a short wavelength. The wavelength of X-ray radiation (accordingly, its “hardness” and penetrating ability) depends on the voltage applied to the X-ray tube. The higher the voltage on the tube, the greater the speed and energy of the electron flow and the shorter the wavelength of the X-rays.

When X-ray radiation penetrating through a substance interacts, qualitative and quantitative changes occur in it. The degree of absorption of X-rays by tissues varies and is determined by the density and atomic weight of the elements that make up the object. The higher the density and atomic weight of the substance that makes up the object (organ) being studied, the more X-rays are absorbed. The human body contains tissues and organs of different densities (lungs, bones, soft tissues, etc.), this explains the different absorption of X-rays. Visualization of internal organs and structures is based on artificial or natural differences in the absorption of X-rays by various organs and tissues.

To register radiation passing through a body, its ability to cause fluorescence of certain compounds and have a photochemical effect on the film is used. For this purpose, special screens for fluoroscopy and photographic films for radiography are used. In modern X-ray machines, special systems of digital electronic detectors - digital electronic panels - are used to record attenuated radiation. In this case, X-ray methods are called digital.

Due to the biological effects of X-rays, it is necessary to protect patients during examination. This is achieved

the shortest possible exposure time, replacement of fluoroscopy with radiography, strictly justified use of ionizing methods, protection by shielding the patient and personnel from exposure to radiation.

2.1.2. Radiography and fluoroscopy

Fluoroscopy and radiography are the main methods of radiographic examination. A number of special devices and methods have been created to study various organs and tissues (Fig. 2-3). Radiography is still very widely used in clinical practice. Fluoroscopy is used less frequently due to the relatively high radiation dose. They are forced to resort to fluoroscopy where radiography or non-ionizing methods for obtaining information are insufficient. In connection with the development of CT, the role of classical layer-by-slice tomography has decreased. The layered tomography technique is used to study the lungs, kidneys and bones where there are no CT rooms.

X-ray (Greek) scopeo- examine, observe) - a study in which an x-ray image is projected onto a fluorescent screen (or a system of digital detectors). The method allows for static as well as dynamic functional studies of organs (for example, fluoroscopy of the stomach, excursion of the diaphragm) and monitoring of interventional procedures (for example, angiography, stenting). Currently, when using digital systems, images are obtained on computer monitors.

The main disadvantages of fluoroscopy include the relatively high radiation dose and difficulties in differentiating “subtle” changes.

Radiography (Greek) greapho- write, depict) - a study in which an X-ray image of an object is obtained, fixed on film (direct radiography) or on special digital devices (digital radiography).

Various types of radiography (survey radiography, targeted radiography, contact radiography, contrast radiography, mammography, urography, fistulography, arthrography, etc.) are used to improve the quality and increase the quantity of diagnostics obtained.

Rice. 2-3.Modern X-ray machine

technical information in each specific clinical situation. For example, contact radiography is used for dental photographs, and contrast radiography is used for excretory urography.

X-ray and fluoroscopy techniques can be used with a vertical or horizontal position of the patient’s body in inpatient or ward settings.

Traditional radiography using x-ray film or digital radiography remains one of the main and widely used research techniques. This is due to the high efficiency, simplicity and information content of the resulting diagnostic images.

When photographing an object from a fluorescent screen onto film (usually small in size - photographic film of a special format), X-ray images are obtained, usually used for mass examinations. This technique is called fluorography. Currently, it is gradually falling out of use due to its replacement by digital radiography.

The disadvantage of any type of x-ray examination is its low resolution when examining low-contrast tissues. Classical tomography, previously used for this purpose, did not give the desired result.

2.2. ULTRASONIC DIAGNOSTICS (SONOGRAPHY, ultrasound)

Ultrasound diagnostics (sonography, ultrasound) is a radiation diagnostic method based on obtaining images of internal organs using ultrasonic waves.

Ultrasound is widely used in diagnosis. Over the past 50 years, the method has become one of the most widespread and important, providing fast, accurate and safe diagnosis of many diseases.

Ultrasound refers to sound waves with a frequency above 20,000 Hz. This is a form of mechanical energy that has a wave nature. Ultrasonic waves propagate in biological media. The speed of propagation of the ultrasonic wave in tissues is constant and amounts to 1540 m/sec. The image is obtained by analyzing the signal (echo signal) reflected from the boundary of two media. In medicine, the most commonly used frequencies are in the range of 2-10 MHz.

Ultrasound is generated by a special sensor with a piezoelectric crystal. Short electrical pulses create mechanical vibrations in the crystal, resulting in the generation of ultrasonic radiation. The frequency of ultrasound is determined by the resonant frequency of the crystal. The reflected signals are recorded, analyzed and displayed visually on the instrument screen, creating images of the structures being studied. Thus, the sensor works sequentially as an emitter and then as a receiver of ultrasonic waves. The operating principle of the ultrasonic system is shown in Fig. 2-4.

Rice. 2-4.Operating principle of the ultrasonic system

The greater the acoustic resistance, the greater the reflection of ultrasound. Air does not conduct sound waves, so to improve signal penetration at the air/skin interface, a special ultrasound gel is applied to the sensor. This eliminates the air gap between the patient's skin and the sensor. Severe artifacts during the study can arise from structures containing air or calcium (lung fields, bowel loops, bones and calcifications). For example, when examining the heart, the latter can be almost completely covered by tissues that reflect or do not conduct ultrasound (lungs, bones). In this case, examination of the organ is possible only through small areas on

the surface of the body where the organ under study is in contact with soft tissues. This area is called the ultrasound “window”. If the ultrasound “window” is poor, the study may be impossible or uninformative.

Modern ultrasound machines are complex digital devices. They use real-time sensors. The images are dynamic, on them you can observe such fast processes as breathing, heart contractions, pulsation of blood vessels, movement of valves, peristalsis, and fetal movements. The position of the sensor, connected to the ultrasonic device with a flexible cable, can be changed in any plane and at any angle. The analog electrical signal generated in the sensor is digitized and a digital image is created.

The Doppler technique is very important in ultrasound examination. Doppler described the physical effect according to which the frequency of sound generated by a moving object changes when it is perceived by a stationary receiver, depending on the speed, direction and nature of the movement. The Doppler method is used to measure and visualize the speed, direction and nature of blood movement in the vessels and chambers of the heart, as well as the movement of any other fluids.

During Doppler examination of blood vessels, continuous-wave or pulsed ultrasound radiation passes through the area being examined. When an ultrasound beam crosses a vessel or chamber of the heart, the ultrasound is partially reflected by red blood cells. So, for example, the frequency of the reflected echo signal from blood moving towards the sensor will be higher than the original frequency of the waves emitted by the sensor. Conversely, the frequency of the reflected echo signal from blood moving away from the sensor will be lower. The difference between the frequency of the received echo signal and the frequency of the ultrasound generated by the transducer is called the Doppler shift. This frequency shift is proportional to the speed of blood flow. The ultrasound device automatically converts the Doppler shift into relative blood flow velocity.

Studies that combine real-time two-dimensional ultrasound and pulsed Doppler ultrasound are called duplex. In a duplex study, the direction of the Doppler beam is superimposed on a two-dimensional B-mode image.

Modern development of duplex research technology has led to the emergence of color Doppler mapping of blood flow. Within the control volume, the colored blood flow is superimposed on the 2D image. In this case, blood is displayed in color, and motionless tissue is displayed in a gray scale. When blood moves towards the sensor, red-yellow colors are used, when moving away from the sensor, blue-cyan colors are used. This color image does not carry additional information, but gives a good visual idea of ​​the nature of blood movement.

In most cases, for the purpose of ultrasound, it is sufficient to use transcutaneous probes. However, in some cases it is necessary to bring the sensor closer to the object. For example, in large patients, probes placed in the esophagus (transesophageal echocardiography) are used to study the heart; in other cases, intrarectal or intravaginal probes are used to obtain high-quality images. During the operation, they resort to the use of surgical sensors.

In recent years, three-dimensional ultrasound has been increasingly used. The range of ultrasound systems is very wide - there are portable devices, devices for intraoperative ultrasound and expert-class ultrasound systems (Fig. 2-5).

In modern clinical practice, the method of ultrasound examination (sonography) is extremely widespread. This is explained by the fact that when using the method there is no ionizing radiation, it is possible to conduct functional and stress tests, the method is informative and relatively inexpensive, the devices are compact and easy to use.

Rice. 2-5.Modern ultrasound machine

However, the sonography method has its limitations. These include a high frequency of artifacts in the image, a small depth of signal penetration, a small field of view, and a high dependence of the interpretation of results on the operator.

With the development of ultrasonic equipment, the information content of this method is increasing.

2.3. COMPUTED TOMOGRAPHY (CT)

CT is an x-ray examination method based on obtaining layer-by-layer images in the transverse plane and their computer reconstruction.

The creation of CT machines is the next revolutionary step in obtaining diagnostic images after the discovery of X-rays. This is due not only to the versatility and unsurpassed resolution of the method when examining the whole body, but also to new imaging algorithms. Currently, all devices associated with obtaining images use, to one degree or another, the technical techniques and mathematical methods that formed the basis of CT.

CT has no absolute contraindications to its use (except for restrictions associated with ionizing radiation) and can be used for emergency diagnostics, screening, and also as a method of clarifying diagnostics.

The main contribution to the creation of computed tomography was made by the British scientist Godfrey Hounsfield in the late 60s. XX century.

At first, computed tomographs were divided into generations depending on how the X-ray tube-detector system was designed. Despite numerous differences in structure, they were all called “step” tomographs. This was due to the fact that after each cross-section the tomograph stopped, the table with the patient took a “step” of several millimeters, and then the next section was performed.

In 1989, spiral computed tomography (SCT) appeared. In the case of SCT, an X-ray tube with detectors constantly rotates around a continuously moving table with a patient

volume. This allows not only to reduce the examination time, but also to avoid the limitations of the “step-by-step” technique - skipping sections during the examination due to different depths of breath holding by the patient. The new software additionally made it possible to change the slice width and image restoration algorithm after the end of the study. This made it possible to obtain new diagnostic information without repeat examination.

From this point on, CT became standardized and universal. It was possible to synchronize the introduction of a contrast agent with the beginning of table movement during SCT, which led to the creation of CT angiography.

In 1998, multislice CT (MSCT) appeared. Systems were created with not one (as with SCT), but with 4 rows of digital detectors. Since 2002, tomographs with 16 rows of digital elements in the detector began to be used, and since 2003, the number of rows of elements reached 64. In 2007, MSCT with 256 and 320 rows of detector elements appeared.

With such tomographs it is possible to obtain hundreds and thousands of tomograms in just a few seconds with a thickness of each slice of 0.5-0.6 mm. This technical improvement made it possible to perform the study even on patients connected to an artificial respiration apparatus. In addition to speeding up the examination and improving its quality, such a complex problem as visualization of the coronary vessels and heart cavities using CT was solved. It became possible to study the coronary vessels, the volume of cavities and cardiac function, and myocardial perfusion in one 5-20 second study.

A schematic diagram of the CT device is shown in Fig. 2-6, and the appearance is in Fig. 2-7.

The main advantages of modern CT include: the speed of obtaining images, the layer-by-layer (tomographic) nature of images, the ability to obtain sections of any orientation, high spatial and temporal resolution.

The disadvantages of CT are the relatively high (compared to radiography) radiation dose, the possibility of the appearance of artifacts from dense structures, movements, and relatively low soft tissue contrast resolution.

Rice. 2-6.MSCT device diagram

Rice. 2-7.Modern 64-spiral computed tomograph

2.4. MAGNETIC RESONANCE

TOMOGRAPHY (MRI)

Magnetic resonance imaging (MRI) is a method of radiation diagnostics based on obtaining layer-by-layer and volumetric images of organs and tissues of any orientation using the phenomenon of nuclear magnetic resonance (NMR). The first work on imaging using NMR appeared in the 70s. last century. To date, this method of medical imaging has changed beyond recognition and continues to evolve. Hardware and software are being improved, and image acquisition techniques are being improved. Previously, the use of MRI was limited to the study of the central nervous system. Now the method is successfully used in other areas of medicine, including studies of blood vessels and the heart.

After the inclusion of NMR among the methods of radiation diagnostics, the adjective “nuclear” was no longer used so as not to cause associations in patients with nuclear weapons or nuclear energy. Therefore, today the term “magnetic resonance imaging” (MRI) is officially used.

NMR is a physical phenomenon based on the properties of certain atomic nuclei placed in a magnetic field to absorb external energy in the radio frequency (RF) range and emit it after the RF pulse is removed. The strength of the constant magnetic field and the frequency of the radio frequency pulse strictly correspond to each other.

Important nuclei for use in magnetic resonance imaging are 1H, 13C, 19F, 23Na and 31P. All of them have magnetic properties, which distinguishes them from non-magnetic isotopes. Hydrogen protons (1H) are the most abundant in the body. Therefore, for MRI, it is the signal from hydrogen nuclei (protons) that is used.

Hydrogen nuclei can be thought of as small magnets (dipoles) having two poles. Each proton rotates around its own axis and has a small magnetic moment (magnetization vector). The rotating magnetic moments of nuclei are called spins. When such nuclei are placed in an external magnetic field, they can absorb electromagnetic waves of certain frequencies. This phenomenon depends on the type of nuclei, the strength of the magnetic field, and the physical and chemical environment of the nuclei. With this behavior

The motion of the nucleus can be compared to a rotating top. Under the influence of a magnetic field, the rotating core undergoes complex motion. The core rotates around its axis, and the axis of rotation itself makes cone-shaped circular movements (precesses), deviating from the vertical direction.

In an external magnetic field, nuclei can be either in a stable energy state or in an excited state. The energy difference between these two states is so small that the number of nuclei at each of these levels is almost identical. Therefore, the resulting NMR signal, which depends precisely on the difference in the populations of these two levels by protons, will be very weak. To detect this macroscopic magnetization, it is necessary to deviate its vector from the axis of a constant magnetic field. This is achieved using a pulse of external radio frequency (electromagnetic) radiation. When the system returns to an equilibrium state, the absorbed energy (MR signal) is emitted. This signal is recorded and used to construct MR images.

Special (gradient) coils located inside the main magnet create small additional magnetic fields so that the field strength increases linearly in one direction. By transmitting radiofrequency pulses with a predetermined narrow frequency range, it is possible to obtain MR signals only from a selected layer of tissue. The orientation of the magnetic field gradients and, accordingly, the direction of the cuts can be easily specified in any direction. The signals received from each volumetric image element (voxel) have their own, unique, recognizable code. This code is the frequency and phase of the signal. Based on this data, two- or three-dimensional images can be constructed.

To obtain a magnetic resonance signal, combinations of radio frequency pulses of various durations and shapes are used. By combining different pulses, so-called pulse sequences are formed, which are used to obtain images. Special pulse sequences include MR hydrography, MR myelography, MR cholangiography and MR angiography.

Tissues with large total magnetic vectors will induce a strong signal (look bright), and tissues with small

with magnetic vectors - a weak signal (they look dark). Anatomical areas with a low number of protons (eg air or compact bone) induce a very weak MR signal and thus always appear dark in the image. Water and other liquids have a strong signal and appear bright in the image, with varying intensities. Soft tissue images also have different signal intensities. This is due to the fact that, in addition to proton density, the nature of the signal intensity in MRI is determined by other parameters. These include: the time of spin-lattice (longitudinal) relaxation (T1), spin-spin (transverse) relaxation (T2), motion or diffusion of the medium under study.

Tissue relaxation times - T1 and T2 - are constant. In MRI, the terms “T1-weighted image”, “T2-weighted image”, “proton-weighted image” are used to indicate that the differences between tissue images are predominantly due to the predominant action of one of these factors.

By adjusting the parameters of the pulse sequences, the radiographer or physician can influence the contrast of the images without resorting to the use of contrast agents. Therefore, in MR imaging there is much more opportunity to change the contrast in images than in radiography, CT or ultrasound. However, the introduction of special contrast agents can further alter the contrast between normal and pathological tissues and improve the quality of imaging.

The schematic diagram of the MR system and the appearance of the device are shown in Fig. 2-8

and 2-9.

Typically, MRI scanners are classified based on the strength of the magnetic field. Magnetic field strength is measured in teslas (T) or gauss (1T = 10,000 gauss). The strength of the Earth's magnetic field ranges from 0.7 gauss at the poles to 0.3 gauss at the equator. For cli-

Rice. 2-8.MRI device diagram

Rice. 2-9.Modern MRI system with a field of 1.5 Tesla

nical MRI uses magnets with fields from 0.2 to 3 Tesla. Currently, MR systems with fields of 1.5 and 3 Tesla are most often used for diagnostics. Such systems account for up to 70% of the world's equipment fleet. There is no linear relationship between field strength and image quality. However, devices with such field strength provide better image quality and have a greater number of programs used in clinical practice.

The main area of ​​application of MRI became the brain and then the spinal cord. Brain tomograms provide excellent images of all brain structures without the need for additional contrast. Thanks to the technical ability of the method to obtain images in all planes, MRI has revolutionized the study of the spinal cord and intervertebral discs.

Currently, MRI is increasingly used to study joints, pelvic organs, mammary glands, heart and blood vessels. For these purposes, additional special coils and mathematical methods for constructing images have been developed.

A special technique allows you to record images of the heart in different phases of the cardiac cycle. If the study is carried out at

synchronization with an ECG, images of a functioning heart can be obtained. This study is called cine MRI.

Magnetic resonance spectroscopy (MRS) is a non-invasive diagnostic method that allows you to qualitatively and quantitatively determine the chemical composition of organs and tissues using nuclear magnetic resonance and the phenomenon of chemical shift.

MR spectroscopy is most often performed to obtain signals from phosphorus and hydrogen nuclei (protons). However, due to technical difficulties and time-consuming procedure, it is still rarely used in clinical practice. It should not be forgotten that the increasing use of MRI requires special attention to patient safety issues. When examined using MR spectroscopy, the patient is not exposed to ionizing radiation, but is exposed to electromagnetic and radio frequency radiation. Metal objects (bullets, fragments, large implants) and all electronic-mechanical devices (for example, heart pacemaker) located in the body of the person being examined can harm the patient due to displacement or disruption (cessation) of normal operation.

Many patients experience a fear of closed spaces - claustrophobia, which leads to the inability to perform the examination. Thus, all patients should be informed about the possible undesirable consequences of the study and the nature of the procedure, and attending physicians and radiologists are required to question the patient before the study regarding the presence of the above items, injuries and operations. Before the study, the patient must completely change into a special suit to prevent metal items from getting into the magnet channel from clothing pockets.

It is important to know the relative and absolute contraindications to the study.

Absolute contraindications to the study include conditions in which its conduct creates a life-threatening situation for the patient. This category includes all patients with the presence of electronic-mechanical devices in the body (pacemakers), and patients with the presence of metal clips on the arteries of the brain. Relative contraindications to the study include conditions that can create certain dangers and difficulties when performing MRI, but in most cases it is still possible. Such contraindications are

the presence of hemostatic staples, clamps and clips of other localization, decompensation of heart failure, the first trimester of pregnancy, claustrophobia and the need for physiological monitoring. In such cases, the decision on the possibility of performing an MRI is made on a case-by-case basis based on the ratio of the magnitude of the possible risk and the expected benefit from the study.

Most small metal objects (artificial teeth, surgical suture material, some types of artificial heart valves, stents) are not a contraindication to the study. Claustrophobia is an obstacle to research in 1-4% of cases.

Like other radiation diagnostic techniques, MRI is not without its drawbacks.

Significant disadvantages of MRI include the relatively long examination time, the inability to accurately detect small stones and calcifications, the complexity of the equipment and its operation, and special requirements for the installation of devices (protection from interference). MRI is difficult to evaluate patients who require life-sustaining equipment.

2.5. RADIONUCLIDE DIAGNOSTICS

Radionuclide diagnostics or nuclear medicine is a method of radiation diagnostics based on recording radiation from artificial radioactive substances introduced into the body.

For radionuclide diagnostics, a wide range of labeled compounds (radiopharmaceuticals (RP)) and methods for their registration with special scintillation sensors are used. The energy of absorbed ionizing radiation excites flashes of visible light in the sensor crystal, each of which is amplified by photomultipliers and converted into a current pulse.

Signal power analysis allows us to determine the intensity and spatial position of each scintillation. These data are used to reconstruct a two-dimensional image of radiopharmaceutical propagation. The image can be presented directly on the monitor screen, on photo or multi-format film, or recorded on computer media.

There are several groups of radiodiagnostic devices depending on the method and type of radiation registration:

Radiometers are instruments for measuring radioactivity throughout the body;

Radiographs are instruments for recording the dynamics of changes in radioactivity;

Scanners - systems for recording the spatial distribution of radiopharmaceuticals;

Gamma cameras are devices for static and dynamic recording of the volumetric distribution of a radioactive tracer.

In modern clinics, the majority of devices for radionuclide diagnostics are gamma cameras of various types.

Modern gamma cameras are a complex consisting of 1-2 large-diameter detector systems, a table for positioning the patient and a computer system for storing and processing images (Fig. 2-10).

The next step in the development of radionuclide diagnostics was the creation of a rotational gamma camera. With the help of these devices, it was possible to apply a layer-by-layer technique for studying the distribution of isotopes in the body - single-photon emission computed tomography (SPECT).

Rice. 2-10.Gamma camera device diagram

SPECT uses rotating gamma cameras with one, two or three detectors. Mechanical tomography systems allow the detectors to be rotated around the patient's body in different orbits.

The spatial resolution of modern SPECT is about 5-8 mm. The second condition for performing a radioisotope study, in addition to the availability of special equipment, is the use of special radioactive tracers - radiopharmaceuticals (RP), which are introduced into the patient’s body.

A radiopharmaceutical is a radioactive chemical compound with known pharmacological and pharmacokinetic characteristics. Radiopharmaceuticals used in medical diagnostics are subject to fairly strict requirements: affinity for organs and tissues, ease of preparation, short half-life, optimal gamma radiation energy (100-300 keV) and low radiotoxicity at relatively high permissible doses. An ideal radiopharmaceutical should be delivered only to the organs or pathological foci intended for research.

Understanding the mechanisms of radiopharmaceutical localization serves as the basis for adequate interpretation of radionuclide studies.

The use of modern radioactive isotopes in medical diagnostic practice is safe and harmless. The amount of active substance (isotope) is so small that when introduced into the body it does not cause physiological effects or allergic reactions. In nuclear medicine, radiopharmaceuticals that emit gamma rays are used. Sources of alpha (helium nuclei) and beta particles (electrons) are currently not used in diagnostics due to the high degree of absorption by tissues and high radiation exposure.

The most used isotope in clinical practice is technetium-99t (half-life - 6 hours). This artificial radionuclide is obtained immediately before the study from special devices (generators).

A radiodiagnostic image, regardless of its type (static or dynamic, planar or tomographic), always reflects the specific function of the organ being examined. Essentially, it is a representation of functioning tissue. It is in the functional aspect that the fundamental distinguishing feature of radionuclide diagnostics from other imaging methods lies.

Radiopharmaceuticals are usually administered intravenously. For pulmonary ventilation studies, the drug is administered by inhalation.

One of the new tomographic radioisotope techniques in nuclear medicine is positron emission tomography (PET).

The PET method is based on the property of some short-lived radionuclides to emit positrons during decay. A positron is a particle equal in mass to an electron, but having a positive charge. A positron, having flown 1-3 mm in matter and lost the kinetic energy received at the moment of formation in collisions with atoms, annihilates to form two gamma quanta (photons) with an energy of 511 keV. These quanta scatter in opposite directions. Thus, the decay point lies on a straight line - the trajectory of two annihilated photons. Two detectors located opposite each other record the combined annihilation photons (Fig. 2-11).

PET allows for quantitative assessment of radionuclide concentrations and has greater capabilities for studying metabolic processes than scintigraphy performed using gamma cameras.

For PET, isotopes of elements such as carbon, oxygen, nitrogen, and fluorine are used. Radiopharmaceuticals labeled with these elements are natural metabolites of the body and are included in the metabolism

Rice. 2-11.PET device diagram

substances.

As a result, it is possible to study processes occurring at the cellular level.

Despite the fact that the first PET systems appeared in the mid-twentieth century, their clinical use is hampered by certain limitations. These are technical difficulties that arise when setting up accelerators in clinics for the production of short-lived isotopes, their high cost, and difficulty in interpreting the results. One of the limitations - poor spatial resolution - was overcome by combining the PET system with MSCT, which, however, makes the system even more expensive (Fig. 2-12). In this regard, PET studies are carried out according to strict indications when other methods are ineffective.

The main advantages of the radionuclide method are its high sensitivity to various types of pathological processes, the ability to assess metabolism and tissue viability.

The general disadvantages of radioisotope methods include low spatial resolution. The use of radioactive drugs in medical practice is associated with difficulties in their transportation, storage, packaging and administration to patients.

Rice. 2-12.Modern PET-CT system

The construction of radioisotope laboratories (especially for PET) requires special premises, security, alarms and other precautions.

2.6. ANGIOGRAPHY

Angiography is a method of x-ray examination associated with the direct introduction of a contrast agent into vessels for the purpose of studying them.

Angiography is divided into arteriography, venography and lymphography. The latter, due to the development of ultrasound, CT and MRI methods, is currently practically not used.

Angiography is performed in specialized X-ray rooms. These rooms meet all the requirements for operating rooms. For angiography, specialized X-ray machines (angiographic units) are used (Fig. 2-13).

The administration of a contrast agent into the vascular bed is carried out by injection with a syringe or (more often) with a special automatic injector after puncture of the vessels.

Rice. 2-13.Modern angiography unit

The main method of vascular catheterization is the Seldinger vascular catheterization technique. To perform angiography, a certain amount of contrast agent is injected into a vessel through a catheter and the passage of the drug through the vessels is recorded.

A variant of angiography is coronary angiography (CAG) - a technique for studying the coronary vessels and chambers of the heart. This is a complex research technique that requires special training of the radiologist and sophisticated equipment.

Currently, diagnostic angiography of peripheral vessels (for example, aortography, angiopulmonography) is used less and less. With the availability of modern ultrasound machines in clinics, CT and MRI diagnostics of pathological processes in blood vessels is increasingly carried out using minimally invasive (CT angiography) or non-invasive (ultrasound and MRI) techniques. In turn, with angiography, minimally invasive surgical procedures (recanalization of the vascular bed, balloon angioplasty, stenting) are increasingly being performed. Thus, the development of angiography led to the birth of interventional radiology.

2.7 INTERVENTIONAL RADIOLOGY

Interventional radiology is a field of medicine based on the use of radiation diagnostic methods and special instruments to perform minimally invasive interventions for the purpose of diagnosing and treating diseases.

Interventional interventions have become widespread in many areas of medicine, as they can often replace major surgical interventions.

The first percutaneous treatment for peripheral artery stenosis was performed by American physician Charles Dotter in 1964. In 1977, Swiss physician Andreas Gruntzig designed a balloon catheter and performed a procedure to dilate a stenotic coronary artery. This method became known as balloon angioplasty.

Balloon angioplasty of the coronary and peripheral arteries is currently one of the main methods of treating stenosis and occlusion of the arteries.

In case of recurrence of stenoses, this procedure can be repeated many times. To prevent repeated stenoses, at the end of the last century they began to use endo-

vascular prostheses - stents. A stent is a tubular metal structure that is installed in a narrowed area after balloon dilatation. An extended stent prevents re-stenosis from occurring.

The technique of installing special filters in the inferior vena cava (cava filters) has acquired particular importance. This is necessary to prevent emboli from entering the pulmonary vessels during thrombosis of the veins of the lower extremities. The vena cava filter is a mesh structure that, opening in the lumen of the inferior vena cava, traps ascending blood clots.

Another endovascular intervention in demand in clinical practice is embolization (blockage) of blood vessels. Embolization is used to stop internal bleeding, treat pathological vascular anastomosis, aneurysms, or to close vessels feeding a malignant tumor. Currently, effective artificial materials, removable balloons and microscopic steel coils are used for embolization. Embolization is usually performed selectively so as not to cause ischemia of surrounding tissues.

Rice. 2-14.Scheme of balloon angioplasty and stenting

Interventional radiology also includes drainage of abscesses and cysts, contrasting of pathological cavities through fistulous tracts, restoration of patency of the urinary tract in case of urinary disorders, bougienage and balloon plasty for strictures (narrowings) of the esophagus and bile ducts, percutaneous thermal or cryodestruction of malignant tumors and other interventions.

After identifying a pathological process, it is often necessary to resort to an interventional radiology option such as a puncture biopsy. Knowledge of the morphological structure of the formation allows you to choose adequate treatment tactics. A puncture biopsy is performed under X-ray, ultrasound or CT control.

Currently, interventional radiology is actively developing and in many cases makes it possible to avoid major surgical interventions.

2.8 CONTRAST AGENTS FOR RADIATION DIAGNOSTICS

Low contrast between adjacent objects or similar densities of adjacent tissues (eg, blood, vessel wall, and thrombus) make image interpretation difficult. In these cases, radiological diagnostics often resort to artificial contrast.

An example of enhancing the contrast of images of the organs being studied is the use of barium sulfate to study the organs of the digestive canal. Such contrasting was first performed in 1909.

It was more difficult to create contrast agents for intravascular administration. For this purpose, after much experimentation with mercury and lead, soluble iodine compounds began to be used. The first generations of radiocontrast agents were imperfect. Their use caused frequent and severe (even fatal) complications. But already in the 20-30s. XX century A number of safer water-soluble iodine-containing drugs for intravenous administration have been created. The widespread use of drugs in this group began in 1953, when a drug was synthesized whose molecule consisted of three iodine atoms (diatrizoate).

In 1968, substances that had low osmolarity (they did not dissociate into anion and cation in solution) were developed - nonionic contrast agents.

Modern radiocontrast agents are triiodine-substituted compounds containing three or six iodine atoms.

There are drugs for intravascular, intracavitary and subarachnoid administration. You can also inject a contrast agent into the cavities of the joints, into the cavitary organs and under the membranes of the spinal cord. For example, the introduction of contrast through the uterine body cavity into the tubes (hysterosalpingography) allows one to evaluate the inner surface of the uterine cavity and the patency of the fallopian tubes. In neurological practice, in the absence of MRI, the myelography technique is used - the introduction of a water-soluble contrast agent under the membranes of the spinal cord. This allows us to assess the patency of the subarachnoid spaces. Other artificial contrast techniques include angiography, urography, fistulography, herniography, sialography, and arthrography.

After a rapid (bolus) intravenous injection of contrast agent, it reaches the right side of the heart, then the bolus passes through the vascular bed of the lungs and reaches the left side of the heart, then the aorta and its branches. Rapid diffusion of the contrast agent from the blood into the tissue occurs. During the first minute after a rapid injection, a high concentration of contrast agent remains in the blood and blood vessels.

Intravascular and intracavitary administration of contrast agents containing iodine in their molecule, in rare cases, can have an adverse effect on the body. If such changes manifest themselves as clinical symptoms or alter the patient's laboratory values, they are called adverse reactions. Before examining a patient using contrast agents, it is necessary to find out whether he has allergic reactions to iodine, chronic renal failure, bronchial asthma and other diseases. The patient should be warned about the possible reaction and the benefits of such a study.

In the event of a reaction to the administration of a contrast agent, office personnel are required to act in accordance with special instructions for combating anaphylactic shock to prevent severe complications.

Contrast agents are also used in MRI. Their use began in recent decades, after the intensive introduction of the method into the clinic.

The use of contrast agents in MRI is aimed at changing the magnetic properties of tissues. This is their significant difference from iodine-containing contrast agents. While X-ray contrast agents significantly attenuate the penetrating radiation, MRI drugs lead to changes in the characteristics of the surrounding tissue. They are not visualized on tomograms, like X-ray contrast agents, but they make it possible to identify hidden pathological processes due to changes in magnetic indicators.

The mechanism of action of these agents is based on changes in the relaxation time of a tissue area. Most of these drugs are gadolinium-based. Contrast agents based on iron oxide are used much less frequently. These substances have different effects on signal intensity.

Positive ones (shortening T1 relaxation time) are usually based on gadolinium (Gd), and negative ones (shortening T2 time) are based on iron oxide. Gadolinium-based contrast agents are considered safer compounds than iodine-containing ones. There are only isolated reports of serious anaphylactic reactions to these substances. Despite this, careful monitoring of the patient after the injection and the availability of accessible resuscitation equipment are necessary. Paramagnetic contrast agents are distributed in the intravascular and extracellular spaces of the body and do not pass through the blood-brain barrier (BBB). Therefore, in the central nervous system, only areas that lack this barrier are normally contrasted, such as the pituitary gland, pituitary infundibulum, cavernous sinuses, dura mater, and mucous membranes of the nose and paranasal sinuses. Damage and destruction of the BBB lead to the penetration of paramagnetic contrast agents into the intercellular space and a local change in T1 relaxation. This is observed in a number of pathological processes in the central nervous system, such as tumors, metastases, cerebrovascular accidents, and infections.

In addition to MRI studies of the central nervous system, contrast is used to diagnose diseases of the musculoskeletal system, heart, liver, pancreas, kidneys, adrenal glands, pelvic organs and mammary glands. These studies are carried out significantly

significantly less often than with CNS pathology. To perform MR angiography and study organ perfusion, it is necessary to administer a contrast agent using a special non-magnetic injector.

In recent years, the feasibility of using contrast agents for ultrasound examinations has been studied.

To increase the echogenicity of the vascular bed or parenchymal organ, an ultrasound contrast agent is injected intravenously. These can be suspensions of solid particles, emulsions of liquid droplets, and most often, gas microbubbles placed in various shells. Like other contrast agents, ultrasound contrast agents should have low toxicity and be rapidly eliminated from the body. The first generation drugs did not pass through the capillary bed of the lungs and were destroyed in it.

The contrast agents currently used enter the systemic circulation, which makes it possible to use them to improve the quality of images of internal organs, enhance the Doppler signal and study perfusion. There is currently no final opinion on the advisability of using ultrasound contrast agents.

Adverse reactions during the administration of contrast media occur in 1-5% of cases. The vast majority of adverse reactions are mild and do not require special treatment.

Particular attention should be paid to the prevention and treatment of severe complications. The incidence of such complications is less than 0.1%. The greatest danger is the development of anaphylactic reactions (idiosyncrasy) with the administration of iodine-containing substances and acute renal failure.

Reactions to the administration of contrast agents can be divided into mild, moderate and severe.

With mild reactions, the patient experiences a feeling of heat or chills, and slight nausea. There is no need for therapeutic measures.

With moderate reactions, the above symptoms may also be accompanied by a decrease in blood pressure, the occurrence of tachycardia, vomiting, and urticaria. It is necessary to provide symptomatic medical care (usually the administration of antihistamines, antiemetics, sympathomimetics).

In severe reactions, anaphylactic shock may occur. Urgent resuscitation measures are necessary

ties aimed at maintaining the activity of vital organs.

The following categories of patients are at increased risk. These are the patients:

With severe renal and liver dysfunction;

With a burdened allergic history, especially those who have previously had adverse reactions to contrast agents;

With severe heart failure or pulmonary hypertension;

With severe dysfunction of the thyroid gland;

With severe diabetes mellitus, pheochromocytoma, myeloma.

Young children and elderly people are also considered to be at risk for the development of adverse reactions.

The physician prescribing the study must carefully assess the risk/benefit ratio when performing studies with contrast and take the necessary precautions. A radiologist performing a study on a patient with a high risk of adverse reactions to a contrast agent is obliged to warn the patient and the attending physician about the dangers of using contrast agents and, if necessary, replace the study with another that does not require contrast.

The X-ray room must be equipped with everything necessary to carry out resuscitation measures and combat anaphylactic shock.

Radiation diagnostics and radiation therapy are components of medical radiology (as this discipline is commonly called abroad).

Radiation diagnostics is a practical discipline that studies the use of various radiations in order to recognize numerous diseases, to study the morphology and function of normal and pathological human organs and systems. Radiation diagnostics includes: radiology, including computed tomography (CT); radionuclide diagnostics, ultrasound diagnostics, magnetic resonance imaging (MRI), medical thermography and interventional radiology associated with the performance of diagnostic and therapeutic procedures under the control of radiation research methods.

The role of radiation diagnostics in general and in dentistry in particular cannot be overestimated. Radiation diagnostics is characterized by a number of features. Firstly, it has widespread use both in somatic diseases and in dentistry. In the Russian Federation, more than 115 million x-ray examinations, more than 70 million ultrasound examinations and more than 3 million radionuclide examinations are performed annually. Secondly, radiation diagnostics is informative. With its help, 70-80% of clinical diagnoses are established or supplemented. Radiation diagnostics is used for 2000 different diseases. Dental examinations account for 21% of all x-ray examinations in the Russian Federation and almost 31% in the Omsk region. Another feature is that the equipment used in radiation diagnostics is expensive, especially computer and magnetic resonance imaging scanners. Their cost exceeds 1 - 2 million dollars. Abroad, due to the high price of equipment, radiation diagnostics (radiology) is the most financially intensive branch of medicine. Another feature of radiation diagnostics is that radiology and radionuclide diagnostics, not to mention radiation therapy, pose a radiation hazard to the personnel of these services and patients. This circumstance obliges doctors of all specialties, including dentists, to take this fact into account when prescribing X-ray and radiological examinations.

Radiation therapy is a practical discipline that studies the use of ionizing radiation for therapeutic purposes. Currently, radiation therapy has a large arsenal of quantum and corpuscular radiation sources used in oncology and in the treatment of non-tumor diseases.

Currently, no medical disciplines can do without radiation diagnostics and radiation therapy. There is practically no clinical specialty in which radiation diagnostics and radiation therapy are not associated with the diagnosis and treatment of various diseases.

Dentistry is one of those clinical disciplines where x-ray examination occupies the main place in the diagnosis of diseases of the dental system.

Radiation diagnostics uses 5 types of radiation, which, based on their ability to cause ionization of the environment, are classified as ionizing or non-ionizing radiation. Ionizing radiation includes X-rays and radionuclide radiation. Non-ionizing radiation includes ultrasonic, magnetic, radio frequency, and infrared radiation. However, when using these radiations, single acts of ionization may occur in atoms and molecules, which, however, do not cause any disturbances in human organs and tissues and are not dominant in the process of interaction of radiation with matter.

Basic physical characteristics of radiation

X-ray radiation is an electromagnetic vibration artificially created in special tubes of X-ray machines. This radiation was discovered by Wilhelm Conrad Roentgen in November 1895. X-rays belong to the invisible spectrum of electromagnetic waves with wavelengths ranging from 15 to 0.03 angstroms. The energy of the quanta, depending on the power of the equipment, ranges from 10 to 300 or more KeV. The speed of propagation of X-ray quanta is 300,000 km/sec.

X-rays have certain properties that determine their use in medicine for the diagnosis and treatment of various diseases. The first property is penetrating ability, the ability to penetrate solid and opaque bodies. The second property is their absorption in tissues and organs, which depends on the specific gravity and volume of the tissues. The denser and more voluminous the fabric, the greater the absorption of rays. Thus, the specific gravity of air is 0.001, fat 0.9, soft tissue 1.0, bone tissue 1.9. Naturally, bones will have the greatest X-ray absorption. The third property of X-rays is their ability to cause the glow of fluorescent substances, which is used when conducting transillumination behind the screen of an X-ray diagnostic apparatus. The fourth property is photochemical, due to which an image is obtained on X-ray photographic film. The last, fifth property is the biological effect of X-rays on the human body, which will be the subject of a separate lecture.

X-ray research methods are performed using an X-ray machine, the device of which includes 5 main parts:

• - X-ray emitter (X-ray tube with cooling system);
• - power supply device (transformer with electric current rectifier);
• - radiation receiver (fluorescent screen, film cassettes, semiconductor sensors);
• - tripod device and table for positioning the patient;
• - Remote Control.

The main part of any X-ray diagnostic apparatus is the X-ray tube, which consists of two electrodes: the cathode and the anode. A direct electric current is supplied to the cathode, which glows the cathode filament. When a high voltage is applied to the anode, electrons, as a result of a potential difference, fly from the cathode with high kinetic energy and are decelerated at the anode. When electrons are decelerated, X-rays are formed - bremsstrahlung rays emerging from the X-ray tube at a certain angle. Modern X-ray tubes have a rotating anode, the speed of which reaches 3000 revolutions per minute, which significantly reduces the heating of the anode and increases the power and service life of the tube.

The X-ray method in dentistry began to be used shortly after the discovery of X-rays. Moreover, it is believed that the first X-ray photograph in Russia (in Riga) captured the jaws of a sawfish in 1896. In January 1901, an article appeared on the role of radiography in dental practice. In general, dental radiology is one of the earliest branches of medical radiology. It began to develop in Russia when the first X-ray rooms appeared. The first specialized X-ray room at the Dental Institute in Leningrad was opened in 1921. In Omsk, general purpose X-ray rooms (where dental photographs were also taken) opened in 1924.

The X-ray method includes the following techniques: fluoroscopy, that is, obtaining an image on a fluorescent screen; radiography - obtaining an image on x-ray film placed in a radiolucent cassette, where it is protected from ordinary light. These methods are the main ones. Additional ones include: tomography, fluorography, X-ray densitometry, etc.

Tomography - obtaining layer-by-layer images on X-ray film. Fluorography is the production of a smaller X-ray image (72×72 mm or 110×110 mm) as a result of photographic transfer of the image from a fluorescent screen.

The X-ray method also includes special, radiopaque studies. When conducting these studies, special techniques and devices are used to obtain x-ray images, and they are called radiopaque because the study uses various contrast agents that block x-rays. Contrast techniques include: angio-, lympho-, uro-, cholecystography.

The X-ray method also includes computed tomography (CT, RCT), which was developed by the English engineer G. Hounsfield in 1972. For this discovery, he and another scientist, A. Cormack, received the Nobel Prize in 1979. Computed tomographs are currently available in Omsk: in the Diagnostic Center, Regional Clinical Hospital, Irtyshka Central Basin Clinical Hospital. The principle of X-ray CT is based on the layer-by-layer examination of organs and tissues with a thin pulsed beam of X-ray radiation in cross section, followed by computer processing of subtle differences in the absorption of X-rays and the secondary acquisition of a tomographic image of the object under study on a monitor or film. Modern X-ray computed tomographs consist of 4 main parts: 1- scanning system (X-ray tube and detectors); 2 - high-voltage generator - power source of 140 kV and current up to 200 mA; 3 - control panel (control keyboard, monitor); 4 - a computer system designed for preliminary processing of information received from detectors and obtaining an image with an assessment of the density of the object. CT has a number of advantages over conventional x-ray examination, primarily its greater sensitivity. It allows you to differentiate individual tissues from each other, differing in density within 1 - 2% and even 0.5%. With radiography, this figure is 10 - 20%. CT provides precise quantitative information about the size of the density of normal and pathological tissues. When using contrast agents, the method of so-called intravenous contrast enhancement increases the possibility of more accurately identifying pathological formations and conducting differential diagnostics.

In recent years, a new X-ray system for obtaining digital images has appeared. Each digital image consists of many individual points, which correspond to the numerical intensity of the glow. The degree of brightness of the dots is captured in a special device - an analog-to-digital converter (ADC), in which the electrical signal carrying information about the X-ray image is converted into a series of numbers, that is, digital coding of the signals occurs. To turn digital information into an image on a television screen or film, you need a digital-to-analog converter (DAC), where the digital image is transformed into an analog, visible image. Digital radiography will gradually replace conventional film radiography, since it is characterized by rapid image acquisition, does not require photochemical processing of the film, has greater resolution, allows mathematical image processing, archiving on magnetic storage media, and provides a significantly lower radiation dose to the patient (approximately 10 times), increases the throughput of the office.

The second method of radiation diagnostics is radionuclide diagnostics. Various radioactive isotopes and radionuclides are used as radiation sources.

Natural radioactivity was discovered in 1896 by A. Becquerel, and artificial radioactivity in 1934 by Irène and Joliot Curie. Most often in radionuclide diagnostics, radionuclides (RN) gamma emitters and radiopharmaceuticals (RP) with gamma emitters are used. A radionuclide is an isotope whose physical properties determine its suitability for radiodiagnostic studies. Radiopharmaceuticals are diagnostic and therapeutic agents based on radioactive nuclides - substances of inorganic or organic nature, the structure of which contains a radioactive element.

In dental practice and in radionuclide diagnostics in general, the following radionuclides are widely used: Tc 99 m, In-113 m, I-125, Xe-133, less often I-131, Hg-197. Based on their behavior in the body, radiopharmaceuticals used for radionuclide diagnostics are conventionally divided into 3 groups: organotropic, tropic to the pathological focus, and without pronounced selectivity or tropism. The tropism of radiopharmaceuticals can be directed, when the drug is included in the specific metabolism of the cells of a certain organ in which it accumulates, and indirect, when a temporary concentration of radiopharmaceuticals occurs in the organ along the way of its passage or excretion from the body. In addition, secondary selectivity is also distinguished, when the drug, not having the ability to accumulate, causes chemical transformations in the body that cause the emergence of new compounds that are already accumulated in certain organs or tissues. The most common launch vehicle currently is Tc 99 m, which is a daughter nuclide of radioactive molybdenum Mo 99. Tc 99 m is formed in a generator where Mo-99 decays by beta decay to form long-lived Tc-99 m. The latter, when decaying, emits gamma quanta with an energy of 140 keV (the most technically convenient energy). The half-life of Tc 99 m is 6 hours, which is sufficient for all radionuclide studies. It is excreted from the blood in the urine (30% within 2 hours) and accumulates in the bones. The preparation of radiopharmaceuticals based on the Tc 99 m label is carried out directly in the laboratory using a set of special reagents. The reagents, in accordance with the instructions supplied with the kits, are mixed in a certain way with the technetium eluate (solution) and a radiopharmaceutical is formed within a few minutes. Radiopharmaceutical solutions are sterile and pyrogen-free and can be administered intravenously. Numerous methods of radionuclide diagnostics are divided into 2 groups depending on whether the radiopharmaceutical is introduced into the patient’s body or is used to study isolated samples of biological media (blood plasma, urine and pieces of tissue). In the first case, the methods are combined into a group of in vivo studies, in the second case - in vitro. Both methods have fundamental differences in indications, execution techniques and results obtained. In clinical practice, complex studies are most often used. In vitro radionuclide studies are used to determine the concentration of various biologically active compounds in human blood serum, the number of which currently reaches more than 400 (hormones, drugs, enzymes, vitamins). They are used to diagnose and evaluate pathologies of the reproductive, endocrine, hematopoietic and immunological systems of the body. Most modern reagent kits are based on radioimmunoassay (RIA), which was first proposed by R. Yalow in 1959, for which the author was awarded the Nobel Prize in 1977.

Recently, along with RIA, a new technique of radioreceptor analysis (RRA) has been developed. PPA is also based on the principle of competitive equilibrium of a labeled ligand (labeled antigen) and the test substance in the serum, but not with antibodies, but with receptor bonds of the cell membrane. RRA differs from RIA in the shorter period of time for establishing the technique and even greater specificity.

The basic principles of in vivo radionuclide studies are:

1. Study of the distribution features of the administered radiopharmaceuticals in organs and tissues;

2. Determination of the dynamics of radiopharmaceutical absorption in the patient. Methods based on the first principle characterize the anatomical and topographical state of an organ or system and are called static radionuclide studies. Methods based on the second principle make it possible to assess the state of the functions of the organ or system being studied and are called dynamic radionuclide studies.

There are several methods for measuring the radioactivity of the body or its parts after the administration of a radiopharmaceutical.

Radiometry. This is a technique for measuring the intensity of the flow of ionizing radiation per unit of time, expressed in conventional units - pulses per second or minute (imp/sec). For measurements, radiometric equipment (radiometers, complexes) is used. This technique is used to study the accumulation of P 32 in skin tissues, to study the thyroid gland, to study the metabolism of proteins, iron, and vitamins in the body.

Radiography is a method of continuous or discrete recording of the processes of accumulation, redistribution and removal of radiopharmaceuticals from the body or individual organs. For these purposes, radiographs are used, in which a counting rate meter is connected to a recorder that draws a curve. The radiograph may contain one or more detectors, each of which carries out measurements independently of each other. If clinical radiometry is intended for single or several repeated measurements of the radioactivity of the body or its parts, then using radiography it is possible to trace the dynamics of accumulation and its elimination. A typical example of radiography is the study of the accumulation and removal of radiopharmaceuticals from the lungs (xenon), from the kidneys, from the liver. The radiographic function in modern devices is combined in a gamma camera with visualization of organs.

Radionuclide imaging. Methodology for creating a picture of the spatial distribution in organs of radiopharmaceuticals introduced into the body. Radionuclide imaging currently includes the following types:

• a) scanning,
• b) scintigraphy using a gamma camera,
• c) single-photon and two-photon positron emission tomography.

Scanning is a method of visualizing organs and tissues using a scintillation detector moving over the body. The device that conducts the study is called a scanner. The main disadvantage is the long duration of the study.

Scintigraphy is the process of obtaining images of organs and tissues by recording on a gamma camera the radiation emanating from radionuclides distributed in organs and tissues and in the body as a whole. Scintigraphy is currently the main method of radionuclide imaging in the clinic. It makes it possible to study the rapidly occurring processes of distribution of radioactive compounds introduced into the body.

Single photon emission tomography (SPET). SPET uses the same radiopharmaceuticals as scintigraphy. In this device, the detectors are located in a rotational tomography chamber, which rotates around the patient, making it possible, after computer processing, to obtain an image of the distribution of radionuclides in different layers of the body in space and time.

Two-photon emission tomography (TPET). For DFET, a positron-emitting radionuclide (C 11, N 13, O 15, F 18) is injected into the human body. Positrons emitted by these nuclides annihilate near the nuclei of atoms with electrons. During annihilation, the positron-electron pair disappears, forming two gamma rays with an energy of 511 keV. These two quanta, scattering in strictly opposite directions, are recorded by two also oppositely located detectors.

Computer signal processing allows you to obtain a three-dimensional and color image of the research object. The spatial resolution of DFET is worse than that of X-ray computed tomography and magnetic resonance imaging, but the sensitivity of the method is fantastic. DFET makes it possible to ascertain changes in the consumption of glucose, labeled with C 11, in the “eye center” of the brain, when opening the eyes; it is possible to identify changes in the thought process to determine the so-called. "soul", located, as some scientists believe, in the brain. The disadvantage of this method is that its use is only possible if there is a cyclotron, a radiochemical laboratory for obtaining short-lived nuclides, a positron tomograph and a computer for information processing, which is very expensive and cumbersome.

In the last decade, ultrasound diagnostics based on the use of ultrasound radiation has entered healthcare practice on a wide front.

Ultrasound radiation belongs to the invisible spectrum with a wavelength of 0.77-0.08 mm and an oscillation frequency of over 20 kHz. Sound vibrations with a frequency of more than 10 9 Hz are classified as hypersound. Ultrasound has certain properties:

• 1. In a homogeneous medium, ultrasound (US) is distributed rectilinearly at the same speed.
• 2. At the boundary of different media with unequal acoustic density, some of the rays are reflected, another part is refracted, continuing their linear propagation, and the third is attenuated.

Ultrasonic attenuation is determined by the so-called IMPEDANCE - ultrasonic attenuation. Its value depends on the density of the medium and the speed of propagation of the ultrasonic wave in it. The higher the gradient of the difference in the acoustic density of the boundary media, the larger part of the ultrasonic vibrations is reflected. For example, at the boundary of the transition of ultrasound from air to skin, almost 100% of vibrations (99.99%) are reflected. That is why during ultrasound examination (ultrasound) it is necessary to lubricate the surface of the patient’s skin with aqueous jelly, which acts as a transition medium that limits the reflection of radiation. Ultrasound is almost completely reflected from calcifications, giving a sharp weakening of echo signals in the form of an acoustic track (distal shadow). On the contrary, when examining cysts and cavities containing fluid, a track appears due to compensatory amplification of signals.

Three methods of ultrasound diagnostics are most widespread in clinical practice: one-dimensional examination (echography), two-dimensional examination (scanning, sonography) and Dopplerography.

1. One-dimensional echography is based on the reflection of U3 pulses, which are recorded on the monitor in the form of vertical bursts (curves) on a straight horizontal line (scan line). The one-dimensional method provides information about the distances between tissue layers along the path of the ultrasound pulse. One-dimensional echography is still used in the diagnosis of diseases of the brain (echoencephalography), the organ of vision, and the heart. In neurosurgery, echoencephalography is used to determine the size of the ventricles and the position of the midline diencephalic structures. In ophthalmological practice, this method is used to study the structures of the eyeball, vitreous opacities, retinal or choroidal detachment, and to clarify the location of a foreign body or tumor in the orbit. In a cardiology clinic, echography evaluates the structure of the heart in the form of a curve on a video monitor called an M-echogram (motion).

2. Two-dimensional ultrasound scanning (sonography). Allows you to obtain a two-dimensional image of organs (B-method, brightness - brightness). During sonography, the transducer moves in a direction perpendicular to the line of propagation of the ultrasound beam. The reflected impulses merge in the form of luminous points on the monitor. Since the sensor is in constant motion and the monitor screen has a long glow, the reflected impulses merge, forming a cross-sectional image of the organ being examined. Modern devices have up to 64 degrees of color gradation, called the “gray scale,” which provides differences in the structures of organs and tissues. The display produces an image in two qualities: positive (white background, black image) and negative (black background, white image).

Real-time visualization shows dynamic images of moving structures. It is provided by multidirectional sensors with up to 150 or more elements - linear scanning, or from one, but making rapid oscillatory movements - sectoral scanning. A real-time image of the organ being examined during ultrasound appears on the video monitor instantly from the moment of the examination. To study organs adjacent to open cavities (rectum, vagina, oral cavity, esophagus, stomach, colon), special intrarectal, intravaginal and other intracavitary sensors are used.

3. Doppler echolocation is a method of ultrasound diagnostic examination of moving objects (blood elements), based on the Doppler effect. The Doppler effect is associated with a change in the frequency of the ultrasonic wave perceived by the sensor, which occurs as a result of the movement of the object under study relative to the sensor: the frequency of the echo signal reflected from the moving object differs from the frequency of the emitted signal. There are two modifications of Dopplerography:

• a) - continuous, which is most effective when measuring high blood flow velocities in places of vascular constriction, however, continuous Dopplerography has a significant drawback - it gives the total speed of the object, and not just the blood flow;
• b) - pulse Dopplerography is free of these disadvantages and allows you to measure low velocities at great depths or high velocities at shallow depths in several small control objects.

Dopplerography is used clinically to study the shape of the contours and lumens of blood vessels (narrowings, thrombosis, individual sclerotic plaques). In recent years, the combination of sonography and Dopplerography (so-called duplex sonography) has become important in the ultrasound diagnostic clinic, which allows one to identify images of blood vessels (anatomical information) and obtain a record of the blood flow curve in them (physiological information), also in modern Ultrasound devices have a system that allows you to color multidirectional blood flows in different colors (blue and red), the so-called color Doppler mapping. Duplex sonography and color mapping make it possible to monitor the blood supply to the placenta, heart contractions in the fetus, the direction of blood flow in the chambers of the heart, determine the reverse flow of blood in the portal vein system, calculate the degree of vascular stenosis, etc.

In recent years, some biological effects in personnel during ultrasound examinations have become known. The effect of ultrasound through the air primarily affects the critical volume, which is the blood sugar level, electrolyte shifts are noted, fatigue increases, headaches, nausea, tinnitus, and irritability occur. However, in most cases, these signs are nonspecific and have a pronounced subjective coloring. This issue requires further study.

Medical thermography is a method of recording the natural thermal radiation of the human body in the form of invisible infrared radiation. Infrared radiation (IR) is produced by all bodies with a temperature above minus 237 0 C. The wavelength of IIR is from 0.76 to 1 mm. The radiation energy is less than that of visible light quanta. IR is absorbed and weakly scattered, and has both wave and quantum properties. Features of the method:

• 1. Absolutely harmless.
• 2. High research speed (1 - 4 min.).
• 3. Quite accurate - it picks up fluctuations of 0.1 0 C.
• 4. Has the ability to simultaneously assess the functional state of several organs and systems.

Thermographic research methods:

• 1. Contact thermography is based on the use of thermal indicator films on liquid crystals in a color image. By coloring the image using a calorimetric ruler, the temperature of the surface tissues is judged.
• 2. Remote infrared thermography is the most common method of thermography. It provides an image of the thermal relief of the body surface and measurement of temperature in any part of the human body. A remote thermal imager makes it possible to display a person’s thermal field on the device’s screen in the form of a black-and-white or color image. These images can be recorded on photochemical paper and a thermogram can be obtained. Using the so-called active, stress tests: cold, hyperthermic, hyperglycemic, it is possible to identify initial, even hidden violations of thermoregulation of the surface of the human body.

Currently, thermography is used to detect circulatory disorders, inflammatory, tumor and some occupational diseases, especially during dispensary observation. It is believed that this method, while having sufficient sensitivity, does not have high specificity, which makes it difficult to widely use in diagnosing various diseases.

The latest achievements of science and technology make it possible to measure the temperature of internal organs by their own radiation of radio waves in the microwave range. These measurements are made using a microwave radiometer. This method has a more promising future than infrared thermography.

A huge event of the last decade has been the introduction into clinical practice of a truly revolutionary diagnostic method, nuclear magnetic resonance imaging, currently called magnetic resonance imaging (the word “nuclear” has been removed so as not to cause radiophobia among the population). The magnetic resonance imaging (MRI) method is based on capturing electromagnetic vibrations from certain atoms. The fact is that atomic nuclei containing an odd number of protons and neutrons have their own nuclear magnetic spin, i.e. angular momentum of rotation of the nucleus around its own axis. These atoms include hydrogen, a component of water, which reaches up to 90% in the human body. A similar effect is produced by other atoms containing an odd number of protons and neutrons (carbon, nitrogen, sodium, potassium and others). Therefore, each atom is like a magnet and under normal conditions the axes of angular momentum are located randomly. In a magnetic field of the diagnostic range with a power of the order of 0.35-1.5 T (the unit of measurement of the magnetic field is named after Tesla, a Serbian, Yugoslav scientist with 1000 inventions), atoms are oriented parallel or antiparallel in the direction of the magnetic field. If a radio frequency field (of the order of 6.6-15 MHz) is applied in this state, nuclear magnetic resonance occurs (resonance, as is known, occurs when the excitation frequency coincides with the natural frequency of the system). This radio frequency signal is picked up by detectors and an image is created through a computer system based on proton density (the more protons in the medium, the more intense the signal). The brightest signal is produced by adipose tissue (high proton density). On the contrary, bone tissue, due to a small amount of water (protons), gives the smallest signal. Each tissue has its own signal.

Magnetic resonance imaging has a number of advantages over other diagnostic imaging methods:

• 1. No radiation exposure,
• 2. There is no need to use contrast agents in most cases of routine diagnostics, since MRI allows you to see With Vessels, especially large and medium ones without contrasting.
• 3. The ability to obtain images in any plane, including three orthoganal anatomical projections, in contrast to X-ray computed tomography, where the study is carried out in an axial projection, and in contrast to ultrasound, where the image is limited (longitudinal, transverse, sectoral).
• 4. High resolution of identifying soft tissue structures.
• 5. There is no need for special preparation of the patient for the study.

In recent years, new methods of radiation diagnostics have appeared: obtaining a three-dimensional image using spiral computed x-ray tomography, a method has emerged using the principle of virtual reality with a three-dimensional image, monoclonal radionuclide diagnostics and some other methods that are at the experimental stage.

Thus, this lecture provides a general description of the methods and techniques of radiation diagnostics; a more detailed description of them will be given in private sections.

PREFACE

Medical radiology (radiation diagnostics) is a little over 100 years old. During this historically short period of time, she wrote many bright pages in the chronicle of the development of science - from the discovery of V.K. Roentgen (1895) to the rapid computer processing of medical radiation images.

At the origins of domestic X-ray radiology were M.K. Nemenov, E.S. London, D.G. Rokhlin, D.S. Lindenbraten - outstanding organizers of science and practical healthcare. Such outstanding personalities as S.A. Reinberg, G.A. Zedgenizde, V.Ya. Dyachenko, Yu.N. Sokolov, L.D. Lindenbraten and others made a great contribution to the development of radiation diagnostics.

The main goal of the discipline is to study theoretical and practical issues of general radiation diagnostics (x-ray, radionuclide,

ultrasound, computed tomography, magnetic resonance imaging, etc.) necessary in the future for students to successfully master clinical disciplines.

Today, radiation diagnostics, taking into account clinical and laboratory data, allows 80-85% to recognize the disease.

This guide to radiation diagnostics is compiled in accordance with the State Educational Standard (2000) and the Curriculum approved by VUNMC (1997).

Today, the most common method of radiological diagnostics is traditional X-ray examination. Therefore, when studying radiology, the main attention is paid to methods for studying human organs and systems (fluoroscopy, radiography, ERG, fluorography, etc.), methods for analyzing radiographs and general x-ray semiotics of the most common diseases.

Currently, digital radiography with high image quality is successfully developing. It is distinguished by its speed, the ability to transmit images over a distance, and the convenience of storing information on magnetic media (disks, tapes). An example is X-ray computed tomography (XCT).

The ultrasound method of examination (ultrasound) deserves attention. Due to its simplicity, harmlessness and effectiveness, the method is becoming one of the most common.

CURRENT STATE AND PROSPECTS FOR THE DEVELOPMENT OF RADIOLOGICAL DIAGNOSTICS

Radiation diagnostics (diagnostic radiology) is an independent branch of medicine that combines various methods of obtaining images for diagnostic purposes based on the use of various types of radiation.

Currently, the activities of radiation diagnostics are regulated by the following regulatory documents:

1. Order of the Ministry of Health of the Russian Federation No. 132 dated August 2, 1991 “On improving the radiology diagnostic service.”

2. Order of the Ministry of Health of the Russian Federation No. 253 dated June 18, 1996 “On further improvement of work to reduce radiation doses during medical procedures”

3. Order No. 360 of September 14, 2001. “On approval of the list of radiation research methods.”

Radiation diagnostics includes:

1. Methods based on the use of X-rays.

1). Fluorography

2). Traditional X-ray examination

4). Angiography

2. Methods based on the use of ultrasound radiation 1).Ultrasound

2). Echocardiography

3). Dopplerography

3. Methods based on nuclear magnetic resonance. 1).MRI

2). MP spectroscopy

4. Methods based on the use of radiopharmaceuticals (radiopharmacological drugs):

1). Radionuclide diagnostics

2). Positron emission tomography - PET

3). Radioimmune studies

5.Methods based on infrared radiation (thermophafia)

6.Interventional radiology

Common to all research methods is the use of various radiations (X-rays, gamma rays, ultrasound, radio waves).

The main components of radiation diagnostics are: 1) radiation source, 2) sensing device.

The diagnostic image is usually a combination of different shades of gray color, proportional to the intensity of the radiation hitting the receiving device.

A picture of the internal structure of the study of an object can be:

1) analog (on film or screen)

2) digital (radiation intensity is expressed in the form of numerical values).

All these methods are combined into a common specialty - radiation diagnostics (medical radiology, diagnostic radiology), and the doctors are radiologists (abroad), but here we still have an unofficial “radiology diagnostician”

In the Russian Federation, the term radiology diagnostics is official only to designate a medical specialty (14.00.19); departments also have a similar name. In practical healthcare, the name is conditional and combines 3 independent specialties: radiology, ultrasound diagnostics and radiology (radionuclide diagnostics and radiation therapy).

Medical thermography is a method of recording natural thermal (infrared) radiation. The main factors determining body temperature are: the intensity of blood circulation and the intensity of metabolic processes. Each region has its own “thermal relief”. Using special equipment (thermal imagers), infrared radiation is captured and converted into a visible image.

Patient preparation: discontinuation of medications that affect blood circulation and the level of metabolic processes, prohibition of smoking 4 hours before the examination. There should be no ointments, creams, etc. on the skin.

Hyperthermia is characteristic of inflammatory processes, malignant tumors, thrombophlebitis; hypothermia is observed with vasospasms, circulatory disorders in occupational diseases (vibration disease, cerebrovascular accident, etc.).

The method is simple and harmless. However, the diagnostic capabilities of the method are limited.

One of the widely used modern methods is ultrasound (ultrasonic dowsing). The method has become widespread due to its simplicity, accessibility, and high information content. In this case, the frequency of sound vibrations is used from 1 to 20 megahertz (a person hears sound within frequencies from 20 to 20,000 hertz). A beam of ultrasonic vibrations is directed to the area under study, which is partially or completely reflected from all surfaces and inclusions that differ in sound conductivity. The reflected waves are captured by a sensor, processed by an electronic device and converted into a one-dimensional (echography) or two-dimensional (sonography) image.

Based on the difference in the sound density of the picture, one or another diagnostic decision is made. From the scanograms one can judge the topography, shape, size of the organ being studied, as well as pathological changes in it. Being harmless to the body and staff, the method has found wide application in obstetric and gynecological practice, in the study of the liver and biliary tract, retroperitoneal organs and other organs and systems.

Radionuclide methods for imaging various human organs and tissues are rapidly developing. The essence of the method is that radionuclides or radioactive compounds labeled with them are introduced into the body, which selectively accumulate in the corresponding organs. In this case, radionuclides emit gamma quanta, which are detected by sensors and then recorded by special devices (scanners, gamma camera, etc.), which makes it possible to judge the position, shape, size of the organ, distribution of the drug, the speed of its elimination, etc.

Within the framework of radiation diagnostics, a new promising direction is emerging - radiological biochemistry (radioimmune method). At the same time, hormones, enzymes, tumor markers, drugs, etc. are studied. Today, more than 400 biologically active substances are determined in vitro; Methods of activation analysis are being successfully developed - determining the concentration of stable nuclides in biological samples or in the body as a whole (irradiated with fast neutrons).

The leading role in obtaining images of human organs and systems belongs to X-ray examination.

With the discovery of X-rays (1895), the age-old dream of a doctor came true - to look inside a living organism, study its structure, work, and recognize a disease.

Currently, there are a large number of X-ray examination methods (non-contrast and using artificial contrast), which make it possible to examine almost all human organs and systems.

Recently, digital imaging technologies (low-dose digital radiography), flat panels - detectors for REOP, X-ray image detectors based on amorphous silicon, etc. - have been increasingly introduced into practice.

The advantages of digital technologies in radiology: reduction of the radiation dose by 50-100 times, high resolution (objects 0.3 mm in size are visualized), film technology is eliminated, office throughput increases, an electronic archive is formed with quick access, and the ability to transmit images over a distance.

Interventional radiology is closely related to radiology - a combination of diagnostic and therapeutic measures in one procedure.

Main directions: 1) X-ray vascular interventions (expansion of narrowed arteries, blockage of blood vessels with hemangiomas, vascular prosthetics, stopping bleeding, removal of foreign bodies, supply of drugs to the tumor), 2) extravasal interventions (catheterization of the bronchial tree, puncture of the lung, mediastinum, decompression with obstructive jaundice, administration of drugs that dissolve stones, etc.).

CT scan. Until recently, it seemed that the methodological arsenal of radiology was exhausted. However, computed tomography (CT) was born, revolutionizing X-ray diagnostics. Almost 80 years after the Nobel Prize received by Roentgen (1901), in 1979 the same prize was awarded to Hounsfield and Cormack on the same part of the scientific front - for the creation of a computed tomograph. Nobel Prize for creating the device! The phenomenon is quite rare in science. And the whole point is that the capabilities of the method are quite comparable to the revolutionary discovery of Roentgen.

The disadvantage of the x-ray method is the flat image and the overall effect. With CT, the image of an object is mathematically reconstructed from a countless set of its projections. Such an object is a thin slice. At the same time, it is illuminated from all sides and its image is recorded by a huge number of highly sensitive sensors (several hundred). The received information is processed on a computer. CT detectors are very sensitive. They detect differences in the density of structures of less than one percent (with conventional radiography - 15-20%). From here, you can get images of various structures of the brain, liver, pancreas and a number of other organs.

Advantages of CT: 1) high resolution, 2) examination of the thinnest section - 3-5 mm, 3) the ability to quantify density from -1000 to + 1000 Hounsfield units.

Currently, spiral computed tomographs have appeared that provide examination of the entire body and obtain tomograms in normal operating mode in one second and image reconstruction time from 3 to 4 seconds. For the creation of these devices, scientists were awarded the Nobel Prize. Mobile CT scanners have also appeared.

Magnetic resonance imaging is based on nuclear magnetic resonance. Unlike an X-ray machine, a magnetic tomograph does not “examine” the body with rays, but forces the organs themselves to send radio signals, which the computer processes to form an image.

Work principles. The object is placed in a constant magnetic field, which is created by a unique electromagnet in the form of 4 huge rings connected together. On the couch, the patient is moved into this tunnel. A powerful constant electromagnetic field is turned on. In this case, the protons of hydrogen atoms contained in the tissues are oriented strictly along the lines of force (under normal conditions they are randomly oriented in space). Then the high-frequency electromagnetic field is turned on. Now the nuclei, returning to their original state (position), emit tiny radio signals. This is the NMR effect. The computer registers these signals and the distribution of protons and forms an image on a television screen.

Radio signals are not the same and depend on the location of the atom and its environment. Atoms of painful areas emit a radio signal that differs from the radiation of neighboring healthy tissues. The resolution of the devices is extremely high. For example, individual structures of the brain are clearly visible (stem, hemisphere, gray, white matter, ventricular system, etc.). Advantages of MRI over CT:

1) MP tomography is not associated with the risk of tissue damage, unlike x-ray examination.

2) Scanning with radio waves allows you to change the location of the section being studied in the body”; without changing the patient's position.

3) The image is not only transverse, but also in any other sections.

4) Resolution is higher than with CT.

Obstacles to MRI are metal bodies (clips after surgery, cardiac pacemakers, electrical neurostimulators)

Current trends in the development of radiation diagnostics

1. Improving methods based on computer technology

2. Expanding the scope of application of new high-tech methods - ultrasound, MRI, X-ray CT, PET.

4. Replacement of labor-intensive and invasive methods with less dangerous ones.

5. Maximum reduction of radiation exposure to patients and staff.

Comprehensive development of interventional radiology, integration with other medical specialties.

The first direction is a breakthrough in the field of computer technology, which made it possible to create a wide range of devices for digital digital radiography, ultrasound, MRI to the use of three-dimensional images.

One laboratory per 200-300 thousand population. It should preferably be placed in therapeutic clinics.

1. It is necessary to place the laboratory in a separate building, built according to a standard design with a security sanitary zone around it. It is forbidden to build children's institutions and catering units on the territory of the latter.

2. The radionuclide laboratory must have a certain set of premises (radiopharmaceutical storage, packaging, generator, washing, treatment room, sanitary inspection room).

3. Special ventilation is provided (five air changes when using radioactive gases), sewerage with a number of settling tanks in which waste of at least ten half-lives is kept.

4. Daily wet cleaning of the premises must be carried out.

In the coming years, and sometimes even today, the main place of work of a doctor will be a personal computer, on the screen of which information with electronic medical history data will be displayed.

The second direction is associated with the widespread use of CT, MRI, PET, and the development of ever new areas of their use. Not from simple to complex, but choosing the most effective methods. For example, detection of tumors, metastases of the brain and spinal cord - MRI, metastases - PET; renal colic - spiral CT.

The third direction is the widespread elimination of invasive methods and methods associated with high radiation exposure. In this regard, today myelography, pneumomediastinography, intravenous cholegraphy, etc. have practically disappeared. Indications for angiography are being reduced.

The fourth direction is the maximum reduction of doses of ionizing radiation due to: I) replacing X-ray emitters MRI, ultrasound, for example, when examining the brain and spinal cord, biliary tract, etc. But this must be done deliberately so that a situation does not happen similar to an X-ray examination of the gastrointestinal tract, where everything shifted to FGS, although for endophytic cancers more information is obtained from X-ray examination. Today, ultrasound cannot replace mammography. 2) maximum reduction of doses during the X-ray examinations themselves by eliminating duplication of images, improving technology, film, etc.

The fifth direction is the rapid development of interventional radiology and the widespread involvement of radiation diagnosticians in this work (angiography, puncture of abscesses, tumors, etc.).

Features of individual diagnostic methods at the present stage

In traditional radiology, the layout of X-ray machines has fundamentally changed - installation on three workstations (images, transillumination and tomography) is replaced by a remote-controlled one workstation. The number of special devices has increased (mammographs, angiography, dentistry, ward, etc.). Devices for digital radiography, URI, subtraction digital angiography, and photostimulating cassettes have become widespread. Digital and computer radiology has emerged and is developing, which leads to a reduction in examination time, the elimination of the darkroom process, the creation of compact digital archives, the development of teleradiology, and the creation of intra- and interhospital radiological networks.

Ultrasound technologies have been enriched with new programs for digital processing of echo signals, and Dopplerography for assessing blood flow is intensively developing. Ultrasound has become the main method in the study of the abdomen, heart, pelvis, and soft tissues of the extremities; the importance of the method in the study of the thyroid gland, mammary glands, and intracavitary studies is increasing.

In the field of angiography, interventional technologies are intensively developing (balloon dilatation, installation of stents, angioplasty, etc.)

In RCT, spiral scanning, multilayer CT, and CT angiography become dominant.

MRI has been enriched with open-type installations with a field strength of 0.3 - 0.5 T and with high intensity (1.7-3 OT), functional methods for studying the brain.

A number of new radiopharmaceuticals have appeared in radionuclide diagnostics, and PET (oncology and cardiology) has established itself in the clinic.

Telemedicine is emerging. Its task is electronic archiving and transmission of patient data over a distance.

The structure of radiation research methods is changing. Traditional X-ray examinations, testing and diagnostic fluorography, ultrasound are methods of primary diagnosis and are mainly focused on studying the organs of the thoracic and abdominal cavity, and the osteoarticular system. Specifying methods include MRI, CT, radionuclide studies, especially when examining bones, dentofacial area, head and spinal cord.

Currently, over 400 compounds of various chemical natures have been developed. The method is an order of magnitude more sensitive than laboratory biochemical studies. Today, radioimmunoassay is widely used in endocrinology (diabetes mellitus diagnosis), oncology (search for cancer markers), in cardiology (myocardial infarction diagnosis), in pediatrics (for child development disorders), in obstetrics and gynecology (infertility, fetal development disorders), in allergology, toxicology, etc.

In industrialized countries, the main emphasis is now on organizing positron emission tomography (PET) centers in large cities, which, in addition to a positron emission tomograph, also includes a small-sized cyclotron for the on-site production of positron-emitting ultrashort-lived radionuclides. Where there are no small-sized cyclotrons, the isotope (F-18 with a half-life of about 2 hours) is obtained from their regional radionuclide production centers or generators (Rb-82, Ga-68, Cu-62) are used.

Currently, radionuclide research methods are also used for preventive purposes to identify hidden diseases. Thus, any headache requires a brain study with pertechnetate-Tc-99sh. This type of screening allows us to exclude tumors and areas of hemorrhage. A reduced kidney detected in childhood by scintigraphy should be removed to prevent malignant hypertension. A drop of blood taken from the child’s heel allows you to determine the amount of thyroid hormones.

Methods of radionuclide research are divided into: a) research of a living person; b) examination of blood, secretions, excreta and other biological samples.

In vivo methods include:

1. Radiometry (of the whole body or part of it) - determination of the activity of a part of the body or organ. Activity is recorded as numbers. An example is the study of the thyroid gland and its activity.

2. Radiography (gammachronography) - on a radiograph or gamma camera, the dynamics of radioactivity is determined in the form of curves (hepatoradiography, radiorenography).

3. Gammatopography (on a scanner or gamma camera) - the distribution of activity in an organ, which allows one to judge the position, shape, size, and uniformity of drug accumulation.

4. Radioimmunoassay (radiocompetitive) - hormones, enzymes, drugs, etc. are determined in a test tube. In this case, the radiopharmaceutical is introduced into a test tube, for example, with the patient’s blood plasma. The method is based on competition between a substance labeled with a radionuclide and its analog in a test tube for complexing (combining) with a specific antibody. An antigen is a biochemical substance that needs to be determined (hormone, enzyme, drug). For analysis you must have: 1) the test substance (hormone, enzyme); 2) its labeled analogue: the label is usually 1-125 with a half-life of 60 days or tritium with a half-life of 12 years; 3) a specific perceptive system, which is the subject of “competition” between the desired substance and its labeled analogue (antibody); 4) a separation system that separates bound radioactive substances from unbound ones (activated carbon, ion exchange resins, etc.).

RADIATION STUDY OF THE LUNG

The lungs are one of the most common objects of radiation research. The important role of x-ray examination in the study of the morphology of the respiratory organs and the recognition of various diseases is evidenced by the fact that the accepted classifications of many pathological processes are based on x-ray data (pneumonia, tuberculosis, lung cancer, sarcoidosis, etc.). Often hidden diseases such as tuberculosis, cancer, etc. are detected during screening fluorographic examinations. With the advent of computed tomography, the importance of X-ray examination of the lungs has increased. An important place in the study of pulmonary blood flow belongs to radionuclide research. Indications for radiation examination of the lungs are very wide (cough, sputum production, shortness of breath, fever, etc.).

Radiation examination allows you to diagnose the disease, clarify the localization and extent of the process, monitor the dynamics, monitor recovery, and detect complications.

The leading role in the study of the lungs belongs to X-ray examination. Among the research methods, fluoroscopy and radiography should be noted, which allow assessing both morphological and functional changes. The methods are simple and not burdensome for the patient, highly informative, and publicly available. Typically, survey images are taken in frontal and lateral projections, targeted images, superexposed (super-rigid, sometimes replacing tomography). To identify fluid accumulation in the pleural cavity, photographs are taken in a later position on the affected side. In order to clarify the details (the nature of the contours, the homogeneity of the shadow, the condition of the surrounding tissues, etc.), tomography is performed. For mass examination of the chest organs, fluorography is used. Contrast methods include bronchography (to detect bronchiectasis), angiopulmonography (to determine the extent of the process, for example in lung cancer, to detect thromboembolism of the branches of the pulmonary artery).

X-ray anatomy. Analysis of radiological data of the chest organs is carried out in a certain sequence. Evaluated:

1) image quality (correct positioning of the patient, degree of film exposure, capture volume, etc.),

2) the condition of the chest as a whole (shape, size, symmetry of the pulmonary fields, position of the mediastinal organs),

3) the condition of the skeleton that forms the chest (shoulder girdle, ribs, spine, collarbones),

4) soft tissues (skin strip over the collarbones, shadow and sternocleidopapillary muscles, mammary glands),

5) state of the diaphragm (position, shape, contours, sinuses),

6) condition of the roots of the lungs (position, shape, width, condition of the outer skin, structure),

7) state of the pulmonary fields (size, symmetry, pulmonary pattern, transparency),

8) condition of the mediastinal organs. It is necessary to study the bronchopulmonary segments (name, location).

X-ray semiotics of lung diseases is extremely diverse. However, this diversity can be reduced to several groups of characteristics.

1. Morphological characteristics:

1) dimming

2) enlightenment

3) a combination of darkening and brightening

4) changes in pulmonary pattern

5) root pathology

2. Functional characteristics:

1) change in the transparency of the lung tissue in the inhalation and exhalation phases

2) mobility of the diaphragm during breathing

3) paradoxical movements of the diaphragm

4) movement of the median shadow in the inhalation and exhalation phases. Having detected pathological changes, it is necessary to decide what disease they are caused by. It is usually impossible to do this “at first glance” if there are no pathognomonic symptoms (needle, badge, etc.). The task is made easier if you isolate the radiological syndrome. The following syndromes are distinguished:

1. Total or subtotal blackout syndrome:

1) intrapulmonary opacities (pneumonia, atelectasis, cirrhosis, hiatal hernia),

2) extrapulmonary opacities (exudative pleurisy, moorings). The distinction is based on two features: the structure of the darkening and the position of the mediastinal organs.

For example, the shadow is homogeneous, the mediastinum is shifted towards the lesion - atelectasis; the shadow is homogeneous, the heart is shifted to the opposite side - exudative pleurisy.

2. Restricted dimming syndrome:

1) intrapulmonary (lobe, segment, subsegment),

2) extrapulmonary (pleural effusion, changes in the ribs and mediastinal organs, etc.).

Limited darkening is the most difficult way of diagnostic decoding (“oh, not lungs - these lungs!”). They occur in pneumonia, tuberculosis, cancer, atelectasis, thromboembolism of the branches of the pulmonary artery, etc. Consequently, the detected shadow should be assessed in terms of position, shape, size, nature of the contours, intensity and homogeneity, etc.

Round (spherical) darkening syndrome - in the form of one or several foci that have a more or less rounded shape measuring more than one cm. They can be homogeneous or heterogeneous (due to decay and calcification). A rounded shadow must be determined in two projections.

According to localization, rounded shadows can be:

1) intrapulmonary (inflammatory infiltrate, tumor, cysts, etc.) and

2) extrapulmonary, originating from the diaphragm, chest wall, mediastinum.

Today there are about 200 diseases that cause a round shadow in the lungs. Most of them are rare.

Therefore, most often it is necessary to carry out differential diagnosis with the following diseases:

1) peripheral lung cancer,

2) tuberculoma,

3) benign tumor,

5) lung abscess and foci of chronic pneumonia,

6) solid metastasis. These diseases account for up to 95% of rounded shadows.

When analyzing a round shadow, one should take into account the localization, structure, nature of the contours, the state of the lung tissue around, the presence or absence of a “path” to the root, etc.

4.0 focal (focal-like) darkenings are round or irregularly shaped formations with a diameter of 3 mm to 1.5 cm. Their nature is varied (inflammatory, tumor, cicatricial changes, areas of hemorrhage, atelectasis, etc.). They can be single, multiple or disseminated and vary in size, location, intensity, nature of contours, and changes in the pulmonary pattern. So, when localization of foci in the area of ​​the apex of the lung, subclavian space, one should think about tuberculosis. Uneven contours usually characterize inflammatory processes, peripheral cancer, foci of chronic pneumonia, etc. The intensity of the foci is usually compared with the pulmonary pattern, rib, and median shadow. In differential diagnosis, dynamics (increase or decrease in the number of lesions) is also taken into account.

Focal shadows are most often found in tuberculosis, sarcoidosis, pneumonia, metastases of malignant tumors, pneumoconiosis, pneumosclerosis, etc.

5. Dissemination syndrome - spread of multiple focal shadows in the lungs. Today there are over 150 diseases that can cause this syndrome. The main delimiting criteria are:

1) sizes of lesions - miliary (1-2 mm), small (3-4 mm), medium (5-8 mm) and large (9-12 mm),

2) clinical manifestations,

3) preferential localization,

4) dynamics.

Miliary dissemination is characteristic of acute disseminated (miliary) tuberculosis, nodular pneumoconiosis, sarcoidosis, carcinomatosis, hemosiderosis, histiocytosis, etc.

When assessing the X-ray picture, one should take into account the localization, uniformity of dissemination, the state of the pulmonary pattern, etc.

Dissemination with lesions larger than 5 mm reduces the diagnostic task to distinguishing between focal pneumonia, tumor dissemination, and pneumosclerosis.

Diagnostic errors in dissemination syndrome are quite frequent and amount to 70-80%, and therefore adequate therapy is delayed. Currently, disseminated processes are divided into: 1) infectious (tuberculosis, mycoses, parasitic diseases, HIV infection, respiratory distress syndrome), 2) non-infectious (pneumoconiosis, allergic vasculitis, drug changes, radiation consequences, post-transplant changes, etc.).

About half of all disseminated lung diseases are related to processes of unknown etiology. For example, idiopathic fibrosing alveolitis, sarcoidosis, histiocytosis, idiopathic hemosiderosis, vasculitis. In some systemic diseases, dissemination syndrome is also observed (rheumatoid diseases, liver cirrhosis, hemolytic anemia, heart disease, kidney disease, etc.).

Recently, X-ray computed tomography (XCT) has provided great assistance in the differential diagnosis of disseminated processes in the lungs.

6. Clearance syndrome. Clearances in the lungs are divided into limited (cavity formations - ring-shaped shadows) and diffuse. Diffuse, in turn, are divided into structureless (pneumothorax) and structural (pulmonary emphysema).

Ring shadow (clearance) syndrome manifests itself in the form of a closed ring (in two projections). If a ring-shaped clearing is detected, it is necessary to establish the location, wall thickness, and condition of the lung tissue around. Hence, they distinguish:

1) thin-walled cavities, which include bronchial cysts, racemose bronchiectasis, post-pneumonic (false) cysts, sanitized tuberculous cavities, emphysematous bullae, cavities with staphylococcal pneumonia;

2) unevenly thick cavity walls (disintegrating peripheral cancer);

3) uniformly thick walls of the cavity (tuberculous cavities, lung abscess).

7. Pathology of the pulmonary pattern. The pulmonary pattern is formed by the branches of the pulmonary artery and appears as linear shadows located radially and not reaching the costal margin by 1-2 cm. The pathologically altered pulmonary pattern can be enhanced or depleted.

1) Strengthening of the pulmonary pattern manifests itself in the form of coarse additional stringy formations, often randomly located. Often it becomes loopy, cellular, and chaotic.

Strengthening and enrichment of the pulmonary pattern (per unit area of ​​lung tissue there is an increase in the number of elements of the pulmonary pattern) is observed with arterial congestion of the lungs, congestion in the lungs, and pneumosclerosis. Strengthening and deformation of the pulmonary pattern is possible:

a) small-cell type and b) large-cell type (pneumosclerosis, bronchiectasis, cystic lung).

Strengthening of the pulmonary pattern can be limited (pneumofibrosis) and diffuse. The latter occurs in fibrosing alveolitis, sarcoidosis, tuberculosis, pneumoconiosis, histiocytosis X, tumors (cancerous lymphangitis), vasculitis, radiation injuries, etc.

Depletion of the pulmonary pattern. At the same time, there are fewer elements of the pulmonary pattern per unit area of ​​the lung. Depletion of the pulmonary pattern is observed with compensatory emphysema, underdevelopment of the arterial network, valve blockage of the bronchus, progressive pulmonary dystrophy (disappearing lung), etc.

The disappearance of the pulmonary pattern is observed with atelectasis and pneumothorax.

8. Pathology of roots. There are normal roots, infiltrated roots, stagnant roots, roots with enlarged lymph nodes and fibrosis-unchanged roots.

A normal root is located from 2 to 4 ribs, has a clear outer contour, the structure is heterogeneous, the width does not exceed 1.5 cm.

The differential diagnosis of pathologically altered roots takes into account the following points:

1) one or two sided lesions,

2) changes in the lungs,

3) clinical picture (age, ESR, changes in blood, etc.).

The infiltrated root appears expanded, structureless with an unclear outer contour. Occurs in inflammatory lung diseases and tumors.

Stagnant roots look exactly the same. However, the process is two-sided and there are usually changes in the heart.

Roots with enlarged lymph nodes are structureless, expanded, with a clear outer boundary. Sometimes there is polycyclicity, a symptom of “backstage”. Occurs in systemic blood diseases, metastases of malignant tumors, sarcoidosis, tuberculosis, etc.

The fibrotic root is structural, usually displaced, often has calcified lymph nodes and, as a rule, there are fibrotic changes in the lungs.

9. The combination of darkening and clearing is a syndrome that is observed in the presence of a decay cavity of a purulent, caseous or tumor nature. Most often it occurs in the cavitary form of lung cancer, tuberculosis cavity, disintegrating tuberculosis infiltrate, lung abscess, suppurating cysts, bronchiectasis, etc.

10. Pathology of the bronchi:

1) violation of bronchial obstruction due to tumors and foreign bodies. There are three degrees of bronchial obstruction (hypoventilation, ventilatory obstruction, atelectasis),

2) bronchiectasis (cylindrical, saccular and mixed bronchiectasis),

3) deformation of the bronchi (with pneumosclerosis, tuberculosis and other diseases).

RADIATION STUDY OF THE HEART AND GREAT VESSELS

Radiation diagnostics of diseases of the heart and large vessels has come a long way in its development, full of triumph and drama.

The great diagnostic role of X-ray cardiology has never been in doubt. But this was her youth, a time of loneliness. In the last 15-20 years, there has been a technological revolution in diagnostic radiology. Thus, in the 70s, ultrasound devices were created that made it possible to look inside the cavities of the heart and study the condition of the drip apparatus. Later, dynamic scintigraphy made it possible to judge the contractility of individual segments of the heart and the nature of blood flow. In the 80s, computerized methods of obtaining images entered the practice of cardiology: digital coronary and ventriculography, CT, MRI, cardiac catheterization.

Recently, the opinion has become widespread that traditional X-ray examination of the heart has become obsolete as a technique for examining cardiac patients, since the main methods for examining the heart are ECG, ultrasound, and MRI. However, in assessing pulmonary hemodynamics, which reflects the functional state of the myocardium, X-ray examination retains its advantages. It not only allows you to identify changes in the vessels of the pulmonary circulation, but also provides an idea of ​​the chambers of the heart that led to these changes.

Thus, radiation examination of the heart and large vessels includes:

non-invasive methods (fluoroscopy and radiography, ultrasound, CT, MRI)

invasive methods (angiocardiography, ventriculography, coronary angiography, aortography, etc.)

Radionuclide methods make it possible to judge hemodynamics. Consequently, today radiology diagnostics in cardiology is experiencing its maturity.

X-ray examination of the heart and great vessels.

Method value. X-ray examination is part of the general clinical examination of the patient. The goal is to establish the diagnosis and nature of hemodynamic disorders (the choice of treatment method - conservative, surgical) depends on this. In connection with the use of URI in combination with cardiac catheterization and angiography, broad prospects have opened up in the study of circulatory disorders.

Research methods

1) Fluoroscopy is the technique with which the study begins. It allows you to get an idea of ​​the morphology and give a functional description of the shadow of the heart as a whole and its individual cavities, as well as large vessels.

2) Radiography objectifies the morphological data obtained during fluoroscopy. Its standard projections:

a) front straight

b) right anterior oblique (45°)

c) left anterior oblique (45°)

d) left side

Signs of oblique projections:

1) Right oblique - a triangular shape of the heart, a gas bubble of the stomach in front, along the posterior contour on top is the ascending aorta, the left atrium, below - the right atrium; along the anterior contour, the aorta is determined from above, then there is the cone of the pulmonary artery and, below, the arch of the left ventricle.

2) Left oblique - oval in shape, the gastric bladder is behind, between the spine and the heart, the bifurcation of the trachea is clearly visible and all parts of the thoracic aorta are identified. All chambers of the heart open onto the circuit - the atrium is on top, the ventricles are below.

3) Examination of the heart with a contrasted esophagus (the esophagus is normally located vertically and is adjacent to the arch of the left atrium for a considerable distance, which allows one to determine its condition). With enlargement of the left atrium, there is a displacement of the esophagus along an arc of large or small radius.

4) Tomography - clarifies the morphological features of the heart and large vessels.

5) X-ray kymography, electrokymography - methods of functional study of myocardial contractility.

6) X-ray cinematography - filming the work of the heart.

7) Catheterization of the cavities of the heart (determining blood oxygen saturation, measuring pressure, determining the minute and stroke volume of the heart).

8) Angiocardiography more accurately determines anatomical and hemodynamic disorders in heart defects (especially congenital ones).

X-ray data study plan

1. Study of the skeleton of the chest (attention is drawn to anomalies in the development of the ribs, spine, curvature of the latter, “abnormalities” of the ribs during coarctation of the aorta, signs of pulmonary emphysema, etc.).

2. Study of the diaphragm (position, mobility, fluid accumulation in the sinuses).

3. Study of the hemodynamics of the pulmonary circulation (the degree of bulging of the pulmonary artery cone, the condition of the roots of the lungs and pulmonary pattern, the presence of pleural lines and Kerley lines, focally infiltrative shadows, hemosiderosis).

4. X-ray morphological study of the cardiovascular shadow

a) position of the heart (oblique, vertical and horizontal).

b) heart shape (oval, mitral, triangular, aortic)

c) heart size. On the right, 1-1.5 cm from the edge of the spine, on the left, 1-1.5 cm not reaching the midclavicular line. We judge the upper limit by the so-called waist of the heart.

5. Determination of the functional characteristics of the heart and large vessels (pulsation, “yoke” symptom, systolic displacement of the esophagus, etc.).

Acquired heart defects

Relevance. The introduction of surgical treatment of acquired defects into surgical practice required radiologists to clarify them (stenosis, insufficiency, their predominance, the nature of hemodynamic disturbances).

Causes: almost all acquired defects are a consequence of rheumatism, rarely septic endocarditis; collagenosis, trauma, atherosclerosis, syphilis can also lead to heart disease.

Mitral valve insufficiency is more common than stenosis. This causes the valve flaps to shrink. Hemodynamic disturbances are associated with the absence of a period of closed valves. During ventricular systole, part of the blood returns to the left atrium. The latter is expanding. During diastole, a larger amount of blood returns to the left ventricle, which is why the latter has to work harder and hypertrophies. With a significant degree of insufficiency, the left atrium expands sharply, its wall sometimes becomes thinner to a thin sheet through which blood can be seen.

Violation of intracardiac hemodynamics with this defect is observed when 20-30 ml of blood is thrown into the left atrium. For a long time, no significant changes in circulatory disturbances in the pulmonary circle were observed. Congestion in the lungs occurs only in advanced stages - with left ventricular failure.

X-ray semiotics.

The shape of the heart is mitral (the waist is flattened or bulging). The main symptom is an enlargement of the left atrium, sometimes extending onto the right contour in the form of an additional third arch (symptom of “crossover”). The degree of enlargement of the left atrium is determined in the first oblique position in relation to the spine (1-III).

The contrasted esophagus deviates along an arc of large radius (more than 6-7 cm). There is an expansion of the tracheal bifurcation angle (up to 180) and a narrowing of the lumen of the right main bronchus. The third arc along the left contour prevails over the second. The aorta is of normal size and fills well. Among the X-ray functional symptoms, the most noteworthy are the “yoke” symptom (systolic expansion), systolic displacement of the esophagus, and Roesler’s symptom (transfer pulsation of the right root.

After surgery, all changes are eliminated.

Stenosis of the left mitral valve (fusion of the leaflets).

Hemodynamic disturbances are observed with a decrease in the mitral orifice by more than half (about one sq. cm). Normally, the mitral orifice is 4-6 sq. see, pressure in the left atrium cavity is 10 mm Hg. With stenosis, the pressure increases by 1.5-2 times. The narrowing of the mitral orifice prevents the expulsion of blood from the left atrium into the left ventricle, the pressure in which rises to 15-25 mm Hg, which complicates the outflow of blood from the pulmonary circulation. The pressure in the pulmonary artery increases (this is passive hypertension). Later, active hypertension is observed as a result of irritation of the baroreceptors of the endocardium of the left atrium and the mouth of the pulmonary veins. As a result of this, a reflex spasm of arterioles and larger arteries develops - the Kitaev reflex. This is the second barrier to blood flow (the first is the narrowing of the mitral valve). This increases the load on the right ventricle. Prolonged spasm of the arteries leads to cardiogenic pulmonary fibrosis.

Clinic. Weakness, shortness of breath, cough, hemoptysis. X-ray semiotics. The earliest and most characteristic sign is a violation of the hemodynamics of the pulmonary circulation - congestion in the lungs (expansion of the roots, increased pulmonary pattern, Kerley lines, septal lines, hemosiderosis).

X-ray symptoms. The heart has a mitral configuration due to the sharp bulging of the pulmonary artery cone (the second arch predominates over the third). There is hypertrophy of the left atrium. The coitrasted esophagus is deviated along a small radius arc. There is an upward displacement of the main bronchi (more than the left one), an increase in the angle of tracheal bifurcation. The right ventricle is enlarged, the left one is usually small. The aorta is hypoplastic. Heart contractions are calm. Calcification of the valves is often observed. During catheterization, an increase in pressure is noted (1-2 times higher than normal).

Aortic valve insufficiency

Hemodynamic disturbances with this heart defect are reduced to incomplete closure of the aortic valves, which during diastole leads to the return of 5 to 50% of the blood to the left ventricle. The result is dilation of the left ventricle due to hypertrophy. At the same time, the aorta expands diffusely.

The clinical picture includes palpitations, heart pain, fainting and dizziness. The difference in systolic and diastolic pressures is large (systolic pressure is 160 mm Hg, diastolic pressure is low, sometimes reaching 0). The carotid “dancing” symptom, Mussy’s symptom, and pallor of the skin are observed.

X-ray semiotics. An aortic configuration of the heart (deep, emphasized waist), enlargement of the left ventricle, and rounding of its apex are observed. All parts of the thoracic aorta expand evenly. Of the x-ray functional signs, noteworthy is the increase in the amplitude of heart contractions and increased pulsation of the aorta (pulse celer et altus). The degree of aortic valve insufficiency is determined by angiography (grade 1 - a narrow stream, in stage 4 - the entire cavity of the left ventricle is co-traced in diastole).

Aortic stenosis (narrowing more than 0.5-1 cm 2, normal 3 cm 2).

Hemodynamic disturbances result in obstructed blood outflow from the left ventricle into the aorta, which leads to prolongation of systole and increased pressure in the cavity of the left ventricle. The latter sharply hypertrophies. With decompensation, congestion occurs in the left atrium, and then in the lungs, then in the systemic circulation.

At the clinic, people notice heart pain, dizziness, and fainting. There is systolic tremor, pulse parvus et tardus. The defect remains compensated for a long time.

X-ray semiotics. Left ventricular hypertrophy, rounding and lengthening of its arch, aortic configuration, poststenotic dilation of the aorta (its ascending part). Heart contractions are tense and reflect difficult ejection of blood. Calcification of the aortic valves is quite common. With decompensation, mitralization of the heart develops (the waist is smoothed due to an enlargement of the left atrium). Angiography reveals narrowing of the aortic opening.

Pericarditis

Etiology: rheumatism, tuberculosis, bacterial infections.

1. fibrous pericarditis

2. effusion (exudative) pericarditis Clinic. Pain in the heart, pallor, cyanosis, shortness of breath, swelling of the veins of the neck.

The diagnosis of dry pericarditis is usually made based on clinical findings (pericardial friction rub). When fluid accumulates in the pericardial cavity (the minimum amount that can be detected x-ray is 30-50 ml), a uniform increase in the size of the heart is noted, the latter taking on a trapezoidal shape. The arcs of the heart are smoothed and not differentiated. The heart is widely adjacent to the diaphragm, its diameter prevails over its length. The cardiophrenic angles are sharp, the vascular bundle is shortened, and there is no congestion in the lungs. Displacement of the esophagus is not observed, cardiac pulsation is sharply weakened or absent, but preserved in the aorta.

Adhesive or compressive pericarditis is the result of fusion between both layers of the pericardium, as well as between the pericardium and the mediastinal pleura, which makes it difficult for the heart to contract. With calcification - “shell heart”.

Myocarditis

There are:

1. infectious-allergic

2. toxic-allergic

3. idiopathic myocarditis

Clinic. Pain in the heart, increased pulse rate with weak filling, rhythm disorder, signs of heart failure. At the apex of the heart there is a systolic murmur, muffled heart sounds. Noticeable congestion in the lungs.

The X-ray picture is due to myogenic dilatation of the heart and signs of decreased contractile function of the myocardium, as well as a decrease in the amplitude of heart contractions and their increase in frequency, which ultimately leads to stagnation in the pulmonary circulation. The main X-ray sign is enlargement of the ventricles of the heart (mainly the left), trapezoidal shape of the heart, the atria are enlarged to a lesser extent than the ventricles. The left atrium may extend onto the right circuit, deviation of the contrasted esophagus is possible, heart contractions are shallow and accelerated. When left ventricular failure occurs, stagnation appears in the lungs due to obstruction of blood outflow from the lungs. With the development of right ventricular failure, the superior vena cava expands and edema appears.

X-RAY STUDY OF THE GASTROINTESTINAL TRACT

Diseases of the digestive organs occupy one of the first places in the overall structure of morbidity, appeal and hospitalization. Thus, about 30% of the population have complaints from the gastrointestinal tract, 25.5% of patients are admitted to hospitals for emergency care, and pathology of the digestive organs accounts for 15% of overall mortality.

A further increase in diseases is predicted, mainly those in the development of which stress, dyskinetic, immunological and metabolic mechanisms play a role (peptic ulcer, colitis, etc.). The course of the disease becomes more severe. Often diseases of the digestive organs are combined with each other and diseases of other organs and systems; damage to the digestive organs is possible due to systemic diseases (scleroderma, rheumatism, diseases of the hematopoietic system, etc.).

The structure and function of all parts of the digestive canal can be studied using radiation methods. Optimal radiation diagnostic techniques have been developed for each organ. Establishing indications for radiation examination and its planning are carried out on the basis of anamnestic and clinical data. Endoscopic examination data is also taken into account, allowing one to examine the mucous membrane and obtain material for histological examination.

X-ray examination of the digestive canal occupies a special place in x-ray diagnostics:

1) recognition of diseases of the esophagus, stomach and colon is based on a combination of transillumination and photography. Here the importance of the experience of a radiologist is most clearly demonstrated,

2) examination of the gastrointestinal tract requires preliminary preparation (examination on an empty stomach, use of cleansing enemas, laxatives).

3) the need for artificial contrast (an aqueous suspension of barium sulfate, the introduction of air into the stomach cavity, oxygen into the abdominal cavity, etc.),

4) examination of the esophagus, stomach and colon is carried out mainly “from the inside” from the mucous membrane.

X-ray examination, due to its simplicity, universal accessibility and high efficiency, allows:

1) recognize most diseases of the esophagus, stomach and colon,

2) monitor the results of treatment,

3) carry out dynamic observations for gastritis, peptic ulcers and other diseases,

4) screen patients (fluorography).

Methods for preparing barium suspension. The success of X-ray examination depends, first of all, on the method of preparing the barium suspension. Requirements for an aqueous suspension of barium sulfate: maximum fineness, mass volume, adhesiveness and improvement of organoleptic properties. There are several ways to prepare barium suspension:

1. Boiling at the rate of 1:1 (per 100.0 BaS0 4 100 ml of water) for 2-3 hours.

2. Use of “Voronezh” type mixers, electric mixers, ultrasonic units, micro-pulverizers.

3. Recently, in order to improve conventional and double contrast, they have been trying to increase the mass volume of barium sulfate and its viscosity through various additives, such as distilled glycerin, polyglucin, sodium citrate, starch, etc.

4. Ready-made forms of barium sulfate: sulfobar and other proprietary preparations.

X-ray anatomy

The esophagus is a hollow tube 20-25 cm long, 2-3 cm wide. The contours are smooth and clear. 3 physiological constrictions. Sections of the esophagus: cervical, thoracic, abdominal. Folds - about longitudinal ones in the amount of 3-4. Projections of the study (direct, right and left oblique positions). The speed of movement of barium suspension through the esophagus is 3-4 seconds. Ways to slow down are to study in a horizontal position and take a thick paste-like mass. Research phases: tight filling, study of pneumorelief and mucosal relief.

Stomach. When analyzing the X-ray picture, it is necessary to have an idea of ​​the nomenclature of its various sections (cardiac, subcardial, body of the stomach, sinus, antrum, pyloric section, gastric vault).

The shape and position of the stomach depend on the constitution, gender, age, tone, and position of the person being examined. There is a hook-shaped stomach (vertically located stomach) in asthenics and a horn (horizontally located stomach) in hypersthenic individuals.

The stomach is located mostly in the left hypochondrium, but can move within a very wide range. The most variable position of the lower border (normally 2-4 cm above the crest of the iliac bones, but in thin people it is much lower, often above the entrance to the pelvis). The most fixed sections are the cardiac and pyloric. The width of the retrogastric space is of greater importance. Normally, it should not exceed the width of the lumbar vertebral body. During volumetric processes, this distance increases.

The relief of the gastric mucosa is formed by folds, interfold spaces and gastric fields. Folds are represented by stripes of enlightenment 0.50.8 cm wide. However, their sizes are highly variable and depend on gender, constitution, stomach tone, degree of distension, and mood. Gastric fields are defined as small filling defects on the surface of the folds due to elevations, at the top of which the ducts of the gastric glands open; their sizes normally do not exceed 3 mm and look like a thin mesh (the so-called thin relief of the stomach). With gastritis, it becomes rough, reaching a size of 5-8mm, resembling a “cobblestone street”.

Secretion of the gastric glands on an empty stomach is minimal. Normally, the stomach should be empty.

Stomach tone is the ability to embrace and hold a sip of barium suspension. There are normotonic, hypertonic, hypotonic and atonic stomachs. With normal tone, the barium suspension drops slowly, with low tone it drops quickly.

Peristalsis is the rhythmic contraction of the stomach walls. Attention is paid to rhythm, duration of individual waves, depth and symmetry. There are deep, segmenting, medium, superficial peristalsis and its absence. To stimulate peristalsis, it is sometimes necessary to resort to a morphine test (s.c. 0.5 ml of morphine).

Evacuation. During the first 30 minutes, half of the ingested aqueous suspension of barium sulfate is evacuated from the stomach. The stomach is completely freed from barium suspension within 1.5 hours. In a horizontal position on the back, emptying slows down sharply, while on the right side it accelerates.

Palpation of the stomach is normally painless.

The duodenum has the shape of a horseshoe, its length is from 10 to 30 cm, its width is from 1.5 to 4 cm. It has a bulb, upper horizontal, descending and lower horizontal parts. The pattern of the mucous membrane is feathery, inconsistent due to the Kerckring folds. In addition, there are small and

greater curvature, medial and lateral recesses, as well as the anterior and posterior walls of the duodenum.

Research methods:

1) usual classical examination (during examination of the stomach)

2) study under conditions of hypotension (probe and tubeless) using atropine and its derivatives.

The small intestine (ileum and jejunum) is examined similarly.

X-ray semiotics of diseases of the esophagus, stomach, colon (main syndromes)

X-ray symptoms of diseases of the digestive tract are extremely diverse. Its main syndromes:

1) change in the position of the organ (dislocation). For example, displacement of the esophagus by enlarged lymph nodes, a tumor, a cyst, the left atrium, displacement due to atelectasis, pleurisy, etc. The stomach and intestines are displaced by an enlarged liver, hiatal hernia, etc.;

2) deformation. Stomach in the form of a pouch, snail, retort, hourglass; duodenum - a trefoil-shaped bulb;

3) change in size: increase (achalasia of the esophagus, stenosis of the pyloroduodenal zone, Hirschsprung’s disease, etc.), decrease (infiltrating form of stomach cancer),

4) narrowing and expansion: diffuse (achalasia of the esophagus, gastric stenosis, intestinal obstruction, etc., local (tumor, scar, etc.);

5) filling defect. Usually determined by tight filling due to a space-occupying formation (exophytically growing tumor, foreign bodies, bezoars, fecal stone, food debris and

6) “niche” symptom - is the result of ulceration of the wall during an ulcer, tumor (cancer). A “niche” is distinguished on the contour in the form of a diverticulum-like formation and on the relief in the form of a “stagnant spot”;

7) changes in the folds of the mucosa (thickening, breakage, rigidity, convergence, etc.);

8) rigidity of the wall during palpation and inflation (the latter does not change);

9) change in peristalsis (deep, segmenting, superficial, lack of peristalsis);

10) pain on palpation).

Diseases of the esophagus

Foreign bodies. Research methodology (candling, survey photographs). The patient takes 2-3 sips of a thick barium suspension, then 2-3 sips of water. If a foreign body is present, traces of barium remain on its upper surface. Pictures are taken.

Achalasia (inability to relax) is a disorder of the innervation of the esophagogastric junction. X-ray semiotics: clear, even contours of narrowing, the “writing pen” symptom, pronounced suprastenotic expansion, elasticity of the walls, periodic “dropping” of barium suspension into the stomach, absence of a gas bubble of the stomach and the duration of the benign course of the disease.

Esophageal carcinoma. In an exophytically growing form of the disease, X-ray semiotics is characterized by 3 classic signs: filling defect, malignant relief, wall rigidity. In the infiltrative form, there is rigidity of the wall, uneven contours, and changes in the relief of the mucous membrane. It should be differentiated from cicatricial changes after burns, varicose veins, and cardiospasm. With all these diseases, peristalsis (elasticity) of the walls of the esophagus is preserved.

Stomach diseases

Stomach cancer. In men it ranks first in the structure of malignant tumors. In Japan it is a national catastrophe; in the USA there is a downward trend in the disease. The predominant age is 40-60 years.

Classification. The most common division of stomach cancer is:

1) exophytic forms (polypoid, mushroom-shaped, cauliflower-shaped, cup-shaped, plaque-shaped form with and without ulceration),

2) endophytic forms (ulcerative-infiltrative). The latter account for up to 60% of all gastric cancers,

3) mixed forms.

Stomach cancer metastasizes to the liver (28%), retroperitoneal lymph nodes (20%), peritoneum (14%), lungs (7%), bones (2%). Most often localized in the antrum (over 60%) and in the upper parts of the stomach (about 30%).

Clinic. Cancer often masquerades as gastritis, peptic ulcer, or cholelithiasis for years. Hence, for any gastric discomfort, X-ray and endoscopic examination is indicated.

X-ray semiotics. There are:

1) general signs (filling defect, malignant or atypical relief of the mucous membrane, absence of peristoglytics), 2) specific signs (in exophytic forms - a symptom of breakage of folds, flow around, splashing, etc.; in endfit forms - straightening of the lesser curvature, unevenness of the contour, deformation of the stomach; with total damage - a symptom of microgastrium.). In addition, with infiltrative forms, the filling defect is usually poorly expressed or absent, the relief of the mucous membrane almost does not change, the symptom of flat concave arcs (in the form of waves along the lesser curvature), the symptom of Gaudek's steps, is often observed.

X-ray semiotics of gastric cancer also depends on the location. When the tumor is localized in the gastric outlet, the following is noted:

1) elongation of the pyloric region by 2-3 times, 2) conical narrowing of the pyloric region occurs, 3) a symptom of undermining of the base of the pyloric region is observed 4) dilation of the stomach.

With cancer of the upper section (these are cancers with a long “silent” period) the following occur: 1) the presence of an additional shadow against the background of a gas bubble,

2) lengthening of the abdominal esophagus,

3) destruction of the mucosal relief,

4) the presence of edge defects,

5) flow symptom - “deltas”,

6) splashing symptom,

7) blunting of the Hiss angle (normally it is acute).

Cancers of the greater curvature are prone to ulceration - deep in the form of a well. However, any benign tumor in this area is prone to ulceration. Therefore, one must be careful with the conclusion.

Modern radiodiagnosis of gastric cancer. Recently, the number of cancers in the upper parts of the stomach has increased. Among all methods of radiological diagnostics, X-ray examination with tight filling remains the basic one. It is believed that diffuse forms of cancer today account for from 52 to 88%. In this form, cancer spreads predominantly intramural for a long time (from several months to one year or more) with minimal changes on the surface of the mucosa. Hence, endoscopy is often ineffective.

The leading radiological signs of intramural growing cancer should be considered uneven contour of the wall with tight filling (often one portion of barium suspension is not enough) and its thickening at the site of tumor infiltration with double contrast for 1.5 - 2.5 cm.

Due to the small extent of the lesion, peristalsis is often blocked by neighboring areas. Sometimes diffuse cancer manifests itself as a sharp hyperplasia of the folds of the mucosa. Often the folds converge or go around the affected area, resulting in the effect of no folds - (bald space) with the presence of a small barium spot in the center, caused not by ulceration, but by depression of the stomach wall. In these cases, methods such as ultrasound, CT, and MRI are useful.

Gastritis. Recently, in the diagnosis of gastritis, there has been a shift in emphasis towards gastroscopy with biopsy of the gastric mucosa. However, X-ray examination occupies an important place in the diagnosis of gastritis due to its accessibility and simplicity.

Modern recognition of gastritis is based on changes in the subtle relief of the mucous membrane, but double endogastric contrast is necessary to identify it.

Research methodology. 15 minutes before the test, 1 ml of a 0.1% atropine solution is injected subcutaneously or 2-3 aeron tablets are given (under the tongue). Then the stomach is inflated with a gas-forming mixture, followed by the intake of 50 ml of an aqueous suspension of barium sulfate in the form of an infusion with special additives. The patient is placed in a horizontal position and 23 rotational movements are made, followed by taking pictures on the back and in oblique projections. Then the usual examination is carried out.

Taking into account radiological data, several types of changes in the fine relief of the gastric mucosa are distinguished:

1) finely reticulated or granular (areolas 1-3 mm),

2) modular - (areola size 3-5 mm),

3) coarse nodular - (the size of the areolas is more than 5 mm, the relief is in the form of a “cobblestone street”). In addition, in the diagnosis of gastritis, such signs as the presence of fluid on an empty stomach, rough relief of the mucous membrane, diffuse pain on palpation, pyloric spasm, reflux, etc. are taken into account.

Benign tumors. Among them, polyps and leiomyomas are of greatest practical importance. A single polyp with tight filling is usually defined as a round filling defect with clear, even contours measuring 1-2 cm. Folds of the mucosa bypass the filling defect or the polyp is located on the fold. The folds are soft, elastic, palpation is painless, peristalsis is preserved. Leiomyomas differ from the X-ray semiotics of polyps in the preservation of mucosal folds and significant size.

Bezoars. It is necessary to distinguish between stomach stones (bezoars) and foreign bodies (swallowed bones, fruit pits, etc.). The term bezoar is associated with the name of a mountain goat, in whose stomach stones from licked wool were found.

For several millennia, the stone was considered an antidote and was valued higher than gold, as it supposedly brings happiness, health, and youth.

The nature of stomach bezoars is different. The most common:

1) phytobezoars (75%). Formed when eating a large amount of fruits containing a lot of fiber (unripe persimmon, etc.),

2) sebobezoars - occur when eating large amounts of fat with a high melting point (lamb fat),

3) trichobezoars - found in people who have the bad habit of biting off and swallowing hair, as well as in people caring for animals,

4) pixobesoars - the result of chewing resins, gum, gum,

5) shellac-bezoars - when using alcohol substitutes (alcohol varnish, palette, nitro varnish, nitro glue, etc.),

6) bezoars can occur after vagotomies,

7) bezoars consisting of sand, asphalt, starch and rubber are described.

Bezoars usually occur clinically under the guise of a tumor: pain, vomiting, weight loss, palpable swelling.

X-ray bezoars are defined as a filling defect with uneven contours. Unlike cancer, the filling defect shifts during palpation, peristalsis and the relief of the mucous membrane are preserved. Sometimes a bezoar simulates lymphosarcoma, gastric lymphoma.

Peptic ulcer of the stomach and duodenum is extremely common. 7-10% of the world's population suffers. Annual exacerbations are observed in 80% of patients. In the light of modern concepts, this is a general chronic, cyclical, recurrent disease, which is based on complex etiological and pathological mechanisms of ulcer formation. This is the result of the interaction of aggression and defense factors (too strong aggression factors with weak defense factors). The aggression factor is peptic proteolysis during prolonged hyperchlorhydria. The protective factors include the mucous barrier, i.e. high regenerative ability of the mucosa, stable nervous trophism, good vascularization.

During a peptic ulcer, three stages are distinguished: 1) functional disorders in the form of gastroduodenitis, 2) the stage of a formed ulcerative defect and 3) the stage of complications (penetration, perforation, bleeding, deformation, degeneration into cancer).

X-ray manifestations of gastroduodenitis: hypersecretion, impaired motility, restructuring of the mucosa in the form of coarse expanded cushion-shaped folds, rough microrelief, spasm or gaping of the transvaricus, duodenogastric reflux.

Signs of peptic ulcer disease are reduced to the presence of a direct sign (a niche on the contour or on the relief) and indirect signs. The latter, in turn, are divided into functional and morphological. Functional ones include hypersecretion, pyloric spasm, slower evacuation, local spasm in the form of a “pointing finger” on the opposite wall, local hypermatility, changes in peristalsis (deep, segmented), tone (hypertonicity), duodenogastric reflux, gastroesophageal reflux, etc. Morphological signs are filling defect due to the inflammatory shaft around the niche, convergence of folds (during scarring of the ulcer), cicatricial deformation (stomach in the form of a pouch, hourglass, snail, cascade, duodenal bulb in the form of a trefoil, etc.).

More often, the ulcer is localized in the area of ​​the lesser curvature of the stomach (36-68%) and proceeds relatively favorably. In the antrum, ulcers are also located relatively often (9-15%) and are found, as a rule, in young people, accompanied by signs of duodenal ulcer (late hunger pain, heartburn, vomiting, etc.). X-ray diagnosis of them is difficult due to pronounced motor activity, rapid passage of barium suspension, and difficulty in removing the ulcer to the contour. Often complicated by penetration, bleeding, perforation. In the cardiac and subcardial region, ulcers are localized in 2-18% of cases. Usually found in older people and present certain difficulties for endoscopic and radiological diagnosis.

The shape and size of the niches in peptic ulcer disease are variable. Often (13-15%) there is a multiplicity of lesions. The frequency of identifying a niche depends on many reasons (location, size, presence of fluid in the stomach, filling of the ulcer with mucus, blood clot, food debris) and ranges from 75 to 93%. Quite often there are giant niches (over 4 cm in diameter), penetrating ulcers (2-3 niches of complexity).

An ulcerative (benign) niche should be differentiated from a cancerous one. Cancer niches have a number of features:

1) the predominance of the longitudinal size over the transverse,

2) ulceration is located closer to the distal edge of the tumor,

3) the niche has an irregular shape with bumpy outlines, usually does not extend beyond the contour, the niche is painless on palpation, plus signs characteristic of a cancerous tumor.

Ulcer niches are usually

1) located near the lesser curvature of the stomach,

2) extend beyond the contours of the stomach,

3) have a cone shape,

4) the diameter is larger than the length,

5) painful on palpation, plus signs of peptic ulcer disease.

RADIATION STUDY OF THE MUSCULOSKETAL SYSTEM

In 1918, the world's first laboratory for studying the anatomy of humans and animals using x-rays was opened at the State X-ray Radiological Institute in Petrograd.

The X-ray method made it possible to obtain new data on the anatomy and physiology of the musculoskeletal system: to study the structure and function of bones and joints intravitally, in the whole organism, when a person is exposed to various environmental factors.

A group of domestic scientists made a great contribution to the development of osteopathology: S.A. Reinberg, D.G. Rokhlin, PA. Dyachenko and others.

The X-ray method is the leading one in the study of the musculoskeletal system. Its main techniques are: radiography (in 2 projections), tomography, fistulography, images with magnified X-ray images, contrast techniques.

An important method in the study of bones and joints is X-ray computed tomography. Magnetic resonance imaging should also be recognized as a valuable method, especially when examining bone marrow. To study metabolic processes in bones and joints, radionuclide diagnostic methods are widely used (bone metastases are detected before X-ray examination by 3-12 months). Sonography opens up new ways to diagnose diseases of the musculoskeletal system, especially in the diagnosis of foreign bodies that weakly absorb X-rays, articular cartilage, muscles, ligaments, tendons, accumulation of blood and pus in the periosseous tissues, periarticular cysts, etc.

Radiation research methods allow:

1. monitor the development and formation of the skeleton,

2. assess the morphology of the bone (shape, outline, internal structure, etc.),

3. recognize traumatic injuries and diagnose various diseases,

4. judge functional and pathological changes (vibration disease, marching foot, etc.),

5. study the physiological processes in bones and joints,

6. evaluate the response to various factors (toxic, mechanical, etc.).

Radiation anatomy.

Maximum structural strength with minimal waste of building material is characterized by the anatomical features of the structure of bones and joints (the femur can withstand a load along the longitudinal axis of 1.5 tons). Bone is a favorable object for x-ray examination, because contains many inorganic substances. Bone consists of bone beams and trabeculae. In the cortical layer they are closely adjacent, forming a uniform shadow, in the epiphyses and metaphyses they are located at some distance, forming a spongy substance, with bone marrow tissue between them. The relationship between the bone beams and the medullary spaces creates the bone structure. Hence, in the bone there are: 1) a dense compact layer, 2) a spongy substance (cellular structure), 3) a medullary canal in the center of the bone in the form of a lightening. There are tubular, short, flat and mixed bones. In each tubular bone, there are epiphysis, metaphysis and diaphysis, as well as apophyses. The epiphysis is an articular part of the bone covered with cartilage. In children it is separated from the metaphysis by the growth cartilage, in adults by the metaphyseal suture. Apophyses are additional points of ossification. These are the attachment points for muscles, ligaments and tendons. The division of bone into epiphysis, metaphysis and diaphysis is of great clinical importance, because some diseases have a favorite localization (osteomyelitis in the metadiaphysis, tuberculosis affects the pineal gland, Ewing's sarcoma is localized in the diaphysis, etc.). Between the connecting ends of the bones there is a light stripe, the so-called x-ray joint space, caused by cartilage tissue. Good photographs show the joint capsule, joint capsule, and tendon.

Development of the human skeleton.

In its development, the bone skeleton goes through membranous, cartilaginous and bony stages. During the first 4-5 weeks, the fetal skeleton is webbed and not visible on photographs. Developmental disorders during this period lead to changes that make up the group of fibrous dysplasias. At the beginning of the 2nd month of uterine life of the fetus, the membranous skeleton is replaced by cartilaginous skeleton, which also does not appear on radiographs. Developmental disorders lead to cartilaginous dysplasia. Starting from the 2nd month and up to 25 years, the cartilaginous skeleton is replaced by bone. By the end of the prenatal period, most of the skeleton is osseous and the bones of the fetus are clearly visible on photographs of the pregnant abdomen.

The skeleton of newborns has the following features:

1. the bones are small,

2. they are structureless,

3. at the ends of most bones there are no ossification nuclei yet (the epiphyses are not visible),

4. X-ray joint spaces are large,

5. large brain skull and small facial skull,

6. relatively large orbits,

7. weakly expressed physiological curves of the spine.

The growth of the bone skeleton occurs due to the growth zones in length, in thickness - due to the periosteum and endosteum. At the age of 1-2 years, differentiation of the skeleton begins: ossification points appear, bones synostose, increase in size, and curvatures of the spine appear. The skeleton of the skeleton ends by the age of 20-25. Between 20-25 years and up to 40 years of age, the osteoarticular apparatus is relatively stable. From the age of 40, involutive changes begin (dystrophic changes in articular cartilage), thinning of the bone structure, the appearance of osteoporosis and calcification at the attachment points of ligaments, etc. The growth and development of the osteoarticular system is influenced by all organs and systems, especially the parathyroid glands, pituitary gland and central nervous system.

Plan for studying radiographs of the osteoarticular system. Need to evaluate:

1) shape, position, size of bones and joints,

2) state of the circuits,

3) the state of the bone structure,

4) identify the state of growth zones and ossification nuclei (in children),

5) study the condition of the articular ends of the bones (X-ray joint space),

6) assess the condition of soft tissues.

X-ray semiotics of bone and joint diseases.

The X-ray picture of bone changes in any pathological process consists of 3 components: 1) changes in shape and size, 2) changes in contours, 3) changes in structure. In most cases, the pathological process leads to bone deformation, consisting of lengthening, shortening and curvature, to a change in volume in the form of thickening due to periostitis (hyperostosis), thinning (atrophy) and swelling (cyst, tumor, etc.).

Changes in bone contours: Bone contours are normally characterized by evenness (smoothness) and clarity. Only in the places of attachment of muscles and tendons, in the area of ​​tubercles and tuberosities, the contours are rough. Lack of clarity of contours, their unevenness is often the result of inflammatory or tumor processes. For example, bone destruction as a result of the germination of cancer of the oral mucosa.

All physiological and pathological processes occurring in the bones are accompanied by changes in the bone structure, a decrease or increase in bone beams. A peculiar combination of these phenomena creates in the X-ray image such pictures that are inherent in certain diseases, allowing them to be diagnosed, the phase of development, and complications to be determined.

Structural changes in bone can be in the nature of physiological (functional) and pathological restructuring caused by various reasons (traumatic, inflammatory, tumor, degenerative-dystrophic, etc.).

There are over 100 diseases that are accompanied by changes in the mineral content of the bones. The most common is osteoporosis. This is a decrease in the number of bone beams per unit volume of bone. In this case, the overall volume and shape of the bone usually remain unchanged (if there is no atrophy).

There are: 1) idiopathic osteoporosis, which develops for no apparent reason and 2) with various diseases of internal organs, endocrine glands, as a result of taking medications, etc. In addition, osteoporosis can be caused by nutritional disorders, weightlessness, alcoholism, unfavorable working conditions, prolonged immobilization , exposure to ionizing radiation, etc.

Hence, depending on the causes, osteoporosis is distinguished as physiological (involutive), functional (from inactivity) and pathological (from various diseases). Based on prevalence, osteoporosis is divided into: 1) local, for example, in the area of ​​a jaw fracture after 5-7 days, 2) regional, in particular, involving the area of ​​the lower jaw branch with osteomyelitis 3) widespread, when the area of ​​the body and jaw branches is affected, and 4) systemic, accompanied by damage to the entire bone skeleton.

Depending on the X-ray picture, there are: 1) focal (spotty) and 2) diffuse (uniform) osteoporosis. Spotty osteoporosis is defined as foci of rarefaction of bone tissue ranging in size from 1 to 5 mm (reminiscent of moth-eaten matter). Occurs with osteomyelitis of the jaws in the acute phase of its development. Diffuse (glassy) osteoporosis is more often observed in the jaw bones. In this case, the bone becomes transparent, the structure is broadly looped, the cortical layer becomes thinner in the form of a very narrow dense line. It is observed in old age, with hyperparathyroid osteodystrophy and other systemic diseases.

Osteoporosis can develop within a few days and even hours (with causalgia), with immobilization - in 10-12 days, with tuberculosis it takes several months and even years. Osteoporosis is a reversible process. Once the cause is eliminated, the bone structure is restored.

Hypertrophic osteoporosis is also distinguished. At the same time, against the background of general transparency, individual bone beams appear hypertrophied.

Osteosclerosis is a symptom of bone diseases that are quite common. Accompanied by an increase in the number of bone beams per unit volume of bone and a decrease in interblock bone marrow spaces. At the same time, the bone becomes denser and structureless. The cortex expands, the medullary canal narrows.

There are: 1) physiological (functional) osteosclerosis, 2) idiopathic as a result of developmental anomalies (with marbled disease, myelorheostosis, osteopoikilia) and 3) pathological (post-traumatic, inflammatory, toxic, etc.).

Unlike osteoporosis, osteosclerosis requires quite a long time (months, years) to occur. The process is irreversible.

Destruction is the destruction of bone with its replacement by pathological tissue (granulation, tumor, pus, blood, etc.).

There are: 1) inflammatory destruction (osteomyelitis, tuberculosis, actinomycosis, syphilis), 2) tumor (osteogenic sarcoma, reticulosarcoma, metastases, etc.), 3) degenerative-dystrophic (hyperparathyroid osteodystrophy, osteoarthritis, cysts in deforming osteoarthritis, etc.) .

X-ray, regardless of the reasons, destruction is manifested by clearing. It can appear small or large focal, multifocal and extensive, superficial and central. Therefore, to establish the causes, a thorough analysis of the source of destruction is necessary. It is necessary to determine the location, size, number of lesions, the nature of the contours, the pattern and reaction of the surrounding tissues.

Osteolysis is the complete resorption of bone without its replacement by any pathological tissue. This is the result of deep neurotrophic processes in diseases of the central nervous system, damage to peripheral nerves (tabes dorsalis, syringomyelia, scleroderma, leprosy, lichen planus, etc.). The peripheral (end) parts of the bone (nail phalanges, articular ends of large and small joints) undergo resorption. This process is observed in scleroderma, diabetes mellitus, traumatic injuries, and rheumatoid arthritis.

Osteonecrosis and sequestration are a frequent accompaniment of bone and joint diseases. Osteonecrosis is the necrosis of a section of bone due to malnutrition. At the same time, the amount of liquid elements in the bone decreases (the bone “dries out”) and radiographically such an area is determined in the form of darkening (compaction). There are: 1) aseptic osteonekoosis (with osteochondropathy, thrombosis and embolism of blood vessels), 2) septic (infectious), occurring with osteomyelitis, tuberculosis, actinomycosis and other diseases.

The process of delimiting an area of ​​osteonecrosis is called sequestration, and the rejected area of ​​bone is called sequestration. There are cortical and spongy sequestra, regional, central and total. Sequestration is characteristic of osteomyelitis, tuberculosis, actinomycosis and other diseases.

Changes in bone contours are often associated with periosteal layers (periostitis and periostosis).

4) functional-adaptive periostitis. The last two forms should be called per gostoses.

When identifying periosteal changes, you should pay attention to their localization, extent and nature of the layers. Most often, periostitis is detected in the area of ​​the lower jaw.

According to their shape, linear, layered, fringed, spicule-shaped periostitis (periostosis) and periostitis in the form of a visor are distinguished.

Linear periostitis in the form of a thin strip parallel to the cortical layer of the bone usually occurs in inflammatory diseases, injuries, Ewing's sarcoma and characterizes the initial stages of the disease.

Layered (bulbous) periostitis is radiologically determined in the form of several linear shadows and usually indicates a jerky course of the process (Ewing's sarcoma, chronic osteomyelitis, etc.).

When linear layers are destroyed, fringed (broken) periostitis occurs. In its pattern it resembles pumice and is considered characteristic of syphilis. With tertiary syphilis, the following may be observed: and lace (comb-like) periostitis.

Spiculous (needle-shaped) periostitis is considered pathognomonic for malignant tumors. Occurs in osteogenic sarcoma as a result of tumor release into soft tissue.

Changes in X-ray joint space. which is a reflection of articular cartilage and can be in the form of narrowing due to the destruction of cartilage tissue (tuberculosis, purulent arthritis, osteoarthritis), expansion due to an increase in cartilage (osteochondropathia), as well as subluxation. When fluid accumulates in the joint cavity, the X-ray joint space does not widen.

Changes in soft tissues are very diverse and should also be the object of close X-ray examination (tumor, inflammatory, traumatic changes).

Damage to bones and joints.

Objectives of X-ray examination:

1. confirm the diagnosis or reject it,

2. determine the nature and type of fracture,

3. determine the number and degree of displacement of fragments,

4. detect dislocation or subluxation,

5. identify foreign bodies,

6. establish the correctness of medical manipulations,

7. exercise control during the healing process. Signs of a fracture:

1. fracture line (in the form of clearing and compaction) - transverse, longitudinal, oblique, intra-articular, etc. fractures.

2. displacement of fragments: widthwise or lateral, lengthwise or longitudinal (with entry, divergence, wedging of fragments), axially or angularly, along the periphery (spiral-shaped). The displacement is determined by the peripheral fragment.

Features of fractures in children are usually subperiosteal, in the form of a crack and epiphysiolysis. In elderly people, fractures are usually comminuted in nature, with intra-articular localization, with displacement of fragments; healing is slow, often complicated by the development of a pseudarthrosis.

Signs of vertebral body fractures: 1) wedge-shaped deformity with the tip directed anteriorly, compaction of the vertebral body structure, 2) the presence of a shadow of a hematoma around the affected vertebra, 3) posterior displacement of the vertebra.

There are traumatic and pathological fractures (as a result of destruction). Differential diagnosis is often difficult.

Monitoring fracture healing. During the first 7-10 days, the callus is of a connective tissue nature and is not visible on photographs. During this period, there is an expansion of the fracture line and rounding and smoothing of the ends of the broken bones. From 20-21 days, more often after 30-35 days, islands of calcification appear in the callus, clearly visible on radiographs. Complete calcification takes 8 to 24 weeks. Hence, radiographically it is possible to identify: 1) a slowdown in the formation of callus, 2) its excessive development, 3) Normally, the periosteum is not visible on the images. To identify it, compaction (calcification) and exfoliation are necessary. Periostitis is a response of the periosteum to one or another irritation. In children, radiological signs of periostitis are determined at 7-8 days, in adults - at 12-14 days.

Depending on the cause, they are distinguished: 1) aseptic (in case of injury), 2) infectious (osteomyelitis, tuberculosis, syphilis), 3) irritative-toxic (tumors, suppurative processes) and emerging or formed false joint. In this case, there is no callus, the ends of the fragments are rounded and polished, and the medullary canal is closed.

Restructuring of bone tissue under the influence of excessive mechanical force. Bone is an extremely plastic organ that is rebuilt throughout life, adapting to living conditions. This is a physiological change. When the bone is presented with disproportionately increased demands, pathological restructuring develops. This is a breakdown of the adaptive process, disadaptation. Unlike a fracture, in this case there is repeated traumatization - the total effect of frequently repeated blows and shocks (the metal cannot withstand it either). Special zones of temporary disintegration arise - zones of restructuring (Loozerov zones), zones of enlightenment, which are little known to practical doctors and are often accompanied by diagnostic errors. Most often the skeleton of the lower extremities (foot, thigh, lower leg, pelvic bones) is affected.

The clinical picture distinguishes 4 periods:

1. within 3-5 weeks (after drill training, jumping, working with a jackhammer, etc.) pain, lameness, and pastiness appear over the site of reconstruction. There are no radiological changes during this period.

2. after 6-8 weeks, lameness, severe pain, swelling and local swelling increase. A tender periosteal reaction (usually spindle-shaped) appears on the images.

3. 8-10 weeks. Severe lameness, pain, severe swelling. X-ray - pronounced periostosis of a spindle-shaped form, in the center of which there is a “fracture” line passing through the diameter of the bone and a poorly traced medullary canal.

4. recovery period. Lameness disappears, there is no swelling, radiographically the periosteal zone is reduced, the bone structure is restored. Treatment is first rest, then physiotherapy.

Differential diagnosis: osteogenic sacroma, osteomyelitis, osteodosteoma.

A typical example of pathological restructuring is marching foot (Deutschlander's disease, recruits' fracture, overloaded foot). The diaphysis of the 2nd-3rd metatarsal bone is usually affected. The clinic is described above. X-ray semiotics boils down to the appearance of a clearing line (fracture) and muff-like periostitis. The total duration of the disease is 3-4 months. Other types of pathological restructuring.

1. Multiple Loozer zones in the form of triangular notches along the anteromedial surfaces of the tibia (in schoolchildren during the holidays, athletes during excessive training).

2. Lacunar shadows located subperiosteally in the upper third of the tibia.

3. Bands of osteosclerosis.

4. In the form of an edge defect

Changes in bones during vibration occur under the influence of rhythmically operating pneumatic and vibrating tools (miners, miners, asphalt road repairmen, some branches of the metalworking industry, pianists, typists). The frequency and intensity of changes depends on the length of service (10-15 years). The risk group includes persons under 18 years of age and over 40 years of age. Diagnostic methods: rheovasography, thermography, cappilaroscopy, etc.

Main radiological signs:

1. Islands of compaction (enostoses) can occur in all bones of the upper limb. The shape is irregular, the contours are uneven, the structure is uneven.

2. racemose formations are more often found in the bones of the hand (wrist) and look like a clearing 0.2-1.2 cm in size, round in shape with a rim of sclerosis around.

3. osteoporosis.

4. osteolysis of the terminal phalanges of the hand.

5. deforming osteoarthritis.

6. changes in soft tissues in the form of paraosseous calcifications and ossifications.

7. deforming spondylosis and osteochondrosis.

8. osteonecrosis (usually the lunate bone).

CONTRAST METHODS OF RESEARCH IN RADIATION DIAGNOSTICS

Obtaining an X-ray image is associated with uneven absorption of rays in the object. For the latter to receive an image, it must have a different structure. Hence, some objects, such as soft tissues and internal organs, are not visible on regular photographs and require the use of contrast media (CM) for their visualization.

Soon after the discovery of X-rays, ideas for obtaining images of various tissues using CS began to develop. One of the first CSs to achieve success were iodine compounds (1896). Subsequently, buroselectan (1930) for liver research, containing one iodine atom, found widespread use in clinical practice. Uroselektan was the prototype of all CS created later for the study of the urinary system. Soon, uroselectan (1931) appeared, already containing two iodine molecules, which made it possible to improve image contrast while being well tolerated by the body. In 1953, a triiodinated urography drug appeared, which turned out to be useful for angiography.

In modern visualized diagnostics, CS provide a significant increase in the information content of x-ray examination methods, X-ray CT, MRI and ultrasound diagnostics. All CS have one purpose - to increase the difference between different structures in terms of their ability to absorb or reflect electromagnetic radiation or ultrasound. To fulfill their task, CS must reach a certain concentration in tissues and be harmless, which, unfortunately, is impossible, since they often lead to undesirable consequences. Hence, the search for highly effective and harmless CS continues. The urgency of the problem increases with the advent of new methods (CT, MRI, ultrasound).

Modern requirements for KS: 1) good (sufficient) image contrast, i.e. diagnostic effectiveness, 2) physiological validity (organ specificity, elimination along the route from the body), 3) general availability (cost-effectiveness), 4) harmlessness (lack of irritation, toxic damage and reactions), 5) ease of administration and speed of elimination from the body.

The routes of CS administration are extremely varied: through natural openings (lacrimal puncta, external auditory canal, through the mouth, etc.), through postoperative and pathological openings (fistula tracts, anastomosis, etc.), through the walls of the s/s and lymphatic system (puncture, catheterization, section, etc.), through the walls of pathological cavities (cysts, abscesses, cavities, etc.), through the walls of natural cavities, organs, ducts (puncture, trepanation), introduction into cellular spaces (puncture).

Currently, all CS are divided into:

1. X-ray

2. MRI - contrast agents

3. Ultrasound - contrast agents

4. fluorescent (for mammography).

From a practical point of view, it is advisable to subdivide CS into: 1) traditional X-ray and CT contrast agents, as well as non-traditional ones, in particular, those created on the basis of barium sulfate.

Traditional X-ray contrast agents are divided into: a) negative (air, oxygen, carbon dioxide, etc.), b) positive, absorbing X-rays well. Contrast agents of this group attenuate radiation 50-1000 times compared to soft tissues. Positive CS, in turn, are divided into water-soluble (iodine preparations) and water-insoluble (barium sulfate).

Iodine contrast agents - their tolerance by patients is explained by two factors: 1) osmolarity and 2) chemotoxicity, including ionic exposure. To reduce osmolarity, it was proposed: a) the synthesis of ionic dimeric CS and b) the synthesis of nonionic monomers. For example, ionic dimeric CS were hyperosmolar (2000 m mol/l), while ionic dimers and nonionic monomers already had an osmolarity significantly lower (600-700 m mol/l), and their chemotoxicity also decreased. The nonionic monomer “Omnipak” began to be used in 1982 and its fate has been brilliant. Of the nonionic dimers, Vizipak is the next step in the development of ideal CS. It has isosmolarity, i.e. its osmolarity is equal to blood plasma (290 m mol/l). Nonionic dimers, more than any other CS at this stage of development of science and technology, correspond to the concept of “Ideal contrast agents.”

KS for RKT. In connection with the widespread use of RCT, selective contrast CS began to be developed for various organs and systems, in particular, the kidneys and liver, since modern water-soluble cholecystographic and urographic CS turned out to be insufficient. To a certain extent, Josefanat meets the requirements of the CS for RCT. This CS is selectively concentrated in functional hepatocytes and can be used for tumors and cirrhosis of the liver. Good reviews are also received when using Vizipak, as well as capsulated Iodixanol. All these CT scans are promising for visualizing liver megastases, liver carcinomas, and hemangiomas.

Both ionic and non-ionic (to a lesser extent) can cause reactions and complications. Side effects of iodine-containing CS are a serious problem. According to international statistics, kidney damage by the CS remains one of the main types of iatrogenic renal failure, accounting for about 12% of hospital-acquired acute renal failure. Vascular pain with intravenous administration of the drug, a feeling of heat in the mouth, a bitter taste, chills, redness, nausea, vomiting, abdominal pain, increased heart rate, a feeling of heaviness in the chest - this is not a complete list of the irritating effects of the CS. There may be cardiac and respiratory arrest, and in some cases death occurs. Hence, there are three degrees of severity of adverse reactions and complications:

1) mild reactions (“hot waves”, skin hyperemia, nausea, slight tachycardia). No drug therapy is required;

2) moderate degree (vomiting, rash, collapse). S/s and antiallergic drugs are prescribed;

3) severe reactions (anuria, transverse myelitis, respiratory and cardiac arrest). It is impossible to predict reactions in advance. All proposed prevention methods turned out to be ineffective. Recently, a test “at the tip of a needle” has been proposed. In some cases, premedication is recommended, in particular with prednisone and its derivatives.

Currently, the quality leaders among CS are “Omnipak” and “Ultravist”, which have high local tolerability, overall low toxicity, minimal hemodynamic effects and high image quality. Used for urography, angiography, myelography, gastrointestinal examination, etc.

X-ray contrast agents based on barium sulfate. The first reports on the use of an aqueous suspension of barium sulfate as a CS belong to R. Krause (1912). Barium sulfate absorbs X-rays well, mixes easily in various liquids, does not dissolve and does not form various compounds with the secretions of the digestive canal, is easily crushed and allows you to obtain a suspension of the required viscosity, and adheres well to the mucous membrane. For more than 80 years, the method of preparing an aqueous suspension of barium sulfate has been improved. Its main requirements boil down to maximum concentration, fineness and adhesiveness. In this regard, several methods have been proposed for preparing an aqueous suspension of barium sulfate:

1) Boiling (1 kg of barium is dried, sifted, 800 ml of water is added and boiled for 10-15 minutes. Then passed through cheesecloth. This suspension can be stored for 3-4 days);

2) To achieve high dispersion, concentration and viscosity, high-speed mixers are now widely used;

3) Viscosity and contrast are greatly influenced by various stabilizing additives (gelatin, carboxymethylcellulose, flax seed mucilage, starch, etc.);

4) Use of ultrasonic installations. In this case, the suspension remains homogeneous and practically barium sulfate does not settle for a long time;

5) The use of patented domestic and foreign drugs with various stabilizing substances, astringents, and flavoring additives. Among them, barotrast, mixobar, sulfobar, etc. deserve attention.

The effectiveness of double contrast increases to 100% when using the following composition: barium sulfate - 650 g, sodium citrate - 3.5 g, sorbitol - 10.2 g, antifosmilan -1.2 g, water - 100 g.

A suspension of barium sulfate is harmless. However, if it gets into the abdominal cavity and respiratory tract, toxic reactions are possible, and with stenosis, the development of obstruction.

Non-traditional iodine-containing CSs include magnetic liquids - ferromagnetic suspensions that move in organs and tissues by an external magnetic field. Currently, there are a number of compositions based on ferrites of magnesium, barium, nickel, copper, suspended in a liquid aqueous carrier containing starch, polyvinyl alcohol and other substances with the addition of powdered metal oxides of barium, bismuth and other chemicals. Special devices with a magnetic device have been manufactured that are capable of controlling these CS.

It is believed that ferromagnetic preparations can be used in angiography, bronchography, salpingography, and gastrography. This method has not yet received widespread use in clinical practice.

Recently, among non-traditional contrast agents, biodegradable contrast agents deserve attention. These are drugs based on liposomes (egg lecithin, cholesterol, etc.), deposited selectively in various organs, in particular in the RES cells of the liver and spleen (iopamidol, metrizamide, etc.). Brominated liposomes for CT have been synthesized and excreted by the kidneys. CSs based on perfluorocarbons and other non-traditional chemical elements, such as tantalum, tungsten, and molybdenum, have been proposed. It is too early to talk about their practical application.

Thus, in modern clinical practice, mainly two classes of X-ray CS are used - iodinated and barium sulfate.

Paramagnetic CS for MRI. Magnevist is currently widely used as a paramagnetic contrast agent for MRI. The latter shortens the spin-lattice relaxation time of excited atomic nuclei, which increases the signal intensity and increases the tissue image contrast. After intravenous administration, it is rapidly distributed in the extracellular space. It is excreted from the body mainly by the kidneys using glomerular filtration.

Application area. The use of Magnevist is indicated in the study of central nervous system organs, in order to detect a tumor, as well as for differential diagnosis in cases of suspected brain tumor, acoustic neuroma, glioma, tumor metastases, etc. With the help of Magnevist, the degree of damage to the brain and spinal cord is reliably determined for multiple sclerosis and monitor the effectiveness of the treatment. Magnevist is used in the diagnosis and differential diagnosis of spinal cord tumors, as well as to identify the prevalence of tumors. “Magnevist” is also used for MRI of the whole body, including examination of the facial skull, neck area, chest and abdominal cavities, mammary glands, pelvic organs, and musculoskeletal system.

Fundamentally new CS have now been created and become available for ultrasound diagnostics. “Ekhovist” and “Levovost” deserve attention. They are a suspension of galactose microparticles containing air bubbles. These drugs make it possible, in particular, to diagnose diseases that are accompanied by hemodynamic changes in the right side of the heart.

Currently, thanks to the widespread use of radiopaque, paramagnetic agents and those used in ultrasound examinations, the possibilities for diagnosing diseases of various organs and systems have expanded significantly. Research continues to create new CS that are highly effective and safe.

FUNDAMENTALS OF MEDICAL RADIOLOGY

Today we are witnessing the ever-accelerating progress of medical radiology. Every year, new methods of obtaining images of internal organs and methods of radiation therapy are being introduced into clinical practice.

Medical radiology is one of the most important medical disciplines of the atomic age. It was born at the turn of the 19th and 20th centuries, when people learned that in addition to the familiar world we see, there is a world of extremely small quantities, fantastic speeds and unusual transformations. This is a relatively young science, the date of its birth is precisely indicated thanks to the discoveries of the German scientist W. Roentgen; (November 8, 1895) and the French scientist A. Becquerel (March 1996): discoveries of X-rays and the phenomena of artificial radioactivity. Becquerel's message determined the fate of P. Curie and M. Skladovskaya-Curie (they isolated radium, radon, and polonium). Rosenford's work was of exceptional importance for radiology. By bombarding nitrogen atoms with alpha particles, he obtained isotopes of oxygen atoms, i.e., the transformation of one chemical element into another was proven. This was the “alchemist” of the 20th century, the “crocodile”. He discovered the proton and neutron, which made it possible for our compatriot Ivanenko to create a theory of the structure of the atomic nucleus. In 1930, a cyclotron was built, which allowed I. Curie and F. Joliot-Curie (1934) to obtain a radioactive isotope of phosphorus for the first time. From that moment on, the rapid development of radiology began. Among domestic scientists, it is worth noting the studies of Tarkhanov, London, Kienbeck, Nemenov, who made a significant contribution to clinical radiology.

Medical radiology is a field of medicine that develops the theory and practice of using radiation for medical purposes. It includes two main medical disciplines: diagnostic radiation (diagnostic radiology) and radiation therapy (radiation therapy).

Radiation diagnostics is the science of using radiation to study the structure and functions of normal and pathologically altered human organs and systems for the purpose of preventing and recognizing diseases.

Radiation diagnostics includes x-ray diagnostics, radionuclide diagnostics, ultrasound diagnostics and magnetic resonance imaging. It also includes thermography, microwave thermometry, and magnetic resonance spectrometry. A very important direction in radiation diagnostics is interventional radiology: performing therapeutic interventions under the control of radiation studies.

Today no medical disciplines can do without radiology. Radiation methods are widely used in anatomy, physiology, biochemistry, etc.

Grouping of radiations used in radiology.

All radiation used in medical radiology is divided into two large groups: non-ionizing and ionizing. The former, unlike the latter, when interacting with the environment, do not cause ionization of atoms, i.e., their disintegration into oppositely charged particles - ions. To answer the question about the nature and basic properties of ionizing radiation, we should recall the structure of atoms, since ionizing radiation is intra-atomic (intranuclear) energy.

An atom consists of a nucleus and electron shells. Electron shells are a certain energy level created by electrons rotating around the nucleus. Almost all the energy of an atom lies in its nucleus - it determines the properties of the atom and its weight. The nucleus consists of nucleons - protons and neutrons. The number of protons in an atom is equal to the serial number of a chemical element on the periodic table. The sum of protons and neutrons determines the mass number. Chemical elements located at the beginning of the periodic table have an equal number of protons and neutrons in their nucleus. Such nuclei are stable. The elements at the end of the table have nuclei that are overloaded with neutrons. Such nuclei become unstable and decay over time. This phenomenon is called natural radioactivity. All chemical elements located in the periodic table, starting with No. 84 (polonium), are radioactive.

Radioactivity is understood as a phenomenon in nature when an atom of a chemical element decays, turning into an atom of another element with different chemical properties, and at the same time energy is released into the environment in the form of elementary particles and gamma quanta.

There are colossal forces of mutual attraction between the nucleons in the nucleus. They are characterized by a large magnitude and act at a very short distance, equal to the diameter of the nucleus. These forces are called nuclear forces, which do not obey electrostatic laws. In cases where there is a predominance of some nucleons over others in the nucleus, the nuclear forces become small, the nucleus is unstable, and decays over time.

All elementary particles and gamma quanta have charge, mass and energy. The unit of mass is the mass of a proton, the unit of charge is the charge of an electron.

In turn, elementary particles are divided into charged and uncharged. The energy of elementary particles is expressed in ev, Kev, MeV.

To transform a stable chemical element into a radioactive one, it is necessary to change the proton-neutron equilibrium in the nucleus. To obtain artificially radioactive nucleons (isotopes), three possibilities are usually used:

1. Bombardment of stable isotopes with heavy particles in accelerators (linear accelerators, cyclotrons, synchrophasotrons, etc.).

2. Use of nuclear reactors. In this case, radionuclides are formed as intermediate products of the decay of U-235 (1-131, Cs-137, Sr-90, etc.).

3. Irradiation of stable elements with slow neutrons.

4. Recently, in clinical laboratories, generators have been used to obtain radionuclides (to obtain technetium - molybdenum, indium - charged with tin).

Several types of nuclear transformations are known. The most common are the following:

1. Decay reaction (the resulting substance shifts to the left at the bottom of the cell of the periodic table).

2. Electron decay (where does the electron come from, since it is not in the nucleus? It occurs when a neutron transforms into a proton).

3. Positron decay (in this case, a proton turns into a neutron).

4. Chain reaction - observed during the fission of uranium-235 or plutonium-239 nuclei in the presence of the so-called critical mass. The action of the atomic bomb is based on this principle.

5. Synthesis of light nuclei - thermonuclear reaction. The action of the hydrogen bomb is based on this principle. Fusion of nuclei requires a lot of energy; it is obtained from the explosion of an atomic bomb.

Radioactive substances, both natural and artificial, decay over time. This can be observed by the emanation of radium placed in a sealed glass tube. Gradually the glow of the tube decreases. The decay of radioactive substances follows a certain pattern. The law of radioactive decay states: “The number of decaying atoms of a radioactive substance per unit time is proportional to the number of all atoms,” i.e., a certain part of the atoms always decays per unit time. This is the so-called decay constant (X). It characterizes the relative rate of decay. The absolute decay rate is the number of decays per second. The absolute decay rate characterizes the activity of a radioactive substance.

The unit of radionuclide activity in the SI system of units is the becquerel (Bq): 1 Bq = 1 nuclear transformation in 1 s. In practice, the extra-systemic unit curie (Ci) is also used: 1 Ci = 3.7 * 10 10 nuclear transformations in 1 s (37 billion decays). This is a lot of activity. In medical practice, milli and micro Ki are more often used.

To characterize the rate of decay, a period is used during which the activity is halved (T = 1/2). The half-life is determined in s, minutes, hours, years and millennia. The half-life, for example, of Ts-99t is 6 hours, and the half-life of Ra is 1590 years, and U-235 is 5 billion years. The half-life and decay constant are in a certain mathematical relationship: T = 0.693. Theoretically, complete decay of a radioactive substance does not occur, therefore, in practice, ten half-lives are used, i.e., after this period, the radioactive substance has almost completely decayed. The longest half-life of Bi-209 is 200 thousand billion years, the shortest is

To determine the activity of a radioactive substance, radiometers are used: laboratory, medical, radiographs, scanners, gamma cameras. All of them are built on the same principle and consist of a detector (receiving radiation), an electronic unit (computer) and a recording device that allows you to receive information in the form of curves, numbers or a picture.

Detectors are ionization chambers, gas-discharge and scintillation counters, semiconductor crystals or chemical systems.

The characteristic of its absorption in tissues is of decisive importance for assessing the possible biological effects of radiation. The amount of energy absorbed per unit mass of the irradiated substance is called dose, and the same amount per unit time is called radiation dose rate. The SI unit of absorbed dose is the gray (Gy): 1 Gy = 1 J/kg. The absorbed dose is determined by calculation, using tables, or by introducing miniature sensors into the irradiated tissues and body cavities.

A distinction is made between exposure dose and absorbed dose. Absorbed dose is the amount of radiation energy absorbed in a mass of matter. Exposure dose is the dose measured in air. The unit of exposure dose is the roentgen (milliroentgen, microroentgen). X-ray (g) is the amount of radiant energy absorbed in 1 cm 3 of air under certain conditions (at 0 ° C and normal atmospheric pressure), forming an electric charge equal to 1 or forming 2.08x10 9 pairs of ions.

Dosimetry methods:

1. Biological (erythemal dose, epilation dose, etc.).

2. Chemical (methyl orange, diamond).

3. Photochemical.

4. Physical (ionization, scintillation, etc.).

According to their purpose, dosimeters are divided into the following types:

1. To measure radiation in a direct beam (condenser dosimeter).

2. Control and protection dosimeters (DKZ) - for measuring dose rates in the workplace.

3. Personal control dosimeters.

All these tasks are successfully combined in a thermoluminescent dosimeter (“Telda”). It can measure doses ranging from 10 billion to 10 5 rad, i.e. it can be used both for monitoring protection and for measuring individual doses, as well as doses during radiation therapy. In this case, the dosimeter detector can be mounted in a bracelet, ring, chest badge, etc.

RADIONUCLIDE RESEARCH PRINCIPLES, METHODS, CAPABILITIES

With the advent of artificial radionuclides, tempting prospects opened up for the doctor: by introducing radionuclides into the patient’s body, it is possible to monitor their location using radiometric instruments. In a relatively short period of time, radionuclide diagnostics has become an independent medical discipline.

The radionuclide method is a way to study the functional and morphological state of organs and systems using radionuclides and compounds labeled with them, which are called radiopharmaceuticals. These indicators are introduced into the body, and then using various devices (radiometers) they determine the speed and nature of their movement and removal from organs and tissues. In addition, pieces of tissue, blood, and patient secretions can be used for radiometry. The method is highly sensitive and is carried out in vitro (radioimmunoassay).

Thus, the goal of radionuclide diagnostics is to recognize diseases of various organs and systems using radionuclides and compounds labeled with them. The essence of the method is registration and measurement of radiation from radiopharmaceuticals introduced into the body or radiometry of biological samples using radiometric instruments.

Radionuclides differ from their analogues - stable isotopes - only in their physical properties, that is, they are capable of decaying, producing radiation. The chemical properties are the same, so their introduction into the body does not affect the course of physiological processes.

Currently, 106 chemical elements are known. Of these, 81 have both stable and radioactive isotopes. For the remaining 25 elements, only radioactive isotopes are known. Today, the existence of about 1,700 nuclides has been proven. The number of isotopes of chemical elements ranges from 3 (hydrogen) to 29 (platinum). Of these, 271 nuclides are stable, the rest are radioactive. About 300 radionuclides find or may find practical application in various fields of human activity.

Using radionuclides, you can measure the radioactivity of the body and its parts, study the dynamics of radioactivity, the distribution of radioisotopes, and measure the radioactivity of biological media. Consequently, it is possible to study metabolic processes in the body, the functions of organs and systems, the course of secretory and excretory processes, study the topography of an organ, determine the speed of blood flow, gas exchange, etc.

Radionuclides are widely used not only in medicine, but also in a wide variety of fields of knowledge: archeology and paleontology, metallurgy, agriculture, veterinary medicine, forensic medicine. practice, criminology, etc.

The widespread use of radionuclide methods and their high information content have made radioactive studies an obligatory part of the clinical examination of patients, in particular the brain, kidneys, liver, thyroid gland and other organs.

History of development. As early as 1927, there were attempts to use radium to study the speed of blood flow. However, extensive study of the issue of using radionuclides in widespread practice began in the 40s, when artificial radioactive isotopes were obtained (1934 - Irene and F. Joliot Curie, Frank, Verkhovskaya). P-32 was first used to study metabolism in bone tissue. But until 1950, the introduction of radionuclide diagnostic methods into the clinic was hampered by technical reasons: there were not enough radionuclides, easy-to-use radiometric instruments, or effective research methods. After 1955, research in the field of visualization of internal organs continued intensively in terms of expanding the range of organotropic radiopharmaceuticals and technical re-equipment. The production of a colloidal solution of Au-198.1-131, P-32 was organized. Since 1961, the production of rose bengal-1-131 and hippuran-1-131 began. By 1970, certain traditions had generally developed in the use of specific research techniques (radiometry, radiography, gammatopography, clinical radiometry in vitro. The rapid development of two new techniques began: scintigraphy on cameras and radioimmunological studies in vitro, which today account for 80% of all radionuclide studies in clinic. Currently, the gamma camera can become as widespread as x-ray examination.

Today, a broad program has been outlined to introduce radionuclide research into the practice of medical institutions, which is being successfully implemented. More and more new laboratories are opening, new radiopharmaceuticals and techniques are being introduced. Thus, literally in recent years, tumor-tropic (gallium citrate, labeled bleomycin) and osteotropic radiopharmaceuticals have been created and introduced into clinical practice.

Principles, methods, capabilities

The principles and essence of radionuclide diagnostics are the ability of radionuclides and compounds labeled with them to selectively accumulate in organs and tissues. All radionuclides and radiopharmaceuticals can be divided into 3 groups:

1. Organotropic: a) with directed organotropy (1-131 - thyroid gland, rose bengal-1-131 - liver, etc.); b) with an indirect focus, i.e. temporary concentration in an organ along the path of excretion from the body (urine, saliva, feces, etc.);

2. Tumorotropic: a) specific tumorotropic (gallium citrate, labeled bleomycin); b) nonspecific tumorotropic (1-131 in the study of metastases of thyroid cancer in the bones, rose bengal-1-131 in metastases to the liver, etc.);

3. Determination of tumor markers in blood serum in vitro (alphafetoprotein for liver cancer, carcinoembrysnal antigen - gastrointestinal tumors, choriogonadotropin - chorionepithelioma, etc.).

Advantages of radionuclide diagnostics:

1. Versatility. All organs and systems are subject to the radionuclide diagnostic method;

2. Complexity of research. An example is the study of the thyroid gland (determination of the intrathyroid stage of the iodine cycle, transport-organic, tissue, gammatoporgaphy);

3. Low radiotoxicity (radiation exposure does not exceed the dose received by the patient with one x-ray, and during radioimmunoassay, radiation exposure is completely eliminated, which allows the method to be widely used in pediatric practice;

4. High degree of accuracy of research and the possibility of quantitative recording of the obtained data using a computer.

From the point of view of clinical significance, radionuclide studies are conventionally divided into 4 groups:

1. Fully ensuring the diagnosis (diseases of the thyroid gland, pancreas, metastases of malignant tumors);

2. Determine dysfunction (kidneys, liver);

3. Establish the topographic and anatomical features of the organ (kidneys, liver, thyroid gland, etc.);

4. Obtain additional information in a comprehensive study (lungs, cardiovascular, lymphatic systems).

Requirements for radiopharmaceuticals:

1. Harmlessness (no radiotoxicity). Radiotoxicity should be negligible, which depends on the half-life and half-life (physical and biological half-life). The combination of half-lives and half-lives is the effective half-life. The half-life should be from a few minutes to 30 days. In this regard, radionuclides are divided into: a) long-lived - tens of days (Se-75 - 121 days, Hg-203 - 47 days); b) medium-living - several days (1-131-8 days, Ga-67 - 3.3 days); c) short-lived - several hours (Ts-99t - 6 hours, In-113m - 1.5 hours); d) ultra-short-lived - several minutes (C-11, N-13, O-15 - from 2 to 15 minutes). The latter are used in positron emission tomography (PET).

2. Physiological validity (selectivity of accumulation). However, today, thanks to the achievements of physics, chemistry, biology and technology, it has become possible to include radionuclides in various chemical compounds, the biological properties of which differ sharply from the radionuclide. Thus, technetium can be used in the form of polyphosphate, macro- and microaggregates of albumin, etc.

3. The possibility of recording radiation from a radionuclide, i.e. the energy of gamma quanta and beta particles must be sufficient (from 30 to 140 KeV).

Methods of radionuclide research are divided into: a) research of a living person; b) examination of blood, secretions, excreta and other biological samples.

In vivo methods include:

1. Radiometry (of the whole body or part of it) - determination of the activity of a part of the body or organ. Activity is recorded as numbers. An example is the study of the thyroid gland and its activity.

2. Radiography (gammachronography) - on a radiograph or gamma camera, the dynamics of radioactivity is determined in the form of curves (hepatoradiography, radiorenography).

3. Gammatopography (on a scanner or gamma camera) - the distribution of activity in an organ, which allows one to judge the position, shape, size, and uniformity of drug accumulation.

4. Radioimmune anemia (radiocompetitive) - hormones, enzymes, drugs, etc. are determined in vitro. In this case, the radiopharmaceutical is introduced into a test tube, for example, with the patient’s blood plasma. The method is based on competition between a substance labeled with a radionuclide and its analog in a test tube for complexing (combining) with a specific antibody. An antigen is a biochemical substance that needs to be determined (hormone, enzyme, drug). For analysis you must have: 1) the substance under study (hormone, enzyme); 2) its labeled analogue: the label is usually 1-125 with a half-life of 60 days or tritium with a half-life of 12 years; 3) a specific perceptive system, which is the subject of “competition” between the desired substance and its labeled analogue (antibody); 4) a separation system that separates bound radioactive substances from unbound ones (activated carbon, ion exchange resins, etc.).

Thus, radio competitive analysis consists of 4 main stages:

1. Mixing the sample, labeled antigen and specific receptor system (antibody).

2. Incubation, i.e., the antigen-antibody reaction to equilibrium at a temperature of 4 °C.

3. Separation of free and bound substances using activated carbon, ion exchange resins, etc.

4. Radiometry.

The results are compared with the reference curve (standard). The more of the starting substance (hormone, drug), the less of the labeled analogue will be captured by the binding system and the larger part of it will remain unbound.

Currently, over 400 compounds of various chemical natures have been developed. The method is an order of magnitude more sensitive than laboratory biochemical studies. Today, radioimmunoassay is widely used in endocrinology (diabetes mellitus diagnosis), oncology (search for cancer markers), in cardiology (myocardial infarction diagnosis), in pediatrics (child development disorders), in obstetrics and gynecology (infertility, fetal development disorders ), in allergology, toxicology, etc.

In industrialized countries, the main emphasis is now on organizing positron emission tomography (PET) centers in large cities, which, in addition to a positron emission tomograph, also includes a small-sized cyclotron for the on-site production of positron-emitting ultrashort-lived radionuclides. Where there are no small-sized cyclotrons, the isotope (F-18 with a half-life of about 2 hours) is obtained from their regional radionuclide production centers or generators (Rb-82, Ga-68, Cu-62) are used.

Currently, radionuclide research methods are also used for preventive purposes to identify hidden diseases. Thus, any headache requires a brain study with pertechnetate-Tc-99t. This type of screening allows us to exclude tumors and areas of hemorrhage. A reduced kidney detected in childhood by scintigraphy should be removed to prevent malignant hypertension. A drop of blood taken from the child’s heel allows you to determine the amount of thyroid hormones. If there is a lack of hormones, replacement therapy is carried out, which allows the child to develop normally, keeping up with his peers.

Requirements for radionuclide laboratories:

One laboratory per 200-300 thousand population. It should preferably be placed in therapeutic clinics.

1. It is necessary to place the laboratory in a separate building, built according to a standard design with a security sanitary zone around it. It is forbidden to build children's institutions and catering units on the territory of the latter.

2. The radionuclide laboratory must have a certain set of premises (radiopharmaceutical storage, packaging, generator, washing, treatment room, sanitary inspection room).

3. Special ventilation is provided (five air changes when using radioactive gases), sewerage with a number of settling tanks in which waste of at least ten half-lives is kept.

4. Daily wet cleaning of the premises must be carried out.

METHODS OF RADIATION DIAGNOSTICS

Radiology

METHODS OF RADIATION DIAGNOSTICS
The discovery of X-rays marked the beginning of a new era in medical diagnostics - the era of radiology. Subsequently, the arsenal of diagnostic tools was replenished with methods based on other types of ionizing and non-ionizing radiation (radioisotope, ultrasound methods, magnetic resonance imaging). Year after year, radiation research methods have been improved. Currently, they play a leading role in identifying and establishing the nature of most diseases.
At this stage of study, you have a (general) goal: to be able to interpret the principles of obtaining a medical diagnostic image using various radiation methods and the purpose of these methods.
Achieving a common goal is ensured by specific goals:
be able to:
1) interpret the principles of obtaining information using x-ray, radioisotope, ultrasound research methods and magnetic resonance imaging;
2) interpret the purpose of these research methods;
3) interpret the general principles of choosing the optimal radiation research method.
It is impossible to master the above goals without basic knowledge and skills taught at the Department of Medical and Biological Physics:
1) interpret the principles of production and physical characteristics of x-rays;
2) interpret radioactivity, the resulting radiation and their physical characteristics;
3) interpret the principles of producing ultrasonic waves and their physical characteristics;
5) interpret the phenomenon of magnetic resonance;
6) interpret the mechanism of biological action of various types of radiation.

1. X-ray research methods
X-ray examination still plays an important role in the diagnosis of human diseases. It is based on the varying degrees of absorption of X-rays by various tissues and organs of the human body. The rays are absorbed to a greater extent in the bones, to a lesser extent - in parenchymal organs, muscles and body fluids, even less - in fatty tissue and are almost not retained in gases. In cases where nearby organs equally absorb x-rays, they are not distinguishable during x-ray examination. In such situations, artificial contrast is resorted to. Consequently, X-ray examination can be carried out under conditions of natural contrast or artificial contrast. There are many different x-ray examination techniques.
The (general) goal of studying this section is to be able to interpret the principles of obtaining x-ray images and the purpose of various x-ray examination methods.
1) interpret the principles of image acquisition using fluoroscopy, radiography, tomography, fluorography, contrast research techniques, computed tomography;
2) interpret the purpose of fluoroscopy, radiography, tomography, fluorography, contrast research techniques, computed tomography.
1.1. X-ray
Fluoroscopy, i.e. obtaining a shadow image on a translucent (fluorescent) screen is the most accessible and technically simple research technique. It allows us to judge the shape, position and size of the organ and, in some cases, its function. By examining the patient in various projections and body positions, the radiologist obtains a three-dimensional understanding of the human organs and the identified pathology. The more radiation is absorbed by the organ or pathological formation being examined, the fewer rays hit the screen. Therefore, such an organ or formation casts a shadow on the fluorescent screen. And vice versa, if an organ or pathology is less dense, then more rays pass through them, and they hit the screen, causing it to become clear (glow).
The fluorescent screen glows faintly. Therefore, this study is carried out in a darkened room, and the doctor must adapt to the dark within 15 minutes. Modern X-ray machines are equipped with electron-optical converters that amplify and transmit the X-ray image to a monitor (TV screen).
However, fluoroscopy has significant disadvantages. Firstly, it causes significant radiation exposure. Secondly, its resolution is much lower than radiography.
These disadvantages are less pronounced when using X-ray television scanning. On the monitor you can change the brightness and contrast, thereby creating better viewing conditions. The resolution of such fluoroscopy is much higher, and the radiation exposure is less.
However, any screening is subjectivity. All physicians must rely on the expertise of the radiologist. In some cases, to objectify the study, the radiologist takes radiographs during the copy. For the same purpose, a video recording of the study using X-ray television scanning is also carried out.
1.2. Radiography
Radiography is a method of x-ray examination in which an image is obtained on x-ray film. The radiograph is a negative in relation to the image visible on the fluoroscopic screen. Therefore, light areas on the screen correspond to dark areas on the film (so-called highlights), and vice versa, dark areas correspond to light areas (shadows). Radiographs always produce a planar image with the summation of all points located along the ray path. To obtain a three-dimensional representation, it is necessary to take at least 2 photographs in mutually perpendicular planes. The main advantage of radiography is the ability to document detectable changes. In addition, it has significantly greater resolution than fluoroscopy.
In recent years, digital radiography has found application, in which special plates serve as X-ray receivers. After exposure to X-rays, a latent image of the object remains on them. When scanning plates with a laser beam, energy is released in the form of a glow, the intensity of which is proportional to the dose of absorbed x-ray radiation. This glow is recorded by a photodetector and converted into digital format. The resulting image can be displayed on a monitor, printed on a printer and stored in the computer's memory.
1.3. Tomography
Tomography is an x-ray method for layer-by-layer examination of organs and tissues. On tomograms, in contrast to x-rays, images of structures located in any one plane are obtained, i.e. the summation effect is eliminated. This is achieved through the simultaneous movement of the X-ray tube and film. The advent of computed tomography has sharply reduced the use of tomography.
1.4. Fluorography
Fluorography is usually used to conduct mass screening X-ray examinations, especially to detect lung pathology. The essence of the method is to photograph an image from an X-ray screen or an electron-optical amplifier screen onto photographic film. The frame size is usually 70x70 or 100x100 mm. On fluorograms, image details are visible better than with fluoroscopy, but worse than with radiography. The radiation dose received by the subject is also greater than with radiography.
1.5. Methods of X-ray examination under artificial contrast conditions
As mentioned above, a number of organs, especially hollow ones, absorb X-rays almost equally with the surrounding soft tissues. Therefore, they are not detected during X-ray examination. For visualization, they are artificially contrasted by injecting a contrast agent. Most often, various liquid iodide compounds are used for this purpose.
In some cases, it is important to obtain an image of the bronchi, especially in cases of bronchiectasis, congenital bronchial defects, or the presence of an internal bronchial or bronchopleural fistula. In such cases, a study using contrasting bronchial tubes - bronchography - helps to establish a diagnosis.
Blood vessels are not visible on conventional x-rays, with the exception of the pulmonary vessels. To assess their condition, angiography is performed - an X-ray examination of blood vessels using a contrast agent. During arteriography, a contrast agent is injected into the arteries, and during venography, into the veins.
When a contrast agent is injected into an artery, the image normally shows the phases of blood flow sequentially: arterial, capillary and venous.
Contrast studies are of particular importance when studying the urinary system.
There are excretory (excretory) urography and retrograde (ascending) pyelography. Excretory urography is based on the physiological ability of the kidneys to capture iodinated organic compounds from the blood, concentrate them and excrete them in the urine. Before the study, the patient needs appropriate preparation - bowel cleansing. The study is carried out on an empty stomach. Usually 20-40 ml of one of the urotropic substances is injected into the cubital vein. Then, after 3-5, 10-14 and 20-25 minutes, pictures are taken. If the secretory function of the kidneys is reduced, infusion urography is performed. In this case, the patient is slowly injected with a large amount of contrast agent (60–100 ml), diluted with a 5% glucose solution.
Excretory urography makes it possible to evaluate not only the pelvis, calyces, ureters, general shape and size of the kidneys, but also their functional state.
In most cases, excretory urography provides sufficient information about the renal-pelvic system. But still, in isolated cases, when this fails for some reason (for example, with a significant decrease or absence of kidney function), ascending (retrograde) pyelography is performed. To do this, a catheter is inserted into the ureter to the desired level, right up to the pelvis, a contrast agent (7-10 ml) is injected through it and pictures are taken.
To study the biliary tract, percutaneous transhepatic cholegraphy and intravenous cholecystocholangiography are currently used. In the first case, the contrast agent is injected through a catheter directly into the common bile duct. In the second case, the contrast administered intravenously in hepatocytes mixes with bile and is excreted with it, filling the bile ducts and gallbladder.
To assess the patency of the fallopian tubes, hysterosalpingography (metroslpingography) is used, in which a contrast agent is injected through the vagina into the uterine cavity using a special syringe.
A contrast X-ray technique for studying the ducts of various glands (mammary, salivary, etc.) is called ductography, and various fistulous tracts are called fistulography.
The digestive tract is studied under artificial contrast conditions using a suspension of barium sulfate, which the patient takes orally when examining the esophagus, stomach and small intestine, and is administered retrogradely when examining the colon. Assessment of the condition of the digestive tract is necessarily carried out by fluoroscopy with a series of radiographs. The study of the colon has a special name - irrigoscopy with irrigography.
1.6. CT scan
Computed tomography (CT) is a method of layer-by-layer X-ray examination, which is based on computer processing of multiple X-ray images of layers of the human body in cross section. Around the human body, multiple ionization or scintillation sensors are located around the circumference, capturing X-ray radiation that has passed through the subject.
Using a computer, the doctor can enlarge the image, highlight and enlarge its various parts, determine the dimensions and, what is very important, estimate the density of each area in conventional units. Information about tissue density can be presented in the form of numbers and histograms. To measure density, the Hounswild scale with a range of over 4000 units is used. The density of water is taken as the zero density level. The density of bones ranges from +800 to +3000 H units (Hounswild), parenchymal tissue - within 40-80 H units, air and gases - about -1000 H units.
Dense formations on CT are visible lighter and are called hyperdense, less dense formations are visible lighter and are called hypodense.
Contrast agents are also used to enhance contrast in CT scans. Intravenously administered iodide compounds improve the visualization of pathological foci in parenchymal organs.
An important advantage of modern computed tomographs is the ability to reconstruct a three-dimensional image of an object using a series of two-dimensional images.
2. Radionuclide research methods
The possibility of obtaining artificial radioactive isotopes has made it possible to expand the scope of application of radioactive tracers in various branches of science, including medicine. Radionuclide imaging is based on recording the radiation emitted by a radioactive substance inside the patient. Thus, what is common between X-ray and radionuclide diagnostics is the use of ionizing radiation.
Radioactive substances, called radiopharmaceuticals (RPs), can be used for both diagnostic and therapeutic purposes. All of them contain radionuclides - unstable atoms that spontaneously decay with the release of energy. An ideal radiopharmaceutical accumulates only in organs and structures targeted for imaging. The accumulation of radiopharmaceuticals can be caused, for example, by metabolic processes (the carrier molecule may be part of a metabolic chain) or by local perfusion of the organ. The ability to study physiological functions in parallel with the determination of topographic and anatomical parameters is the main advantage of radionuclide diagnostic methods.
For imaging, radionuclides that emit gamma rays are used, since alpha and beta particles have low tissue penetration.
Depending on the degree of radiopharmaceutical accumulation, a distinction is made between “hot” foci (with increased accumulation) and “cold” foci (with reduced or no accumulation).
There are several different methods for radionuclide testing.
The (general) goal of studying this section is to be able to interpret the principles of obtaining radionuclide images and the purpose of various radionuclide research methods.
To do this you need to be able to:
1) interpret the principles of image acquisition during scintigraphy, emission computed tomography (single-photon and positron);
2) interpret the principles of obtaining radiographic curves;
2) interpret the purpose of scintigraphy, emission computed tomography, radiography.
Scintigraphy is the most common radionuclide imaging method. The study is carried out using a gamma camera. Its main component is a disc-shaped scintillation crystal of sodium iodide of large diameter (about 60 cm). This crystal is a detector that captures the gamma radiation emitted by the radiopharmaceutical. In front of the crystal on the patient's side there is a special lead protective device - a collimator, which determines the projection of radiation onto the crystal. Parallel holes on the collimator facilitate the projection of a two-dimensional display of the radiopharmaceutical distribution on a 1:1 scale onto the crystal surface.
Gamma photons hitting a scintillation crystal cause flashes of light (scintillation) on it, which are transmitted to a photomultiplier tube, which generates electrical signals. Based on the registration of these signals, a two-dimensional projection image of the radiopharmaceutical distribution is reconstructed. The final image can be presented in analogue format on photographic film. However, most gamma cameras can also create digital images.
Most scintigraphic studies are performed after intravenous administration of a radiopharmaceutical (the exception is inhalation of radioactive xenon during inhalation lung scintigraphy).
Lung perfusion scintigraphy uses 99mTc-labeled albumin macroaggregates or microspheres, which are retained in the smallest pulmonary arterioles. Images are obtained in direct (anterior and posterior), lateral and oblique projections.
Skeletal scintigraphy is performed using Tc99m-labeled diphosphonates that accumulate in metabolically active bone tissue.
Hepatobiliscintigraphy and hepatoscintigraphy are used to study the liver. The first method studies the biliary and biliary function of the liver and the condition of the biliary tract - their patency, storage and contractility of the gallbladder, and is a dynamic scintigraphic study. It is based on the ability of hepatocytes to absorb certain organic substances from the blood and transport them in the bile.
Hepatoscintigraphy - static scintigraphy - allows you to assess the barrier function of the liver and spleen and is based on the fact that stellate reticulocytes of the liver and spleen, purifying the plasma, phagocytose particles of the radiopharmaceutical colloid solution.
To study the kidneys, static and dynamic nephroscintigraphy is used. The essence of the method is to obtain an image of the kidneys by fixing nephrotropic radiopharmaceuticals in them.
2.2. Emission computed tomography
Single photon emission computed tomography (SPECT) is especially widely used in cardiology and neurology practice. The method is based on rotating a conventional gamma camera around the patient's body. Registration of radiation at various points of the circle allows one to reconstruct a sectional image.
Positron emission tomography (PET), unlike other radionuclide examination methods, is based on the use of positrons emitted by radionuclides. Positrons, having the same mass as electrons, are positively charged. The emitted positron immediately interacts with a nearby electron (a reaction called annihilation), resulting in two gamma-ray photons traveling in opposite directions. These photons are recorded by special detectors. The information is then transferred to a computer and converted into a digital image.
PET makes it possible to quantify the concentration of radionuclides and thereby study metabolic processes in tissues.
2.3. Radiography
Radiography is a method of assessing the function of an organ through external graphic recording of changes in radioactivity above it. Currently, this method is used mainly to study the condition of the kidneys - radiorenography. Two scintigraphic detectors record radiation over the right and left kidneys, the third – over the heart. A qualitative and quantitative analysis of the obtained renograms is carried out.
3. Ultrasound research methods
Ultrasound refers to sound waves with a frequency above 20,000 Hz, i.e. above the hearing threshold of the human ear. Ultrasound is used in diagnostics to obtain sectional images (slices) and measure the speed of blood flow. The most commonly used frequencies in radiology are in the range of 2-10 MHz (1 MHz = 1 million Hz). The ultrasound imaging technique is called sonography. The technology for measuring blood flow velocity is called Dopplerography.
The (general) goal of studying this section is to learn to interpret the principles of obtaining ultrasound images and the purpose of various ultrasound research methods.
To do this you need to be able to:
1) interpret the principles of obtaining information during sonography and Dopplerography;
2) interpret the purpose of sonography and Dopplerography.
3.1. Sonography
Sonography is carried out by passing a narrowly directed ultrasound beam through the patient's body. Ultrasound is generated by a special transducer, usually placed on the patient's skin over the anatomical area being examined. The sensor contains one or more piezoelectric crystals. Applying an electric potential to a crystal leads to its mechanical deformation, and mechanical compression of the crystal generates an electric potential (inverse and direct piezoelectric effect). Mechanical vibrations of the crystal generate ultrasound, which is reflected from various tissues and returns back to the transducer as an echo, generating mechanical vibrations of the crystal and therefore electrical signals of the same frequency as the echo. This is how the echo is recorded.
The intensity of the ultrasound gradually decreases as it passes through the patient's body tissue. The main reason for this is the absorption of ultrasound in the form of heat.
The unabsorbed portion of the ultrasound may be scattered or reflected back to the transducer by tissue as an echo. The ease with which ultrasound can pass through tissue depends partly on the mass of the particles (which determines the density of the tissue) and partly on the elastic forces that attract the particles to each other. The density and elasticity of a fabric together determine its so-called acoustic resistance.
The greater the change in acoustic impedance, the greater the reflection of ultrasound. A large difference in acoustic impedance exists at the soft tissue-gas interface, and almost all ultrasound is reflected from it. Therefore, a special gel is used to eliminate air between the patient's skin and the sensor. For the same reason, sonography does not allow visualization of the areas located behind the intestines (since the intestines are filled with gas) and the lung tissue containing air. There is also a relatively large difference in acoustic impedance between soft tissue and bone. Most bony structures thus preclude sonography.
The simplest way to display the recorded echo is the so-called A-mode (amplitude mode). In this format, echoes from different depths are represented as vertical peaks on a horizontal depth line. The strength of the echo determines the height or amplitude of each of the peaks shown. The A-mode format provides only a one-dimensional image of changes in acoustic impedance along the line of passage of the ultrasound beam and is used extremely limitedly in diagnostics (currently only for examining the eyeball).
An alternative to A-mode is M-mode (M - motion, movement). In this image, the depth axis on the monitor is oriented vertically. Various echoes are reflected as dots, the brightness of which is determined by the strength of the echo. These bright dots move across the screen from left to right, thereby creating bright curves that show the changing position of reflective structures over time. M-mode curves provide detailed information about the dynamic behavior of reflective structures located along the ultrasound beam. This method is used to obtain dynamic one-dimensional images of the heart (chamber walls and heart valve leaflets).
The most widely used mode in radiology is B-mode (B - brightness). This term means that the echo is depicted on the screen in the form of dots, the brightness of which is determined by the strength of the echo. B-mode provides a two-dimensional sectional anatomical image (slice) in real time. Images are created on the screen in the form of a rectangle or sector. The images are dynamic and can show phenomena such as respiratory movements, vascular pulsations, heartbeats and fetal movements. Modern ultrasound machines use digital technology. The analog electrical signal generated in the sensor is digitized. The final image on the monitor is represented by shades of gray scale. Lighter areas are called hyperechoic, darker areas are called hypo- and anechoic.
3.2. Dopplerography
Measuring blood flow velocity using ultrasound is based on the physical phenomenon that the frequency of sound reflected from a moving object changes compared to the frequency of the sent sound when received by a stationary receiver (Doppler effect).
During Doppler examination of blood vessels, an ultrasound beam generated by a special Doppler sensor is passed through the body. When this beam crosses a vessel or cardiac chamber, a small part of the ultrasound is reflected from red blood cells. The frequency of the echo waves reflected from these cells moving towards the sensor will be higher than the waves emitted by the sensor itself. The difference between the frequency of the received echo and the frequency of the ultrasound generated by the transducer is called the Doppler frequency shift, or Doppler frequency. This frequency shift is directly proportional to the speed of blood flow. When measuring flow, the frequency shift is continuously measured by the instrument; Most such systems automatically convert the change in ultrasound frequency into relative blood flow velocity (for example, in m/s), using which the true blood flow velocity can be calculated.
The Doppler frequency shift usually lies within the frequency range audible to the human ear. Therefore, all Doppler equipment is equipped with speakers that allow you to hear the Doppler frequency shift. This "flow sound" is used both to detect vessels and to semi-quantitatively assess the nature of blood flow and its speed. However, such a sound display is of little use for accurate speed estimation. In this regard, a Doppler study provides a visual display of flow velocity - usually in the form of graphs or in the form of waves, where the ordinate is velocity and the abscissa is time. In cases where the blood flow is directed towards the sensor, the Dopplerogram graph is located above the isoline. If the blood flow is directed away from the sensor, the graph is located below the isoline.
There are two fundamentally different options for emitting and receiving ultrasound when using the Doppler effect: constant wave and pulsed. In continuous wave mode, the Doppler sensor uses two separate crystals. One crystal continuously emits ultrasound, while the other receives echoes, allowing very high speeds to be measured. Since velocities are simultaneously measured over a large range of depths, it is not possible to selectively measure velocities at a specific, predetermined depth.
In pulsed mode, the same crystal emits and receives ultrasound. Ultrasound is emitted in short pulses and echoes are recorded during the waiting periods between pulse transmissions. The time interval between the transmission of the pulse and the reception of the echo determines the depth at which velocities are measured. Pulsed Doppler can measure flow velocities in very small volumes (called control volumes) located along the ultrasound beam, but the highest velocities available for measurement are significantly lower than those that can be measured using continuous wave Doppler.
Currently, radiology uses so-called duplex scanners, which combine sonography and pulsed Dopplerography. With duplex scanning, the direction of the Doppler beam is superimposed on the B-mode image, and thus it is possible, using electronic markers, to select the size and location of the control volume along the direction of the beam. By moving the electronic cursor parallel to the direction of blood flow, the Doppler shift is automatically measured and the true flow velocity is displayed.
Color visualization of blood flow is a further development of duplex scanning. Colors are superimposed on the B-mode image to show the presence of moving blood. Fixed tissues are displayed in shades of a gray scale, and vessels are displayed in color (shades of blue, red, yellow, green, determined by the relative speed and direction of blood flow). The color image gives an idea of ​​the presence of various vessels and blood flows, but the quantitative information provided by this method is less accurate than with continuous wave or pulsed Doppler studies. Therefore, color visualization of blood flow is always combined with pulsed Doppler ultrasound.
4. Magnetic resonance research methods
The (general) goal of studying this section is to learn to interpret the principles of obtaining information from magnetic resonance research methods and interpret their purpose.
To do this you need to be able to:
1) interpret the principles of obtaining information from magnetic resonance imaging and magnetic resonance spectroscopy;
2) interpret the purpose of magnetic resonance imaging and magnetic resonance spectroscopy.
4.1. Magnetic resonance imaging
Magnetic resonance imaging (MRI) is the “youngest” of radiological methods. Magnetic resonance imaging scanners allow you to create cross-sectional images of any part of the body in three planes.
The main components of an MRI scanner are a strong magnet, a radio transmitter, a radio frequency receiving coil, and a computer. The inside of the magnet is a cylindrical tunnel large enough to fit an adult inside.
MR imaging uses magnetic fields ranging from 0.02 to 3 Tesla (tesla). Most MRI scanners have a magnetic field oriented parallel to the long axis of the patient's body.
When a patient is placed inside a magnetic field, all the hydrogen nuclei (protons) in his body turn in the direction of this field (like a compass needle aligned with the Earth's magnetic field). In addition, the magnetic axes of each proton begin to rotate around the direction of the external magnetic field. This rotational motion is called precession, and its frequency is called the resonant frequency.
Most protons are oriented parallel to the external magnetic field of the magnet ("parallel protons"). The rest precess antiparallel to the external magnetic field (“antiparallel protons”). As a result, the patient's tissues are magnetized and their magnetism is oriented exactly parallel to the external magnetic field. The amount of magnetism is determined by the excess of parallel protons. The excess is proportional to the strength of the external magnetic field, but it is always extremely small (on the order of 1-10 protons per 1 million). Magnetism is also proportional to the number of protons per unit volume of tissue, i.e. proton density. The huge number (about 1022 per ml of water) of hydrogen nuclei contained in most tissues provides magnetism sufficient to induce an electric current in the receiving coil. But a prerequisite for inducing current in the coil is a change in the strength of the magnetic field. This requires radio waves. When short electromagnetic radio frequency pulses are passed through the patient's body, the magnetic moments of all protons rotate by 90º, but only if the frequency of the radio waves is equal to the resonant frequency of the protons. This phenomenon is called magnetic resonance (resonance - synchronous oscillations).
The sensing coil is located outside the patient. The magnetism of the tissue induces an electrical current in the coil, and this current is called the MR signal. Tissues with large magnetic vectors induce strong signals and appear bright - hyperintense on the image, while tissues with small magnetic vectors induce weak signals and appear dark - hypointense on the image.
As stated earlier, contrast in MR images is determined by differences in the magnetic properties of tissues. The magnitude of the magnetic vector is primarily determined by the proton density. Objects with a small number of protons, such as air, induce a very weak MR signal and appear dark in the image. Water and other liquids should appear on MR images as having a very high proton density. However, depending on the mode used to obtain the MR image, fluids can produce either bright or dark images. The reason for this is that the contrast of the image is determined not only by the proton density. Other parameters also play a role; the two most important of them are T1 and T2.
Several MR signals are needed to reconstruct an image, i.e. Several radiofrequency pulses must be transmitted through the patient's body. In the interval between the application of pulses, the protons undergo two different relaxation processes - T1 and T2. The rapid attenuation of the induced signal is partly a result of T2 relaxation. Relaxation is a consequence of the gradual disappearance of magnetization. Liquids and fluid-like tissues typically have long T2 times, while solid tissues and substances typically have short T2 times. The longer T2, the brighter (lighter) the fabric looks, i.e. gives a more intense signal. MR images in which contrast is predominantly determined by differences in T2 are called T2-weighted images.
T1 relaxation is a slower process compared to T2 relaxation, which consists in the gradual alignment of individual protons along the direction of the magnetic field. In this way, the state preceding the radiofrequency pulse is restored. The T1 value largely depends on the size of the molecules and their mobility. As a rule, T1 is minimal for tissues with molecules of medium size and average mobility, for example, adipose tissue. Smaller, more mobile molecules (as in liquids) and larger, less mobile molecules (as in solids) have a higher T1 value.
Tissues with minimal T1 will induce the strongest MR signals (eg, adipose tissue). This way, these fabrics will be bright in the image. Tissues with maximum T1 will accordingly induce the weakest signals and will be dark. MR images in which contrast is predominantly determined by differences in T1 are called T1-weighted images.
Differences in the strength of MR signals obtained from different tissues immediately after exposure to a radiofrequency pulse reflect differences in proton density. In proton density-weighted images, tissues with the highest proton density induce the strongest MR signal and appear brightest.
Thus, in MRI there is much more opportunity to change the contrast of images than in alternative techniques such as computed tomography and sonography.
As mentioned, RF pulses only induce MR signals if the pulse frequency exactly matches the resonant frequency of the protons. This fact makes it possible to obtain MR signals from a pre-selected thin layer of tissue. Special coils create small additional fields so that the strength of the magnetic field increases linearly in one direction. The resonant frequency of protons is proportional to the strength of the magnetic field, so it will also increase linearly in the same direction. By delivering radiofrequency pulses with a predetermined narrow frequency range, it is possible to record MR signals only from a thin layer of tissue, the range of resonant frequencies of which corresponds to the frequency range of the radio pulses.
In MR imaging, the signal intensity of static blood is determined by the selected “weighting” of the image (in practice, static blood is in most cases visualized as bright). In contrast, circulating blood practically does not generate an MR signal, thus being an effective “negative” contrast agent. The lumens of blood vessels and chambers of the heart appear dark and are clearly demarcated from the brighter stationary tissues surrounding them.
There are, however, special MRI techniques that make it possible to display circulating blood as bright and stationary tissue as dark. They are used in MR angiography (MRA).
Contrast agents are widely used in MRI. All of them have magnetic properties and change the intensity of the image of the tissues in which they are located, shortening the relaxation (T1 and/or T2) of the protons surrounding them. The most commonly used contrast agents contain the paramagnetic metal ion gadolinium (Gd3+) bound to a carrier molecule. These contrast agents are administered intravenously and are distributed throughout the body similar to water-soluble X-ray contrast agents.
4.2. Magnetic resonance spectroscopy
An MR unit with a magnetic field strength of at least 1.5 Tesla allows for magnetic resonance spectroscopy (MRS) in vivo. MRS is based on the fact that atomic nuclei and molecules in a magnetic field cause local changes in the strength of the field. The nuclei of atoms of the same type (for example, hydrogen) have resonant frequencies that vary slightly depending on the molecular arrangement of the nuclei. The MR signal induced after exposure to a radiofrequency pulse will contain these frequencies. As a result of frequency analysis of a complex MR signal, a frequency spectrum is created, i.e. amplitude-frequency characteristic showing the frequencies present in it and the corresponding amplitudes. Such a frequency spectrum can provide information about the presence and relative concentrations of different molecules.
Several types of nuclei can be used in MRS, but the two most frequently studied are hydrogen (1H) and phosphorus (31P) nuclei. A combination of MR imaging and MR spectroscopy is possible. In vivo MRS allows one to obtain information about important metabolic processes in tissues, but this method is still far from routine use in clinical practice.

5. General principles for choosing the optimal radiation research method
The purpose of studying this section corresponds to its name - to learn to interpret the general principles of choosing the optimal radiation research method.
As shown in the previous sections, there are four groups of radiation research methods - x-ray, ultrasound, radionuclide and magnetic resonance. To effectively use them in diagnosing various diseases, a physician must be able to choose from this variety of methods the optimal one for a specific clinical situation. In this case, one should be guided by the following criteria:
1) informativeness of the method;
2) the biological effect of radiation used in this method;
3) accessibility and cost-effectiveness of the method.

Information content of radiation research methods, i.e. their ability to provide the doctor with information about the morphological and functional state of various organs is the main criterion for choosing the optimal radiation research method and will be covered in detail in the sections of the second part of our textbook.
Information about the biological effect of radiation used in one or another radiation research method refers to the initial level of knowledge and skills mastered in the course of medical and biological physics. However, given the importance of this criterion when prescribing a radiation method to a patient, it should be emphasized that all x-ray and radionuclide methods are associated with ionizing radiation and, accordingly, cause ionization in the tissues of the patient’s body. If these methods are carried out correctly and the principles of radiation safety are observed, they do not pose a threat to human health and life, because all changes caused by them are reversible. At the same time, their unreasonably frequent use can lead to an increase in the total radiation dose received by the patient, an increase in the risk of tumors and the development of local and general radiation reactions in his body, which you will learn about in detail from the courses of radiation therapy and radiation hygiene.
The main biological effect of ultrasound and magnetic resonance imaging is heating. This effect is more pronounced with MRI. Therefore, the first three months of pregnancy are regarded by some authors as an absolute contraindication for MRI due to the risk of fetal overheating. Another absolute contraindication to the use of this method is the presence of a ferromagnetic object, the movement of which can be dangerous for the patient. The most important are intracranial ferromagnetic clips on blood vessels and intraocular ferromagnetic foreign bodies. The greatest potential danger associated with them is bleeding. The presence of pacemakers is also an absolute contraindication for MRI. The functioning of these devices may be affected by the magnetic field and, furthermore, electrical currents may be induced in their electrodes that can heat the endocardium.
The third criterion for choosing the optimal research method - accessibility and cost-effectiveness - is less important than the first two. However, when referring a patient for examination, any doctor should remember that he should start with more accessible, common and less expensive methods. Compliance with this principle is, first of all, in the interests of the patient, who will be diagnosed in a shorter time.
Thus, when choosing the optimal radiation research method, the doctor should mainly be guided by its information content, and from several methods that are similar in information content, prescribe the one that is more accessible and has less impact on the patient’s body.

Created 21 Dec 2006

*Preventive examination (fluorography is performed once a year to exclude the most dangerous lung pathology) *Indications for use

*Metabolic and endocrine diseases (osteoporosis, gout, diabetes mellitus, hyperthyroidism, etc.) *Indications for use

*Kidney diseases (pyelonephritis, urolithiasis, etc.), in which case radiography is performed with contrast Right-sided acute pyelonephritis *Indications for use

*Diseases of the gastrointestinal tract (intestinal diverticulosis, tumors, strictures, hiatal hernia, etc.). *Indications for use

*Pregnancy – there is a possibility of negative effects of radiation on the development of the fetus. *Bleeding, open wounds. Due to the fact that the vessels and cells of the red bone marrow are very sensitive to radiation, the patient may experience disturbances in blood flow in the body. *General serious condition of the patient, so as not to aggravate the patient’s condition. *Contraindications for use

*Age. X-rays are not recommended for children under 14 years of age, as the human body is too exposed to X-rays before puberty. *Obesity. It is not a contraindication, but excess weight complicates the diagnostic process. *Contraindications for use

* In 1880, French physicists, brothers Pierre and Paul Curie, noticed that when a quartz crystal is compressed and stretched on both sides, electric charges appear on its faces perpendicular to the direction of compression. This phenomenon was called piezoelectricity. Langevin tried to charge the faces of a quartz crystal with electricity from a high-frequency alternating current generator. At the same time, he noticed that the crystal oscillated in time with the change in voltage. To enhance these vibrations, the scientist placed not one, but several plates between steel electrode sheets and achieved resonance - a sharp increase in the amplitude of vibrations. These Langevin studies made it possible to create ultrasonic emitters of various frequencies. Later, emitters based on barium titanate, as well as other crystals and ceramics, which can be of any shape and size, appeared.

* ULTRASONIC RESEARCH Ultrasound diagnostics is currently widespread. Basically, when recognizing pathological changes in organs and tissues, ultrasound with a frequency of 500 kHz to 15 MHz is used. Sound waves of this frequency have the ability to pass through the tissues of the body, reflecting from all surfaces lying on the border of tissues of different composition and density. The received signal is processed by an electronic device, the result is produced in the form of a curve (echogram) or a two-dimensional image (the so-called sonogram - ultrasound scanogram).

* The safety issues of ultrasound examinations are studied at the level of the International Association of Ultrasound Diagnostics in Obstetrics and Gynecology. Today it is generally accepted that ultrasound does not have any negative effects. * The use of ultrasound diagnostic method is painless and practically harmless, as it does not cause tissue reactions. Therefore, there are no contraindications for ultrasound examination. Due to its harmlessness and simplicity, the ultrasound method has all the advantages when examining children and pregnant women. * Is ultrasound harmful?

*ULTRASOUND TREATMENT Currently, treatment with ultrasonic vibrations has become very widespread. Ultrasound with a frequency of 22 – 44 kHz and from 800 kHz to 3 MHz is mainly used. The depth of penetration of ultrasound into tissue during ultrasound therapy is from 20 to 50 mm, while ultrasound has a mechanical, thermal, physico-chemical effect, under its influence metabolic processes and immune reactions are activated. Ultrasound characteristics used in therapy have a pronounced analgesic, antispasmodic, anti-inflammatory, antiallergic and general tonic effect, it stimulates blood and lymph circulation, as already mentioned, regeneration processes; improves tissue trophism. Thanks to this, ultrasound therapy has found wide application in the clinic of internal diseases, arthrology, dermatology, otolaryngology, etc.

Ultrasound procedures are dosed according to the intensity of the ultrasound used and the duration of the procedure. Usually low ultrasound intensities are used (0.05 - 0.4 W/cm2), less often medium (0.5 - 0.8 W/cm2). Ultrasound therapy can be carried out in continuous and pulsed ultrasonic vibration modes. Continuous mode of exposure is more often used. In pulsed mode, the thermal effect and overall ultrasound intensity are reduced. The pulse mode is recommended for the treatment of acute diseases, as well as for ultrasound therapy in children and elderly people with concomitant diseases of the cardiovascular system. Ultrasound affects only a limited part of the body with an area of ​​100 to 250 cm 2, these are reflexogenic zones or the affected area.

Intracellular fluids change electrical conductivity and acidity, and the permeability of cell membranes changes. Ultrasound treatment of blood gives some insight into these events. After such treatment, the blood acquires new properties - the body’s defenses are activated, its resistance to infections, radiation, and even stress increases. Experiments on animals show that ultrasound does not have a mutagenic or carcinogenic effect on cells - its exposure time and intensity are so insignificant that such a risk is practically reduced to zero. And, nevertheless, doctors, based on many years of experience in using ultrasound, have established some contraindications for ultrasound therapy. These are acute intoxications, blood diseases, coronary heart disease with angina pectoris, thrombophlebitis, tendency to bleeding, low blood pressure, organic diseases of the Central Nervous System, severe neurotic and endocrine disorders. After many years of discussions, it was accepted that ultrasound treatment is also not recommended during pregnancy.

*Over the past 10 years, a huge number of new drugs produced in the form of aerosols have appeared. They are often used for respiratory diseases, chronic allergies, and for vaccination. Aerosol particles ranging in size from 0.03 to 10 microns are used for inhalation of the bronchi and lungs, and for treating premises. They are obtained using ultrasound. If such aerosol particles are charged in an electric field, then even more uniformly scattering (so-called highly dispersed) aerosols appear. By treating medicinal solutions with ultrasound, emulsions and suspensions are obtained that do not separate for a long time and retain their pharmacological properties. *Ultrasound to help pharmacologists.

*Transportation of liposomes, fatty microcapsules filled with drugs, into tissues pre-treated with ultrasound also turned out to be very promising. In tissues heated by ultrasound to 42 - 45 * C, the liposomes themselves are destroyed, and the drug enters the cells through membranes that have become permeable under the influence of ultrasound. Liposomal transport is extremely important in the treatment of some acute inflammatory diseases, as well as in tumor chemotherapy, since drugs are concentrated only in a certain area, with little effect on other tissues. *Ultrasound to help pharmacologists.

*Contrast radiography is a whole group of X-ray examination methods, the distinctive feature of which is the use of radiopaque agents during the study to increase the diagnostic value of the images. Most often, contrast is used to study hollow organs, when it is necessary to evaluate their location and volume, the structural features of their walls, and functional characteristics.

These methods are widely used in X-ray examination of the gastrointestinal tract, organs of the urinary system (urography), assessment of the localization and extent of fistulous tracts (fistulography), structural features of the vascular system and the efficiency of blood flow (angiography), etc.

*Contrast can be invasive, when a contrast agent is introduced into the body cavity (intramuscular, intravenous, intra-arterial) with damage to the skin, mucous membranes, or non-invasive, when the contrast agent is swallowed or non-traumaticly introduced through other natural routes.

* X-ray contrast agents (drugs) are a category of diagnostic agents that differ in their ability to absorb X-ray radiation from biological tissues. They are used to identify structures of organs and systems that are not detected or poorly identified by conventional radiography, fluoroscopy, and computed tomography. * X-ray contrast agents are divided into two groups. The first group includes drugs that absorb X-ray radiation weaker than body tissues (X-ray negative), the second group includes drugs that absorb X-ray radiation to a much greater extent than biological tissues (X-ray positive).

*X-ray negative substances are gases: carbon dioxide (CO 2), nitrous oxide (N 2 O), air, oxygen. They are used for contrasting the esophagus, stomach, duodenum and colon alone or in combination with X-ray positive substances (the so-called double contrast), to detect pathology of the thymus and esophagus (pneumomediastinum), and for radiography of large joints (pneumoarthrography).

*Barium sulfate is most widely used in radiopaque studies of the gastrointestinal tract. It is used in the form of an aqueous suspension, to which stabilizers, antifoaming and tanning agents, and flavoring agents are also added to increase the stability of the suspension, greater adhesion to the mucous membrane, and improve taste.

*If a foreign body is suspected in the esophagus, a thick paste of barium sulfate is used, which is given to the patient to swallow. In order to speed up the passage of barium sulfate, for example when examining the small intestine, it is administered chilled or lactose is added to it.

*Among iodine-containing radiopaque agents, water-soluble organic iodine compounds and iodized oils are mainly used. * The most widely used are water-soluble organic iodine compounds, in particular verografin, urografin, iodamide, triomblast. When administered intravenously, these drugs are mainly excreted by the kidneys, which is the basis of the urography technique, which allows one to obtain a clear image of the kidneys, urinary tract, and bladder.

* Water-soluble organic iodine-containing contrast agents are also used for all main types of angiography, X-ray studies of the maxillary (maxillary) sinuses, pancreatic duct, excretory ducts of the salivary glands, fistulography

* Liquid organic iodine compounds mixed with viscosity carriers (perafermented, ioduron B, propyliodone, chitrast), relatively quickly released from the bronchial tree, are used for bronchography, organoiodine compounds are used for lymphography, as well as for contrasting the meningeal spaces of the spinal cord and ventriculography

*Organic iodine-containing substances, especially water-soluble ones, cause side effects (nausea, vomiting, urticaria, itching, bronchospasm, laryngeal edema, Quincke's edema, collapse, cardiac arrhythmia, etc.), the severity of which is largely determined by the method, place and speed of administration , dose of the drug, individual sensitivity of the patient and other factors *Modern radiopaque agents have been developed that have significantly less pronounced side effects. These are the so-called dimeric and nonionic water-soluble organic iodine-substituted compounds (iopamidol, iopromide, omnipaque, etc.), which cause significantly fewer complications, especially during angiography.

The use of iodine-containing drugs is contraindicated in patients with hypersensitivity to iodine, severely impaired liver and kidney function, and acute infectious diseases. If complications arise as a result of the use of radiocontrast drugs, emergency antiallergic measures are indicated - antihistamines, corticosteroids, intravenous administration of sodium thiosulfate solution, and if blood pressure drops - antishock therapy.

*Magnetic resonance imaging scanners *Low-field (magnetic field strength 0.02 - 0.35 T) *Mid-field (magnetic field strength 0.35 - 1.0 T) *High-field (magnetic field strength 1.0 T and higher - as a rule , more than 1.5 T)

*Magnetic resonance imaging scanners *Magnet that creates a constant high-intensity magnetic field (to create the NMR effect) *Radio frequency coil that generates and receives radiofrequency pulses (surface and volumetric) *Gradient coil (to control the magnetic field in order to obtain MR sections) * Information processing unit (computer)

* Magnetic resonance imaging scanners Types of magnets Advantages 1) low power consumption 2) low operating costs Fixed costs 3) small field of uncertain reception 1) low cost Resistive 2) low mass (electromagnet 3) ability to control the nit) field 1) high field strength Superwire 2) high field uniformity 3) low power consumption Disadvantages 1) limited field strength (up to 0.3 T) 2) high mass 3) no possibility of field control 1) high power consumption 2) limited field strength (up to 0.2 T) 3) large field of uncertain reception 1) high cost 2) high expenses 3) technical complexity

*T 1 and T 2 -weighted images T 1 -weighted image: hypointense cerebrospinal fluid T 2 -weighted image: hyperintense cerebrospinal fluid

*Contrast agents for MRI *Paramagnets - increase the intensity of the MR signal by shortening the T1 relaxation time and are “positive” agents for contrast - extracellular (compounds DTPA, EDTA and their derivatives - with Mn and Gd) - intracellular (Mn- DPDP, Mn. Cl 2) – receptor *Superparamagnetic agents – reduce the intensity of the MR signal by lengthening the T 2 relaxation time and are “negative” agents for contrast – Fe 2 O 3 complexes and suspensions

*Advantages of magnetic resonance imaging * The highest resolution among all medical imaging methods * * No radiation exposure * Additional capabilities (MR angiography, three-dimensional reconstruction, MRI with contrast, etc.) Possibility of obtaining primary diagnostic images in different planes (axial, frontal, sagittal, etc.)

*Disadvantages of magnetic resonance imaging *Low availability, high cost *Long MR scanning time (difficulty in studying moving structures) *Inability to study patients with certain metal structures (ferro- and paramagnetic) *Difficulty in assessing a large amount of visual information (the boundary between normal and pathological)

One of the modern methods for diagnosing various diseases is computed tomography (CT, Engels, Saratov). Computed tomography is a method of layer-by-layer scanning of the studied areas of the body. Based on data on tissue absorption of X-rays, the computer creates an image of the required organ in any selected plane. The method is used for a detailed study of internal organs, blood vessels, bones and joints.

CT myelography is a method that combines the capabilities of CT and myelography. It is classified as an invasive imaging method, since it requires the introduction of a contrast agent into the subarachnoid space. Unlike X-ray myelography, CT myelography requires a smaller amount of contrast agent. Currently, CT myelography is used in hospital settings to determine the patency of the cerebrospinal fluid spaces of the spinal cord and brain, occlusive processes, various types of nasal liquorrhea, and to diagnose cystic processes of intracranial and spinal-paravertebral localization.

Computed angiography in its information content is close to conventional angiography and, unlike conventional angiography, is carried out without complex surgical procedures associated with inserting an intravascular catheter to the organ being examined. The advantage of CT angiography is that it allows the study to be carried out on an outpatient basis within 40-50 minutes, completely eliminates the risk of complications from surgical procedures, reduces radiation exposure to the patient and reduces the cost of the study.

The high resolution of spiral CT allows the construction of volumetric (3 D) models of the vascular system. As equipment improves, the speed of research is constantly decreasing. Thus, the time of data recording during CT angiography of vessels of the neck and brain on a 6-spiral scanner takes from 30 to 50 s, and on a 16-spiral scanner - 15-20 s. Currently, this research, including 3D processing, is carried out almost in real time.

* Examination of the abdominal organs (liver, gall bladder, pancreas) is carried out on an empty stomach. * Half an hour before the study, contrasting of the loops of the small intestine is carried out for a better view of the head of the pancreas and the hepatobiliary zone (you need to drink from one to three glasses of a contrast agent solution). * When examining the pelvic organs, it is necessary to do two cleansing enemas: 6-8 hours and 2 hours before the examination. Before the examination, the patient needs to drink a large amount of fluid to fill the bladder within an hour. *Preparation

*X-ray CT scans expose the patient to X-rays just like conventional x-rays, but the total radiation dose is usually higher. Therefore, RCT should be performed only for medical reasons. It is not advisable to perform RCT during pregnancy and without special need for young children. *Exposure to ionizing radiation

*X-ray rooms for various purposes must have a mandatory set of mobile and personal radiation protection equipment given in Appendix 8 of San. Pi. N 2. 6. 1. 1192 -03 “Hygienic requirements for the design and operation of X-ray rooms, devices and the conduct of X-ray examinations.”

*X-ray rooms should be centrally located at the junction of the hospital and clinic in medical institutions. It is allowed to place such offices in extensions of residential buildings and on the ground floors.

* To protect personnel, the following hygiene requirements are used: for honey. for personnel, the average annual effective dose is 20 m 3 V (0.02 sieverts) or the effective dose over a working period (50 years) is 1 sievert.

* For practically healthy people, the annual effective dose when conducting preventive medical X-ray examinations should not exceed 1 m 3 V (0.001 sievert)

Protection against X-ray radiation allows you to protect a person only when using the device in medical institutions. Today there are several types of protective equipment, which are divided into groups: collective protective equipment, they have two subtypes: stationary and mobile; means against direct unused rays; equipment for service personnel; protective equipment intended for patients.

* The time spent in the X-ray source sphere should be minimal. Distance from the X-ray source. For diagnostic studies, the minimum distance between the focus of the X-ray tube and the object being examined is 35 cm (skin-focal distance). This distance is ensured automatically by the design of the transmission and recording device.

* Walls and partitions consist of 2-3 layers of putty, painted with special medical paint. The floors are also made layer by layer from special materials.

* Ceilings are waterproofed, laid out in 2-3 layers of special. materials with lead. Painted with medical paint. Sufficient lighting.

* The door in the X-ray room must be metal with a sheet of lead. The color is (usually) white or gray with the obligatory “danger” sign. Window frames must be made of the same materials.

* For personal protection, the following are used: a protective apron, collar, vest, skirt, glasses, cap, gloves with mandatory lead coating.

* Mobile protective equipment includes: small and large screens for both staff and patients, a protective screen or curtain made of metal or special fabric with a sheet of lead.

When using devices in the X-ray room, everything must work properly and comply with the regulated instructions for using the devices. Markings of the tools used are required.

Single-photon emission computed tomography is especially widely used in cardiological and neurological practice. The method is based on rotating a conventional gamma camera around the patient's body. Registration of radiation at various points of the circle allows one to reconstruct a sectional image. *SPECT

SPECT is used in cardiology, neurology, urology, pulmonology, for the diagnosis of brain tumors, for scintigraphy of breast cancer, liver diseases and skeletal scintigraphy. This technology allows the formation of 3D images, in contrast to scintigraphy, which uses the same principle of creating gamma photons, but creates only a two-dimensional projection.

SPECT uses radiopharmaceuticals labeled with radioisotopes, the nuclei of which emit only one gamma quantum (photon) during each event of radioactive decay (for comparison, PET uses radioisotopes that emit positrons)

*PET Positron emission tomography is based on the use of positrons emitted by radionuclides. Positrons, having the same mass as electrons, are positively charged. The emitted positron immediately interacts with a nearby electron, resulting in two gamma-ray photons traveling in opposite directions. These photons are recorded by special detectors. The information is then transferred to a computer and converted into a digital image.

Positrons arise from the positron beta decay of a radionuclide that is part of a radiopharmaceutical that is introduced into the body before the study.

PET makes it possible to quantify the concentration of radionuclides and thereby study metabolic processes in tissues.

The choice of a suitable radiopharmaceutical makes it possible to study using PET such different processes as metabolism, transport of substances, ligand-receptor interactions, gene expression, etc. The use of radiopharmaceuticals belonging to various classes of biologically active compounds makes PET a fairly universal tool of modern medicine. Therefore, the development of new radiopharmaceuticals and effective methods for the synthesis of already proven drugs is currently becoming a key stage in the development of the PET method.

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Scintigraphy - (from Latin scinti - sparkle and Greek grapho - depict, write) a method of functional visualization that consists of introducing radioactive isotopes (RP) into the body and obtaining a two-dimensional image by determining the radiation emitted by them

Radioactive tracers have found their use in medicine since 1911; their founder was György de Heves, for which he received the Nobel Prize. Since the fifties, the field began to actively develop, radionuclides came into practice, and it became possible to observe their accumulation in the desired organ and distribution throughout it. In the 2nd half of the 20th century, with the development of technologies for creating large crystals, a new device was created - a gamma camera, the use of which made it possible to obtain images - scintigrams. This method is called scintigraphy.

*The essence of the method This diagnostic method is as follows: the patient is injected, most often intravenously, with a drug that consists of a vector molecule and a marker molecule. A vector molecule has an affinity for a specific organ or entire system. It is she who is responsible for ensuring that the marker is concentrated exactly where it is needed. The marker molecule has the ability to emit γ-rays, which, in turn, are captured by the scintillation camera and transformed into a readable result.

*The resulting images are Static - the result is a flat (two-dimensional) image. This method most often examines bones, the thyroid gland, etc. Dynamic - the result of adding several static ones, obtaining dynamic curves (for example, when studying the function of the kidneys, liver, gall bladder) ECG-synchronized study - ECG synchronization allows visualization of the contractile function of the heart in tomographic mode .

Scintigraphy is sometimes referred to as a related method, single-photon emission computed tomography (SPECT), which allows one to obtain tomograms (three-dimensional images). Most often, the heart (myocardium) and brain are examined in this way

*Use of the Scintigraphy method is indicated for suspected presence of some pathology, for an existing or previously identified disease, to clarify the degree of organ damage, the functional activity of the pathological focus and assess the effectiveness of the treatment

*Objects of study of the endocrine gland hematopoietic system spinal cord and brain (diagnosis of infectious diseases of the brain, Alzheimer's disease, Parkinson's disease) lymphatic system lungs cardiovascular system (study of myocardial contractility, detection of ischemic foci, detection of pulmonary embolism) digestive organs excretory organs skeletal system (diagnosis of fractures, inflammation, infections, bone tumors)

Isotopes are specific to a particular organ, so different radiopharmaceuticals are used to detect the pathology of different organs. To study the heart, Thallium-201, Technetium-99 m is used, the thyroid gland - Iodine-123, the lungs - Technetium-99 m, Iodine-111, the liver - Technetium-97 m, and so on.

*Criteria for selecting radiopharmaceuticals The main criterion for selection is the ratio of diagnostic value/minimum radiation exposure, which can be manifested in the following: The drug must quickly reach the organ under study, be evenly distributed in it and also quickly and completely eliminated from the body. The half-life of the radioactive part of the molecule must be short enough so that the radionuclide does not pose any harm to the patient's health. Radiation that is characteristic of a given drug should be convenient for registration. Radiopharmaceuticals must not contain impurities toxic to humans and must not generate decay products with a long decomposition period

*Studies requiring special preparation 1. Functional study of the thyroid gland using 131 sodium iodide. For 3 months before the study, patients are prohibited from: conducting an X-ray contrast study; taking medications containing iodine; 10 days before the study, sedatives containing iodine in high concentrations are removed. The patient is sent to the radioisotope diagnostics department in the morning on an empty stomach. 30 minutes after taking radioactive iodine, the patient can have breakfast

2. Scintigraphy of the thyroid gland using 131-sodium iodide. The patient is sent to the department in the morning on an empty stomach. 30 minutes after taking radioactive iodine, the patient is given a regular breakfast. Thyroid scintigraphy is performed 24 hours after taking the drug. 3. Myocardial scintigraphy using 201-thallium chloride. Performed on an empty stomach. 4. Dynamic scintigraphy of the bile ducts with hida The study is carried out on an empty stomach. A hospital nurse brings 2 raw eggs to the radioisotope diagnostics department. 5. Scintigraphy of the skeletal system with pyrophosphate The patient, accompanied by a nurse, is sent to the isotope diagnostic department for intravenous administration of the drug in the morning. The study is carried out after 3 hours. Before starting the study, the patient must empty the bladder.

*Studies that do not require special preparation Liver scintigraphy Radiometric examination of skin tumors. Renography and scintigraphy of the kidneys Angiography of the kidneys and abdominal aorta, vessels of the neck and brain Scintigraphy of the pancreas. Lung scintigraphy. BCC (determination of circulating blood volume) Transmission-emission study of the heart, lungs and large vessels Scintigraphy of the thyroid gland using pertechnetate Phlebography Lymphography Determination of ejection fraction

*Contraindications An absolute contraindication is an allergy to substances contained in the radiopharmaceutical used. A relative contraindication is pregnancy. Examination of a breastfeeding patient is allowed, but it is important not to resume feeding earlier than 24 hours after the examination, more precisely after administration of the drug

*Side effects Allergic reactions to radioactive substances Temporary increase or decrease in blood pressure Frequent urge to urinate

*Positive aspects of the study The ability to determine not only the appearance of the organ, but also dysfunction, which often manifests itself much earlier than organic lesions. With such a study, the result is recorded not in the form of a static two-dimensional picture, but in the form of dynamic curves, tomograms or electrocardiograms. Based on the first point, it becomes obvious that scintigraphy makes it possible to quantify the damage to an organ or system. This method requires virtually no preparation on the part of the patient. Often, it is only recommended to follow a certain diet and stop taking medications that may interfere with visualization

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Interventional radiology is a branch of medical radiology that develops the scientific foundations and clinical application of therapeutic and diagnostic procedures carried out under the control of radiation research. Formation of R. and. became possible with the introduction of electronics, automation, television, and computer technology into medicine.

Surgical interventions performed using interventional radiology can be divided into the following groups: * restoration of the lumen of narrowed tubular structures (arteries, biliary tract, various parts of the gastrointestinal tract); *drainage of cavity formations in internal organs; *occlusion of the lumen of blood vessels *Purposes of application

Indications for interventional interventions are very wide, which is associated with the variety of problems that can be solved using interventional radiology methods. General contraindications are the serious condition of the patient, acute infectious diseases, mental disorders, decompensation of the functions of the cardiovascular system, liver, kidneys, and when using iodine-containing radiocontrast agents - increased sensitivity to iodine preparations. *Indications

The development of interventional radiology required the creation of a specialized office within the radiology department. Most often, this is an angiography room for intracavitary and intravascular studies, serviced by an x-ray surgical team, which includes an x-ray surgeon, an anesthesiologist, an ultrasound specialist, an operating nurse, an x-ray technician, a nurse, and a photo lab assistant. Employees of the X-ray surgical team must be proficient in intensive care and resuscitation methods.

X-ray endovascular interventions, which have received the most recognition, are intravascular diagnostic and therapeutic procedures performed under X-ray control. Their main types are x-ray endovascular dilatation, or angioplasty, x-ray endovascular prosthetics and x-ray endovascular occlusion

Extravasal interventional interventions include endobronchial, endobiliary, endoesophageal, endourinal and other manipulations. X-ray endobronchial interventions include catheterization of the bronchial tree, performed under the control of X-ray television illumination, in order to obtain material for morphological studies from areas inaccessible to the bronchoscope. With progressive strictures of the trachea, with softening of the cartilage of the trachea and bronchi, endoprosthetics is performed using temporary and permanent metal and nitinol prostheses.

* In 1986, Roentgen discovered a new type of radiation, and already in the same year talented scientists managed to make the vessels of various organs of a corpse radiopaque. However, limited technical capabilities have hampered the development of vascular angiography for some time. * Currently, vascular angiography is a fairly new, but rapidly developing high-tech method for diagnosing various diseases of blood vessels and human organs.

* On standard x-rays it is impossible to see either arteries, veins, lymphatic vessels, much less capillaries, since they absorb radiation, just like the soft tissues surrounding them. Therefore, in order to be able to examine the vessels and assess their condition, special angiography methods are used with the introduction of special radiopaque agents.

Depending on the location of the affected vein, several types of angiography are distinguished: 1. Cerebral angiography - study of cerebral vessels. 2. Thoracic aortography – study of the aorta and its branches. 3. Pulmonary angiography – image of the pulmonary vessels. 4. Abdominal aortography – examination of the abdominal aorta. 5. Renal arteriography - detection of tumors, kidney injuries and urolithiasis. 6. Peripheral arteriography - assessment of the condition of the arteries of the extremities in injuries and occlusive diseases. 7. Portography - study of the portal vein of the liver. 8. Phlebography is a study of the vessels of the extremities to determine the nature of venous blood flow. 9. Fluorescein angiography is a study of blood vessels used in ophthalmology. *Types of angiography

Angiography is used to identify pathologies of the blood vessels of the lower extremities, in particular stenosis (narrowing) or blockage (occlusion) of arteries, veins and lymphatic ducts. This method is used for: * identifying atherosclerotic changes in the bloodstream, * diagnosing heart disease, * assessing kidney function; * detection of tumors, cysts, aneurysms, blood clots, arteriovenous shunts; * diagnosis of retinal diseases; * preoperative examination before surgery on the open brain or heart. *Indications for the study

The method is contraindicated for: * venography of thrombophlebitis; * acute infectious and inflammatory diseases; * mental illnesses; * allergic reactions to iodine-containing drugs or contrast agents; * severe renal, liver and heart failure; * patient's serious condition; * thyroid dysfunction; * sexually transmitted diseases. The method is contraindicated for patients with bleeding disorders, as well as for pregnant women due to the negative effects of ionizing radiation on the fetus. *Contraindications

1. Vascular angiography is an invasive procedure that requires medical monitoring of the patient’s condition before and after the diagnostic procedure. Because of these features, it is necessary to hospitalize the patient in a hospital and conduct laboratory tests: a general blood test, urine test, biochemical blood test, determination of blood group and Rh factor and a number of other tests as indicated. The person is advised to stop taking certain medications that affect the blood clotting system (for example, aspirin) several days before the procedure. *Preparation for the study

2. The patient is advised to refrain from eating 6-8 hours before the start of the diagnostic procedure. 3. The procedure itself is carried out using local anesthetics, and the person is usually prescribed sedatives (calming) drugs on the eve of the test. 4. Before angiography, each patient is tested for an allergic reaction to the drugs used in contrast. *Preparation for the study

* After pre-treatment with antiseptic solutions and local anesthesia, a small skin incision is made and the necessary artery is found. It is pierced with a special needle and a metal conductor is inserted through this needle to the desired level. A special catheter is inserted along this conductor to a given point, and the conductor along with the needle is removed. All manipulations taking place inside the vessel occur strictly under the control of X-ray television. A radiopaque substance is injected into the vessel through a catheter and at the same moment a series of X-rays are taken, changing the patient’s position if necessary. *Angiography technique

*After the procedure is completed, the catheter is removed, and a very tight sterile bandage is applied to the puncture area. The substance introduced into the vessel leaves the body through the kidneys within 24 hours. The procedure itself lasts about 40 minutes. *Angiography technique

* The patient's condition after the procedure * The patient is prescribed bed rest for 24 hours. The patient’s well-being is monitored by the attending doctor, who measures body temperature and examines the area of ​​invasive intervention. The next day, the bandage is removed and if the person’s condition is satisfactory and there is no bleeding in the puncture area, he is sent home. * For the vast majority of people, angiography does not pose any risk. According to available data, the risk of complications during angiography does not exceed 5%.

*Complications Among the complications, the most common are the following: * Allergic reactions to X-ray contrast agents (in particular those containing iodine, since they are used most often) * Pain, swelling and hematomas at the site of catheter insertion * Bleeding after puncture * Impaired kidney function up to the development of renal failure * Injury to a vessel or tissue of the heart * Heart rhythm disturbances * Development of cardiovascular failure * Heart attack or stroke