Chapter 2

For more than 100 years, rays of a special kind have been known, occupying a large part of the spectrum of electromagnetic waves. On November 8, 1895, Wilhelm Conrad Roentgen (1845-1923), professor of physics at the University of Würzburg, drew attention to an amazing phenomenon. While studying the operation of an electrovacuum (cathode) tube in his laboratory, he noticed that when a high voltage current was applied to its electrodes, the nearby platinum-cyanogen barium began to emit a greenish glow. Such a glow of luminescent substances under the influence of cathode rays emanating from an electrovacuum tube was already known by that time. However, on the X-ray table, the tube was tightly wrapped in black paper during the experiment, and although the platinum-cyanogen barium was at a considerable distance from the tube, its glow resumed with each application of electric current to the tube (see Fig. 2.1).

Fig.2.1. Wilhelm Conrad Rice. 2.2. X-ray of cis-

Roentgen (1845-1923) ty wife of VK Roentgen Berta

Roentgen came to the conclusion that some kind of rays unknown to science arise in the tube, capable of penetrating through solid bodies and propagating in the air over distances measured in meters. The first radiograph in the history of mankind was the image of the brush of Roentgen's wife (see Fig. 2.2).

Rice. 2.3.Spectrum of electromagnetic radiation

Roentgen's first preliminary report "On a new form of rays" was published in January 1896. In three subsequent public reports in 1896-1897. he formulated all the properties of unknown rays he had discovered and pointed out the technique of their appearance.

In the first days after the publication of Roentgen's discovery, his materials were translated into many foreign languages, including Russian. Petersburg University and the Military Medical Academy already in January 1896 X-rays were used to take pictures of human limbs, and later of other organs. Soon, the inventor of the radio, A. S. Popov, manufactured the first domestic X-ray machine, which functioned in the Kronstadt hospital.

Roentgen was the first among physicists in 1901 to be awarded the Nobel Prize for his discovery, which was awarded to him in 1909. By the decision of the First International Congress on Roentgenology in 1906, X-rays were named X-rays.

Within a few years, specialists dedicated to radiology appeared in many countries. X-ray departments and offices appeared in hospitals, scientific societies of radiologists arose in large cities, corresponding departments were organized at the medical faculties of universities.

X-rays are one of the types of electromagnetic waves that occupy a place in the general wave spectrum between ultraviolet rays and γ-rays. They differ from radio waves, infrared radiation, visible light and ultraviolet radiation in a shorter wavelength (see Fig. 2.3).

The propagation speed of X-rays is equal to the speed of light - 300,000 km/s.

The following are currently known properties of x-rays. X-rays have penetrating ability. Roentgen reported that the ability of rays to penetrate through various media back

proportional to the specific gravity of these media. Due to the short wavelength, X-rays can penetrate objects that are opaque to visible light.

X-rays are capable absorb and dissipate. When absorbed, part of the X-rays with the longest wavelength disappears, completely transferring their energy to the substance. When scattered, some of the rays deviate from the original direction. Scattered X-ray radiation does not carry useful information. Some of the rays completely pass through the object with a change in their characteristics. Thus, an invisible image is formed.

X-rays, passing through some substances, cause them fluorescence (glow). Substances with this property are called phosphors and are widely used in radiology (fluoroscopy, fluorography).

X-rays provide photochemical action. Like visible light, falling on a photographic emulsion, they act on silver halides, causing a chemical reaction to reduce silver. This is the basis for image registration on photosensitive materials.

X-rays cause ionization of matter.

X-rays provide biological action, related to their ionizing ability.

X-rays propagate straightforward, therefore, the x-ray image always repeats the shape of the object under study.

X-rays are characteristic polarization- distribution in a certain plane.

Diffraction and interference inherent in x-rays, as well as other electromagnetic waves. X-ray spectroscopy and X-ray structural analysis are based on these properties.

X-rays invisible.

Any X-ray diagnostic system includes 3 main components: an X-ray tube, an object of study (patient) and an X-ray image receiver.

x-ray tube consists of two electrodes (anode and cathode) and a glass bulb (Fig. 2.4).

When a filament current is applied to the cathode, its spiral filament is strongly heated (heated up). A cloud of free electrons appears around it (the phenomenon of thermionic emission). As soon as a potential difference arises between the cathode and anode, free electrons rush to the anode. The speed of the electrons is directly proportional to the magnitude of the voltage. When electrons decelerate in the anode material, part of their kinetic energy goes into the production of X-rays. These rays freely go beyond the X-ray tube and propagate in different directions.

X-rays, depending on the method of occurrence, are divided into primary (stagnation rays) and secondary (characteristic rays).

Rice. 2.4. Schematic diagram of an x-ray tube: 1 - cathode; 2 - anode; 3 - glass flask; 4 - electron flow; 5 - X-ray beam

primary rays. Electrons, depending on the direction of the main transformer, can move in x-ray tubes at different speeds, approaching the speed of light at the highest voltage. Upon impact with the anode, or, as they say, during braking, the kinetic energy of the flight of electrons is converted for the most part into thermal energy, which heats the anode. A smaller part of the kinetic energy is converted into deceleration X-rays. The wavelength of the rays of deceleration depends on the speed of the flight of electrons: the greater it is, the shorter the wavelength. The penetrating power of rays depends on the wavelength (the shorter the wave, the greater its penetrating power).

By changing the voltage of the transformer, one can control the speed of the electrons and obtain either strongly penetrating (so-called hard) or weakly penetrating (so-called soft) x-rays.

Secondary (characteristic) rays. They arise in the process of deceleration of electrons, but the length of their waves depends solely on the structure of the atoms of the anode material.

The fact is that the energy of electron flight in the tube can reach such values that when electrons hit the anode, energy will be released that is sufficient to make the electrons of the inner orbits of the atoms of the anode substance “jump” to the outer orbits. In such cases, the atom returns to its state, because from its outer orbits there will be a transition of electrons to free inner orbits with the release of energy. The excited atom of the anode substance returns to the state of rest. Characteristic radiation arises as a result of changes in the inner electronic layers of atoms. The layers of electrons in an atom are strictly defined

for each element and depend on its place in the periodic system of Mendeleev. Consequently, the secondary rays received from a given atom will have waves of a strictly defined length, which is why these rays are called characteristic.

The formation of an electron cloud on the cathode spiral, the flight of electrons to the anode, and the production of X-rays are possible only under vacuum conditions. For its creation and serves x-ray tube bulb made of durable glass capable of transmitting x-rays.

As x-ray image receivers can act: X-ray film, selenium plate, fluorescent screen, as well as special detectors (with digital imaging methods).

X-RAY TECHNIQUES

All the numerous methods of X-ray examination are divided into general and special.

To general include techniques designed to study any anatomical regions and performed on general-purpose x-ray machines (fluoroscopy and radiography).

A number of methods should also be referred to the general ones, in which it is also possible to study any anatomical regions, but either special equipment (fluorography, radiography with direct magnification of the image) or additional devices for conventional x-ray machines (tomography, electroroentgenography) are required. Sometimes these techniques are also called private.

To special techniques include those that allow you to get an image on special installations designed to study certain organs and areas (mammography, orthopantomography). Special techniques also include a large group of X-ray contrast studies, in which images are obtained using artificial contrast (bronchography, angiography, excretory urography, etc.).

GENERAL X-RAY EXAMINATION TECHNIQUES

Fluoroscopy- a research technique in which an image of an object is obtained on a luminous (fluorescent) screen in real time. Some substances fluoresce intensely when exposed to x-rays. This fluorescence is used in X-ray diagnostics using cardboard screens coated with a fluorescent substance.

The patient is installed (lay down) on a special tripod. X-rays, passing through the body of the patient (the area of interest to the researcher), fall on the screen and cause it to glow - fluorescence. The fluorescence of the screen is not equally intense - it is the brighter, the more X-rays hit one or another point of the screen. On screen

the fewer rays hit, the more dense obstacles will be on their way from the tube to the screen (for example, bone tissue), and also the thicker the tissue through which the rays pass.

The glow of the fluorescent screen is very weak, so X-rays were taken in the dark. The image on the screen was poorly distinguishable, small details were not differentiated, and the radiation exposure in such a study was quite high.

As an improved method of fluoroscopy, X-ray television transmission is used with the help of an X-ray image amplifier - an image intensifier tube (IOC) and a closed-circuit television system. In the image intensifier tube, the visible image on the fluorescent screen is amplified, converted into an electrical signal, and displayed on the display screen.

The x-ray image on the display, like a conventional television image, can be studied in a lighted room. Radiation exposure to the patient and staff when using image intensifier tubes is much less. The telesystem allows you to record all stages of the study, including the movement of organs. In addition, the image can be transmitted via a TV channel to monitors located in other rooms.

During X-ray examination, a positive planar black-and-white summation image is formed in real time. When moving the patient relative to the X-ray emitter, they speak of polypositional, and when moving the X-ray emitter relative to the patient, they speak of a polyprojective study; both of them allow to obtain more complete information about the pathological process.

However, fluoroscopy, both with and without an image intensifier tube, has a number of disadvantages that narrow the scope of the method. First, the radiation exposure from fluoroscopy remains relatively high (much higher than from radiography). Secondly, the technique has a low spatial resolution (the ability to consider and evaluate fine details is lower than with radiography). In this regard, it is advisable to supplement fluoroscopy with the production of images. It is also necessary to objectify the results of the study and the possibility of their comparison in the dynamic monitoring of the patient.

Radiography- This is a technique of X-ray examination, in which a static image of an object is obtained, fixed on any information carrier. Such carriers can be X-ray film, photographic film, digital detector, etc. An image of any anatomical region can be obtained on radiographs. Pictures of the entire anatomical region (head, chest, abdomen) are called review(Fig. 2.5). Pictures showing a small part of the anatomical region that is of most interest to the doctor are called aiming(Fig. 2.6).

Some organs are clearly visible in the images due to the natural contrast (lungs, bones) (see Fig. 2.7); others (stomach, intestines) are clearly displayed on radiographs only after artificial contrasting (see Fig. 2.8).

Rice. 2.5.Plain radiograph of the lumbar spine in lateral projection. Compression but-os-ringed fracture of the L1 vertebral body

Rice. 2.6.

Periapical radiograph of L1 vertebra in lateral view

Passing through the object of study, X-ray radiation is delayed to a greater or lesser extent. Where the radiation is delayed more, areas are formed shading; where is less enlightenment.

The x-ray image may be negative or positive. So, for example, in a negative image, the bones look light, air - dark, in a positive image - vice versa.

The x-ray image is black and white and planar (summation).

Advantages of radiography over fluoroscopy:

Great resolution;

Possibility of evaluation by many researchers and retrospective study of the image;

The possibility of long-term storage and comparison of images with repeated images in the process of dynamic monitoring of the patient;

Reducing radiation exposure to the patient.

The disadvantages of radiography include an increase in material costs when using it (radiographic film, photoreagents, etc.) and obtaining the desired image not immediately, but after a certain time.

The radiography technique is available to all medical institutions and is used everywhere. X-ray machines of various types make it possible to perform radiography not only in the conditions of the X-ray room, but also outside it (in the ward, in the operating room, etc.), as well as in non-stationary conditions.

The development of computer technology has made it possible to develop a digital (digital) method for obtaining an x-ray image (from the English. digital- "number"). In digital devices, an x-ray image from an image intensifier tube enters a special device - an analog-to-digital converter (ADC), in which an electrical signal that carries information about an x-ray image is encoded into digital form. Entering then into the computer, the digital information is processed in it according to pre-compiled programs, the choice of which depends on the objectives of the study. The transformation of a digital image into an analog, visible one takes place in a digital-to-analog converter (DAC), the function of which is opposite to the ADC.

The main advantages of digital radiography over traditional radiography are: fast image acquisition, wide possibilities for its post-processing processing (brightness and contrast correction, noise suppression, electronic magnification of the image of the area of interest, predominant selection of bone or soft tissue structures, etc.), the absence of a photolaboratory process, and electronic archiving of images.

In addition, the computerization of X-ray equipment allows you to quickly transfer images over long distances without loss of quality, including to other medical institutions.

Rice. 2.7.Radiographs of the ankle joint in frontal and lateral projections

Rice. 2.8.X-ray of the colon, contrasted with a suspension of barium sulfate (irrigogram). Norm

Fluorography- photographing an x-ray image from a fluorescent screen onto photographic film of various formats. Such an image is always scaled down.

In terms of information content, fluorography is inferior to radiography, but when using large-frame fluorograms, the difference between these methods becomes less significant. In this regard, in medical institutions, in a number of patients with respiratory diseases, fluorography can replace radiography, especially during repeated studies. This type of fluoroscopy is called diagnostic.

The main purpose of fluorography, associated with the speed of its implementation (it takes about 3 times less time to perform a fluorogram than to perform a radiograph), are mass examinations to detect latent lung diseases. (preventive, or check, fluorography).

Fluorographic devices are compact, they can be mounted in a car body. This makes it possible to conduct mass examinations in areas where X-ray diagnostic equipment is not available.

Currently, film fluorography is increasingly being replaced by digital. The term "digital fluorographs" is to a certain extent conditional, since these devices do not photograph the x-ray image on film, i.e., fluorograms are not performed in the usual sense of the word. In fact, these fluorographs are digital radiographic devices designed primarily (but not exclusively) for examining the organs of the chest cavity. Digital fluorography has all the advantages inherent in digital radiography in general.

X-ray with direct magnification can only be used in the presence of special X-ray tubes in which the focal spot (the area from which X-rays come from the emitter) is very small (0.1-0.3 mm 2). An enlarged image is obtained by bringing the object under study closer to the x-ray tube without changing the focal length. As a result, radiographs show finer details that are indistinguishable in conventional images. The technique is used in the study of peripheral bone structures (hands, feet, etc.).

Electroradiography- a technique in which a diagnostic image is obtained not on an x-ray film, but on the surface of a selenium plate with transfer to paper. A plate uniformly charged with static electricity is used instead of a film cassette and, depending on the different amount of ionizing radiation that has hit different points on its surface, is discharged differently. A finely dispersed coal powder is sprayed onto the surface of the plate, which, according to the laws of electrostatic attraction, is distributed unevenly over the surface of the plate. A sheet of writing paper is placed on the plate, and the image is transferred to the paper as a result of the adhesion of carbon

powder. A selenium plate, unlike a film, can be used repeatedly. The technique is fast, economical, does not require a darkened room. In addition, selenium plates in an uncharged state are indifferent to the effects of ionizing radiation and can be used when working under conditions of an increased radiation background (X-ray film will become unusable under these conditions).

In general, electroroentgenography is only slightly inferior to film radiography in its information content, surpassing it in the study of bones (Fig. 2.9).

Linear tomography- method of layer-by-layer X-ray examination.

Rice. 2.9.An electroroentgenogram of the ankle joint in direct projection. Fracture of the fibula

As already mentioned, the summation image of the entire thickness of the studied part of the body is visible on the radiograph. Tomography serves to obtain an isolated image of structures located in the same plane, as if dividing the summation image into separate layers.

The effect of tomography is achieved due to the continuous movement during the shooting of two or three components of the x-ray system: x-ray tube (emitter) - patient - image receiver. Most often, the emitter and image receiver are moved, and the patient is motionless. The emitter and image receiver move in an arc, a straight line, or a more complex path, but always in opposite directions. With such a displacement, the image of most details on the tomogram turns out to be smeared, blurry, fuzzy, and the formations located at the level of the center of rotation of the emitter-receiver system are displayed most clearly (Fig. 2.10).

Linear tomography has a special advantage over radiography.

when organs are examined with dense pathological zones formed in them, completely obscuring certain areas of the image. In some cases, it helps to determine the nature of the pathological process, to clarify its localization and prevalence, to identify small pathological foci and cavities (see Fig. 2.11).

Structurally, tomographs are made in the form of an additional tripod, which can automatically move the X-ray tube along the arc. When the level of the center of rotation of the emitter - receiver changes, the depth of the resulting cut will change. The thickness of the studied layer is the smaller, the greater the amplitude of motion of the system mentioned above. If they choose very

small angle of movement (3-5°), then get the image of a thick layer. This type of linear tomography is called - zonography.

Linear tomography is widely used, especially in medical institutions that do not have computed tomography. The most common indications for tomography are diseases of the lungs and mediastinum.

SPECIAL TECHNIQUES

RADIOLOGICAL

RESEARCH

Orthopantomography- this is a variant of zoning, which allows you to get a detailed planar image of the jaws (see Fig. 2.12). In this case, a separate image of each tooth is achieved by sequentially shooting them with a narrow beam.

Rice. 2.10. Scheme for obtaining a tomographic image: a - the object under study; b - tomographic layer; 1-3 - sequential positions of the X-ray tube and the radiation receiver in the process of research

lump of x-rays on separate sections of the film. The conditions for this are created by a synchronous circular motion around the head of the patient of the x-ray tube and the image receiver, installed at opposite ends of the rotary stand of the apparatus. The technique allows you to explore other parts of the facial skeleton (paranasal sinuses, eye sockets).

Mammography- X-ray examination of the breast. It is performed to study the structure of the mammary gland when seals are found in it, as well as for a preventive purpose. milk jelly-

za is a soft tissue organ; therefore, to study its structure, it is necessary to use very small values of the anode voltage. There are special x-ray machines - mammographs, where x-ray tubes are installed with a focal spot the size of a fraction of a millimeter. They are equipped with special stands for laying the mammary gland with a device for its compression. This makes it possible to reduce the thickness of the gland tissue during the examination, thereby improving the quality of mammograms (see Fig. 2.13).

Techniques using artificial contrast

In order for organs invisible in ordinary photographs to be displayed on radiographs, they resort to the technique of artificial contrasting. The technique consists in the introduction into the body of substances,

Rice. 2.11. Linear tomogram of the right lung. At the apex of the lung there is a large air cavity with thick walls.

which absorb (or, conversely, transmit) radiation much stronger (or weaker) than the organ under study.

Rice. 2.12. Orthopantomogram

As contrast agents, substances are used either with a low relative density (air, oxygen, carbon dioxide, nitrous oxide), or with a large atomic mass (suspensions or solutions of salts of heavy metals and halides). The former absorb X-rays to a lesser extent than the anatomical structures (negative) the second - to a greater extent (positive). If, for example, air is introduced into the abdominal cavity (artificial pneumoperitoneum), then against its background the outlines of the liver, spleen, gallbladder, and stomach are clearly distinguished.

Rice. 2.13. Radiographs of the mammary gland in craniocaudal (a) and oblique (b) projections

For the study of organ cavities, high-atomic contrast agents are usually used, most often an aqueous suspension of barium sulfate and iodine compounds. These substances, largely delaying X-rays, give an intense shadow on the pictures, by which one can judge the position of the organ, the shape and size of its cavity, and the outlines of its inner surface.

There are two ways of artificial contrasting with the help of highly atomic substances. The first is the direct injection of a contrast agent into the cavity of an organ - the esophagus, stomach, intestines, bronchi, blood or lymphatic vessels, urinary tract, cavitary systems of the kidneys, uterus, salivary ducts, fistulous tracts, cerebrospinal fluid spaces of the brain and spinal cord, etc. d.

The second method is based on the specific ability of individual organs to concentrate certain contrast agents. For example, the liver, gallbladder, and kidneys concentrate and excrete some of the iodine compounds introduced into the body. After the introduction of such substances to the patient in the pictures after a certain time, the bile ducts, gall bladder, cavitary systems of the kidneys, ureters, bladder are distinguished.

The technique of artificial contrasting is currently the leading one in X-ray examination of most internal organs.

In x-ray practice, 3 types of radiopaque agents (RKS) are used: iodine-containing soluble, gaseous, aqueous suspension of barium sulfate. The main tool for the study of the gastrointestinal tract is an aqueous suspension of barium sulfate. For the study of blood vessels, heart cavities, urinary tract, water-soluble iodine-containing substances are used, which are injected either intravascularly or into the cavity of organs. Gases are almost never used as contrast agents.

When choosing contrast agents for research, RCD should be evaluated from the standpoint of the severity of the contrasting effect and harmlessness.

The harmlessness of RCM, in addition to the obligatory biological and chemical inertness, depends on their physical characteristics, of which the most significant are osmolarity and electrical activity. Os-molarity is determined by the number of ions or PKC molecules in solution. Regarding blood plasma, the osmolarity of which is 280 mOsm / kg H 2 O, contrast agents can be high osmolar (more than 1200 mOsm / kg H 2 O), low osmolar (less than 1200 mOsm / kg H 2 O) or isoosmolar (equivalent in osmolarity to blood) .

High osmolarity adversely affects the endothelium, erythrocytes, cell membranes, proteins, so low-osmolar RCS should be preferred. Optimal RCS, isoosmolar with blood. It should be remembered that the osmolarity of PKC, both lower and higher than the osmolarity of blood, makes these drugs adversely affect blood cells.

In terms of electrical activity, radiopaque preparations are divided into: ionic, decomposing in water into electrically charged particles, and non-ionic, electrically neutral. The osmolarity of ionic solutions, due to the greater content of particles in them, is twice that of non-ionic ones.

Non-ionic contrast agents have a number of advantages compared to ionic ones: significantly lower (3-5 times) overall toxicity, give a much less pronounced vasodilation effect, cause

less deformation of erythrocytes and much less release of histamine, activate the complement system, inhibit cholinesterase activity, which reduces the risk of negative side effects.

Thus, non-ionic RCMs provide the greatest assurance in terms of both safety and contrast quality.

The widespread introduction of contrasting various organs with these preparations has led to the emergence of numerous methods of X-ray examination, which significantly increase the diagnostic capabilities of the X-ray method.

Diagnostic pneumothorax- X-ray examination of the respiratory organs after the introduction of gas into the pleural cavity. It is performed in order to clarify the localization of pathological formations located on the border of the lung with neighboring organs. With the advent of the CT method, it is rarely used.

Pneumomediastinography- X-ray examination of the mediastinum after the introduction of gas into its tissue. It is performed in order to clarify the localization of pathological formations (tumors, cysts) identified in the images and their spread to neighboring organs. With the advent of the CT method, it is practically not used.

Diagnostic pneumoperitoneum- X-ray examination of the diaphragm and organs of the abdominal cavity after the introduction of gas into the peritoneal cavity. It is performed in order to clarify the localization of pathological formations identified in the images against the background of the diaphragm.

pneumoretroperitoneum- a technique for X-ray examination of organs located in the retroperitoneal tissue by introducing gas into the retroperitoneal tissue in order to better visualize their contours. With the introduction of ultrasound, CT and MRI into clinical practice, it is practically not used.

Pneumoren- X-ray examination of the kidney and adjacent adrenal gland after the introduction of gas into the perirenal tissue. Currently, it is extremely rare.

Pneumopyelography- study of the cavitary system of the kidney after filling it with gas through the ureteral catheter. It is currently used mainly in specialized hospitals for the detection of intrapelvic tumors.

Pneumomyelography- X-ray examination of the subarachnoid space of the spinal cord after gas contrasting. It is used to diagnose pathological processes in the area of the spinal canal, causing narrowing of its lumen (herniated discs, tumors). Rarely used.

Pneumoencephalography- X-ray examination of the cerebrospinal fluid spaces of the brain after contrasting with gas. Once introduced into clinical practice, CT and MRI are rarely performed.

Pneumoarthrography- X-ray examination of large joints after the introduction of gas into their cavity. Allows you to study the articular cavity, identify intra-articular bodies in it, detect signs of damage to the menisci of the knee joint. Sometimes it is supplemented by the introduction into the joint cavity

water-soluble RCS. It is widely used in medical institutions when it is impossible to perform MRI.

Bronchography- a technique for X-ray examination of the bronchi after their artificial contrasting of the RCS. Allows you to identify various pathological changes in the bronchi. It is widely used in medical institutions when CT is not available.

Pleurography- X-ray examination of the pleural cavity after its partial filling with a contrast agent in order to clarify the shape and size of pleural encystation.

Sinography- X-ray examination of the paranasal sinuses after their filling with the RCS. It is used when there are difficulties in interpreting the cause of shading of the sinuses on radiographs.

Dacryocystography- X-ray examination of the lacrimal ducts after their filling with the RCS. It is used to study the morphological state of the lacrimal sac and the patency of the lacrimal canal.

Sialography- X-ray examination of the ducts of the salivary glands after their filling with the RCS. It is used to assess the condition of the ducts of the salivary glands.

X-ray of the esophagus, stomach and duodenum- is carried out after their gradual filling with a suspension of barium sulfate, and, if necessary, with air. It necessarily includes polypositional fluoroscopy and the performance of survey and sighting radiographs. It is widely used in medical institutions to detect various diseases of the esophagus, stomach and duodenum (inflammatory and destructive changes, tumors, etc.) (see Fig. 2.14).

Enterography- X-ray examination of the small intestine after filling its loops with a suspension of barium sulfate. Allows you to get information about the morphological and functional state of the small intestine (see Fig. 2.15).

Irrigoscopy- X-ray examination of the colon after retrograde contrasting of its lumen with a suspension of barium sulfate and air. It is widely used to diagnose many diseases of the colon (tumors, chronic colitis, etc.) (see Fig. 2.16).

Cholecystography- X-ray examination of the gallbladder after the accumulation of a contrast agent in it, taken orally and excreted with bile.

Excretory cholegraphy- X-ray examination of the biliary tract, contrasted with iodine-containing drugs administered intravenously and excreted in the bile.

Cholangiography- X-ray examination of the bile ducts after the introduction of the RCS into their lumen. It is widely used to clarify the morphological state of the bile ducts and to identify stones in them. It can be performed during surgery (intraoperative cholangiography) and in the postoperative period (through a drainage tube) (see Fig. 2.17).

Retrograde cholangiopancreaticography- X-ray examination of the bile ducts and pancreatic duct after injection

into their lumen of a contrast agent under X-ray endoscopic control (see Fig. 2.18).

Rice. 2.14. X-ray of the stomach, contrasted with a suspension of barium sulfate. Norm

Rice. 2.16. Irrigogram. Colon cancer. The lumen of the caecum is sharply narrowed, the contours of the affected area are uneven (indicated by arrows in the picture)

Rice. 2.15. X-ray of the small intestine, contrasted with a suspension of barium sulfate (enterogram). Norm

Rice. 2.17. Antegrade cholangiogram. Norm

Excretory urography- X-ray examination of the urinary organs after intravenous administration of RCS and its excretion by the kidneys. A widely used research technique that allows you to study the morphological and functional state of the kidneys, ureters and bladder (see Fig. 2.19).

Retrograde ureteropyelography- X-ray examination of the ureters and cavitary systems of the kidneys after filling them with RCS through a ureteral catheter. Compared with excretory urography, it provides more complete information about the state of the urinary tract

as a result of their better filling with a contrast agent injected under low pressure. Widely used in specialized urological departments.

Rice. 2.18. Retrograde cholangiopancreaticogram. Norm

Rice. 2.19. Excretory urogram. Norm

Cystography- X-ray examination of the bladder filled with RCS (see Fig. 2.20).

urethrography- X-ray examination of the urethra after its filling with the RCS. Allows you to get information about the patency and morphological state of the urethra, identify its damage, strictures, etc. It is used in specialized urological departments.

Hysterosalpingography- X-ray examination of the uterus and fallopian tubes after filling their lumen with the RCS. It is widely used primarily to assess the patency of the fallopian tubes.

Positive myelography- X-ray examination of the subarachnoid spaces of the spinal

Rice. 2.20. Descending cystogram. Norm

brain after administration of water-soluble RCS. With the advent of MRI, it is rarely used.

Aortography- X-ray examination of the aorta after the introduction of the RCS into its lumen.

Arteriography- X-ray examination of the arteries with the help of RCS introduced into their lumen, spreading through the blood flow. Some private methods of arteriography (coronary angiography, carotid angiography), being highly informative, are at the same time technically complex and unsafe for the patient, and therefore are used only in specialized departments (Fig. 2.21).

Rice. 2.21. Carotid angiograms in direct (a) and lateral (b) projections. Norm

Cardiography- X-ray examination of the cavities of the heart after the introduction of the RCS into them. Currently, it finds limited use in specialized cardiac surgery hospitals.

Angiopulmonography- X-ray examination of the pulmonary artery and its branches after the introduction of RCS into them. Despite the high information content, it is unsafe for the patient, and therefore, in recent years, preference has been given to computed tomographic angiography.

Phlebography- X-ray examination of the veins after the introduction of the RCS into their lumen.

Lymphography- X-ray examination of the lymphatic tract after the introduction of the RCS into the lymphatic channel.

Fistulography- X-ray examination of the fistulous tracts after their filling by the RCS.

Vulnerography- X-ray examination of the wound channel after filling it with RCS. It is more often used for blind wounds of the abdomen, when other research methods do not allow to establish whether the wound is penetrating or non-penetrating.

Cystography- contrast x-ray examination of cysts of various organs in order to clarify the shape and size of the cyst, its topographic location and the state of the inner surface.

Ductography- contrast x-ray examination of the milk ducts. Allows you to assess the morphological state of the ducts and identify small breast tumors with intraductal growth, indistinguishable on mammograms.

INDICATIONS FOR THE USE OF THE RADIOLOGICAL METHOD

Head

1. Anomalies and malformations of the bone structures of the head.

2. Head injury:

Diagnosis of fractures of the bones of the brain and facial parts of the skull;

Identification of foreign bodies of the head.

3. Brain tumors:

Diagnosis of pathological calcifications characteristic of tumors;

Identification of the tumor vasculature;

Diagnosis of secondary hypertensive-hydrocephalic changes.

4. Diseases of the vessels of the brain:

Diagnosis of aneurysms and vascular malformations (arterial aneurysms, arterio-venous malformations, arterio-sinus anastomoses, etc.);

Diagnosis of stenosing and occlusive diseases of the vessels of the brain and neck (stenosis, thrombosis, etc.).

5. Diseases of the ENT organs and the organ of vision:

Diagnosis of tumor and non-tumor diseases.

6. Diseases of the temporal bone:

Diagnosis of acute and chronic mastoiditis.

Breast

1. Chest injury:

Diagnosis of chest injuries;

Identification of fluid, air or blood in the pleural cavity (pneumo-, hemothorax);

Identification of pulmonary contusions;

Detection of foreign bodies.

2. Tumors of the lungs and mediastinum:

Diagnosis and differential diagnosis of benign and malignant tumors;

Assessment of the state of regional lymph nodes.

3. Tuberculosis:

Diagnosis of various forms of tuberculosis;

Assessment of the state of intrathoracic lymph nodes;

Differential diagnosis with other diseases;

Evaluation of the effectiveness of treatment.

4. Diseases of the pleura, lungs and mediastinum:

Diagnosis of all forms of pneumonia;

Diagnosis of pleurisy, mediastinitis;

Diagnosis of pulmonary embolism;

Diagnosis of pulmonary edema;

5. Examination of the heart and aorta:

Diagnosis of acquired and congenital malformations of the heart and aorta;

Diagnosis of heart damage in case of chest and aortic injury;

Diagnosis of various forms of pericarditis;

Assessment of the state of coronary blood flow (coronary angiography);

Diagnosis of aortic aneurysms.

Stomach

1. Abdominal injury:

Identification of free gas and liquid in the abdominal cavity;

Detection of foreign bodies;

Establishment of the penetrating nature of the abdominal wound.

2. Examination of the esophagus:

Diagnosis of tumors;

Detection of foreign bodies.

3. Examination of the stomach:

Diagnosis of inflammatory diseases;

Diagnosis of peptic ulcer;

Diagnosis of tumors;

Detection of foreign bodies.

4. Intestinal examination:

Diagnosis of intestinal obstruction;

Diagnosis of tumors;

Diagnosis of inflammatory diseases.

5. Examination of the urinary organs:

Identification of anomalies and development options;

Urolithiasis disease;

Identification of stenotic and occlusive diseases of the renal arteries (angiography);

Diagnosis of stenotic diseases of the ureters, urethra;

Diagnosis of tumors;

Detection of foreign bodies;

Assessment of excretory function of the kidneys;

Monitoring the effectiveness of the treatment.

Taz

1. Injury:

Diagnosis of pelvic fractures;

Diagnosis of ruptures of the bladder, posterior urethra and rectum.

2. Congenital and acquired deformities of the pelvic bones.

3. Primary and secondary tumors of the pelvic bones and pelvic organs.

4. Sacroiliitis.

5. Diseases of the female genital organs:

Evaluation of the patency of the fallopian tubes.

Spine

1. Anomalies and malformations of the spine.

2. Injury of the spine and spinal cord:

Diagnosis of various types of fractures and dislocations of the vertebrae.

3. Congenital and acquired spinal deformities.

4. Tumors of the spine and spinal cord:

Diagnosis of primary and metastatic tumors of bone structures of the spine;

Diagnosis of extramedullary tumors of the spinal cord.

5. Degenerative-dystrophic changes:

Diagnosis of spondylosis, spondylarthrosis and osteochondrosis and their complications;

Diagnosis of herniated discs;

Diagnosis of functional instability and functional block of the vertebrae.

6. Inflammatory diseases of the spine (specific and nonspecific spondylitis).

7. Osteochondropathy, fibrous osteodystrophy.

8. Densitometry in systemic osteoporosis.

limbs

1. Injuries:

Diagnosis of fractures and dislocations of limbs;

Monitoring the effectiveness of the treatment.

2. Congenital and acquired limb deformities.

3. Osteochondropathy, fibrous osteodystrophy; congenital systemic diseases of the skeleton.

4. Diagnosis of tumors of bones and soft tissues of the extremities.

5. Inflammatory diseases of bones and joints.

6. Degenerative-dystrophic diseases of the joints.

7. Chronic diseases of the joints.

8. Stenosing and occlusive diseases of the vessels of the extremities.

X-ray methods of research

1. The concept of X-rays

X-rays are called electromagnetic waves with a length of approximately 80 to 10 ~ 5 nm. The longest-wavelength X-rays are covered by short-wavelength ultraviolet radiation, and the short-wavelength ones by long-wavelength Y-radiation. According to the method of excitation, X-ray radiation is divided into bremsstrahlung and characteristic.

The most common X-ray source is the X-ray tube, which is a two-electrode vacuum device. The heated cathode emits electrons. The anode, often called the anticathode, has an inclined surface in order to direct the resulting X-ray radiation at an angle to the axis of the tube. The anode is made of a highly heat-conducting material to remove the heat generated by the impact of electrons. The anode surface is made of refractory materials having a large atomic number in the periodic table, such as tungsten. In some cases, the anode is specially cooled with water or oil.

For diagnostic tubes, the pinpointness of the X-ray source is important, which can be achieved by focusing electrons in one place of the anticathode. Therefore, constructively, two opposite tasks have to be taken into account: on the one hand, electrons must fall on one place of the anode, on the other hand, in order to prevent overheating, it is desirable to distribute electrons over different parts of the anode. One of the interesting technical solutions is an X-ray tube with a rotating anode. As a result of deceleration of an electron (or other charged particle) by the electrostatic field of the atomic nucleus and atomic electrons of the anti-cathode substance, bremsstrahlung X-ray radiation occurs. Its mechanism can be explained as follows. A moving electric charge is associated with a magnetic field, the induction of which depends on the speed of the electron. When braking, the magnetic induction decreases and, in accordance with Maxwell's theory, an electromagnetic wave appears.

When electrons decelerate, only part of the energy goes to create an X-ray photon, the other part is spent on heating the anode. Since the ratio between these parts is random, when a large number of electrons decelerate, a continuous spectrum of X-ray radiation is formed. In this regard, bremsstrahlung is also called continuous.

In each of the spectra, the shortest wavelength bremsstrahlung occurs when the energy acquired by an electron in the accelerating field is completely converted into the energy of a photon.

Short-wavelength X-rays usually have a greater penetrating power than long-wavelength ones and are called hard, while long-wavelength ones are called soft. Increasing the voltage on the x-ray tube, change the spectral composition of the radiation. If the cathode filament temperature is increased, then the electron emission and the current in the tube will increase. This will increase the number of X-ray photons emitted every second. Its spectral composition will not change. By increasing the voltage on the X-ray tube, one can notice the appearance of a line, which corresponds to the characteristic X-ray radiation, against the background of a continuous spectrum. It arises due to the fact that accelerated electrons penetrate deep into the atom and knock electrons out of the inner layers. Electrons from the upper levels pass to free places, as a result, photons of characteristic radiation are emitted. In contrast to optical spectra, the characteristic x-ray spectra of different atoms are of the same type. The uniformity of these spectra is due to the fact that the inner layers of different atoms are the same and differ only energetically, since the force effect from the nucleus increases with the increase in the ordinal number of the element. This circumstance leads to the fact that the characteristic spectra shift towards higher frequencies with increasing nuclear charge. This pattern is known as Moseley's law.

There is another difference between optical and x-ray spectra. The characteristic X-ray spectrum of an atom does not depend on the chemical compound in which this atom is included. So, for example, the X-ray spectrum of the oxygen atom is the same for O, O 2 and H 2 O, while the optical spectra of these compounds are significantly different. This feature of the X-ray spectrum of an atom served as the basis for the name characteristic.

characteristic Radiation always occurs when there is free space in the inner layers of an atom, regardless of the reason that caused it. So, for example, characteristic radiation accompanies one of the types of radioactive decay, which consists in the capture of an electron from the inner layer by the nucleus.

Registration and use of X-ray radiation, as well as its impact on biological objects, are determined by the primary processes of interaction of an X-ray photon with electrons of atoms and molecules of a substance.

Depending on the ratio of photon energy and ionization energy, three main processes take place

Coherent (classical) scattering. Scattering of long-wavelength X-rays occurs mainly without changing the wavelength, and it is called coherent. It occurs when the photon energy is less than the ionization energy. Since in this case the energy of the X-ray photon and the atom does not change, coherent scattering in itself does not cause a biological effect. However, when creating protection against X-ray radiation, one should take into account the possibility of changing the direction of the primary beam. This type of interaction is important for X-ray diffraction analysis.

Incoherent scattering (Compton effect). In 1922 A.Kh. Compton, observing the scattering of hard X-rays, discovered a decrease in the penetrating power of the scattered beam compared to the incident beam. This meant that the wavelength of the scattered X-rays was greater than that of the incident X-rays. The scattering of X-rays with a change in wavelength is called incoherent, and the phenomenon itself is called the Compton effect. It occurs if the energy of the X-ray photon is greater than the ionization energy. This phenomenon is due to the fact that when interacting with an atom, the energy of a photon is spent on the formation of a new scattered X-ray photon, on detaching an electron from an atom (ionization energy A) and imparting kinetic energy to an electron.

It is significant that in this phenomenon, along with secondary X-ray radiation (energy hv "of a photon), recoil electrons appear (kinetic energy £k of an electron). In this case, atoms or molecules become ions.

Photoelectric effect. In the photoelectric effect, X-ray radiation is absorbed by an atom, as a result of which an electron flies out, and the atom is ionized (photoionization). If the photon energy is insufficient for ionization, then the photoelectric effect can manifest itself in the excitation of atoms without the emission of electrons.

Let us list some of the processes observed under the action of X-rays on matter.

X-ray luminescence- the glow of a number of substances under X-ray irradiation. Such a glow of platinum-cyanogen barium allowed Roentgen to discover the rays. This phenomenon is used to create special luminous screens for the purpose of visual observation of x-rays, sometimes to enhance the action of x-rays on a photographic plate.

Known chemical action x-rays, such as the formation of hydrogen peroxide in water. A practically important example is the effect on a photographic plate, which makes it possible to detect such rays.

Ionizing action manifests itself in an increase in electrical conductivity under the influence of x-rays. This property is used in dosimetry to quantify the effect of this type of radiation.

One of the most important medical applications of X-rays is the transillumination of internal organs for diagnostic purposes (X-ray diagnostics).

X-ray method is a method of studying the structure and function of various organs and systems, based on a qualitative and / or quantitative analysis of an X-ray beam that has passed through the human body. The X-ray radiation that has arisen in the anode of the X-ray tube is directed to the patient, in whose body it is partially absorbed and scattered, and partially passes through. The image converter sensor captures the transmitted radiation, and the converter builds a visible light image that the doctor perceives.

A typical x-ray diagnostic system consists of an x-ray emitter (tube), an object of study (patient), an image converter and a radiologist.

For diagnostics, photons with an energy of about 60-120 keV are used. At this energy, the mass extinction coefficient is mainly determined by the photoelectric effect. Its value is inversely proportional to the third power of the photon energy (proportional to X 3), which manifests a large penetrating power of hard radiation and is proportional to the third power of the atomic number of the absorbing substance. The absorption of x-rays is almost independent of which compound the atom is in the substance, so one can easily compare the mass attenuation coefficients of bone, soft tissue, or water. A significant difference in the absorption of x-ray radiation by different tissues allows you to see images of the internal organs of the human body in a shadow projection.

A modern X-ray diagnostic unit is a complex technical device. It is saturated with elements of teleautomatics, electronics, electronic computers. A multi-stage protection system ensures radiation and electrical safety of personnel and patients.

It is customary to divide X-ray diagnostic devices into universal ones, which allow X-ray translucence and X-ray images of all parts of the body, and special-purpose devices. The latter are designed to perform x-ray studies in neurology, maxillofacial surgery and dentistry, mammology, urology, angiology. Special devices have also been created for examining children, for mass screening studies (fluorographs), for studies in operating rooms. For roentgenoscopy and radiography of patients in the wards and intensive care unit, mobile x-ray units are used.

A typical X-ray diagnostic apparatus includes a power supply, a control panel, a tripod and an X-ray tube. She, in fact, is the source of radiation. The unit is powered from the mains in the form of low voltage alternating current. In a high-voltage transformer, the mains current is converted into high-voltage alternating current. The stronger the radiation absorbed by the organ under study, the more intense the shadow that it casts on the X-ray fluorescent screen. Conversely, the more rays pass through the organ, the weaker its shadow on the screen.

In order to obtain a differentiated image of tissues that absorb radiation approximately equally, artificial contrasting is used. For this purpose, substances are introduced into the body that absorb X-rays more strongly or, conversely, weaker than soft tissues, and thereby create a sufficient contrast with respect to the organs under study. Substances that delay radiation more strongly than soft tissues are called X-ray positive. They are created on the basis of heavy elements - barium or iodine. As X-ray negative substances, gases are used: nitrous oxide, carbon dioxide, oxygen, air. The main requirements for radiopaque substances are obvious: their maximum harmlessness (low toxicity), rapid excretion from the body.

There are two fundamentally different ways of contrasting organs. One of them is the direct (mechanical) injection of a contrast agent into the organ cavity - into the esophagus, stomach, intestines, into the lacrimal or salivary ducts, bile ducts, urinary tract, into the uterine cavity, bronchi, blood and lymphatic vessels. In other cases, a contrast agent is injected into the cavity or cellular space surrounding the organ under study (for example, into the retroperitoneal tissue surrounding the kidneys and adrenal glands), or by puncture into the parenchyma of the organ.

The second method of contrasting is based on the ability of some organs to absorb a substance introduced into the body from the blood, concentrate and release it. This principle - concentration and elimination - is used in X-ray contrasting of the excretory system and biliary tract.

In some cases, x-ray examination is carried out simultaneously with two radiopaque agents. Most often, this technique is used in gastroenterology, producing the so-called double contrasting of the stomach or intestines: an aqueous suspension of barium sulfate and air are introduced into the studied part of the digestive canal.

There are 5 types of X-ray receivers: X-ray film, semiconductor photosensitive plate, fluorescent screen, X-ray image intensifier tube, dosimetric counter. Accordingly, 5 general methods of X-ray examination are built on them: radiography, electroroentgenography, fluoroscopy, X-ray television fluoroscopy and digital radiography (including computed tomography).

2. Radiography (X-ray photography)

Radiography- a method of x-ray examination, in which the image of the object is obtained on x-ray film by direct exposure to a radiation beam.

Film radiography is performed either on a universal X-ray machine or on a special tripod designed only for shooting. The patient is positioned between the x-ray tube and the film. The part of the body to be examined is brought as close as possible to the cassette. This is necessary to avoid significant magnification of the image due to the divergent nature of the X-ray beam. In addition, it provides the necessary image sharpness. The X-ray tube is installed in such a position that the central beam passes through the center of the part of the body being removed and perpendicular to the film. The part of the body to be examined is exposed and fixed with special devices. All other parts of the body are covered with protective screens (eg, lead rubber) to reduce radiation exposure. Radiography can be performed in the vertical, horizontal and inclined position of the patient, as well as in the position on the side. Shooting in different positions allows you to judge the displacement of organs and identify some important diagnostic features, such as fluid spreading in the pleural cavity or fluid levels in intestinal loops.

An image that shows a part of the body (head, pelvis, etc.) or the entire organ (lungs, stomach) is called an overview. Pictures on which an image of the part of the organ of interest to the doctor is obtained in the optimal projection, the most beneficial for the study of one or another detail, are called sighting. They are often produced by the doctor himself under the control of translucence. Snapshots can be single or burst. A series may consist of 2-3 radiographs, on which various states of the organ are recorded (for example, gastric peristalsis). But more often, serial radiography is understood as the production of several radiographs during one examination and usually in a short period of time. For example, with arteriography, up to 6-8 pictures per second are produced using a special device - a seriograph.

Among the options for radiography, shooting with direct magnification of the image deserves mention. Magnifications are achieved by moving the X-ray cassette away from the subject. As a result, an image of small details that are indistinguishable in ordinary photographs is obtained on the radiograph. This technology can only be used with special X-ray tubes with very small focal spot sizes - about 0.1 - 0.3 mm 2 . To study the osteoarticular system, an image magnification of 5-7 times is considered optimal.

X-rays can show any part of the body. Some organs are clearly visible in the images due to natural contrast conditions (bones, heart, lungs). Other organs are clearly displayed only after their artificial contrasting (bronchi, blood vessels, heart cavities, bile ducts, stomach, intestines, etc.). In any case, the x-ray picture is formed from light and dark areas. The blackening of x-ray film, like photographic film, occurs due to the reduction of metallic silver in its exposed emulsion layer. To do this, the film is subjected to chemical and physical processing: it is developed, fixed, washed and dried. In modern X-ray rooms, the entire process is fully automated due to the presence of processors. The use of microprocessor technology, high temperature and high-speed reagents can reduce the time for obtaining x-rays to 1-1.5 minutes.

It should be remembered that an X-ray image in relation to the image visible on a fluorescent screen during transmission is a negative. Therefore, transparent areas on the x-ray are called dark (“blackouts”), and dark areas are called light (“enlightenments”). But the main feature of the radiograph is different. Each beam on its way through the human body crosses not one, but a huge number of points located both on the surface and in the depths of tissues. Therefore, each point on the image corresponds to a set of real points of the object, which are projected onto each other. The x-ray image is summation, planar. This circumstance leads to the loss of the image of many elements of the object, since the image of some details is superimposed on the shadow of others. This implies the basic rule of X-ray examination: the examination of any part of the body (organ) must be carried out in at least two mutually perpendicular projections - direct and lateral. In addition to them, images in oblique and axial (axial) projections may be needed.

Radiographs are studied in accordance with the general scheme for the analysis of beam images.

The method of radiography is used everywhere. It is available to all medical institutions, simple and easy for the patient. Pictures can be taken in a stationary X-ray room, in the ward, in the operating room, in the intensive care unit. With the correct choice of technical conditions, fine anatomical details are displayed in the image. A radiograph is a document that can be stored for a long time, used for comparison with repeated radiographs and presented for discussion to an unlimited number of specialists.

Indications for radiography are very wide, but in each individual case they must be justified, since X-ray examination is associated with radiation exposure. Relative contraindications are an extremely severe or highly agitated condition of the patient, as well as acute conditions requiring emergency surgical care (for example, bleeding from a large vessel, open pneumothorax).

3. Electroradiography

Electroradiography- a method of obtaining an x-ray image on semiconductor wafers with its subsequent transfer to paper.

The electro-radiographic process includes the following steps: plate charging, exposure, development, image transfer, image fixation.

Plate charging. A metal plate coated with a selenium semiconductor layer is placed in the charger of the electroroentgenograph. In it, an electrostatic charge is imparted to the semiconductor layer, which can be maintained for 10 minutes.

Exposure. X-ray examination is carried out in the same way as in conventional radiography, only a plate cassette is used instead of a film cassette. Under the influence of X-ray irradiation, the resistance of the semiconductor layer decreases, it partially loses its charge. But in different places of the plate, the charge does not change in the same way, but in proportion to the number of X-ray quanta falling on them. A latent electrostatic image is created on the plate.

Manifestation. An electrostatic image is developed by spraying a dark powder (toner) onto the plate. Negatively charged powder particles are attracted to those areas of the selenium layer that have retained a positive charge, and to a degree proportional to the charge.

Transferring and fixing the image. In an electroretinograph, the image from the plate is transferred by a corona discharge to paper (writing paper is most often used) and fixed in a pair of fixer. The plate after cleaning from the powder is again suitable for consumption.

The electroradiographic image differs from the film image in two main features. The first is its large photographic latitude - both dense formations, in particular bones, and soft tissues are well displayed on the electroroentgenogram. With film radiography, this is much more difficult to achieve. The second feature is the phenomenon of contour underlining. On the border of fabrics of different density, they seem to be painted on.

The positive aspects of electroroentgenography are: 1) cost-effectiveness (cheap paper, for 1000 or more shots); 2) the speed of obtaining an image - only 2.5-3 minutes; 3) all research is carried out in a darkened room; 4) the “dry” nature of image acquisition (that is why, abroad, electroradiography is called xeroradiography - from the Greek xeros - dry); 5) storage of electroroentgenograms is much easier than that of x-ray films.

At the same time, it should be noted that the sensitivity of the electro-radiographic plate is significantly (1.5-2 times) inferior to the sensitivity of the film-intensifying screen combination used in conventional radiography. Therefore, when shooting, it is necessary to increase the exposure, which is accompanied by an increase in radiation exposure. Therefore, electroradiography is not used in pediatric practice. In addition, artifacts (spots, stripes) quite often appear on electroroentgenograms. With this in mind, the main indication for its use is an urgent x-ray examination of the extremities.

Fluoroscopy (X-ray transillumination)

Fluoroscopy- a method of X-ray examination, in which an image of an object is obtained on a luminous (fluorescent) screen. The screen is cardboard coated with a special chemical composition. This composition under the influence of x-rays begins to glow. The intensity of the glow at each point of the screen is proportional to the number of X-ray quanta that fell on it. On the side facing the doctor, the screen is covered with lead glass, which protects the doctor from direct exposure to x-rays.

The fluorescent screen glows faintly. Therefore, fluoroscopy is performed in a darkened room. The doctor must get used (adapt) to the darkness within 10-15 minutes in order to distinguish a low-intensity image. The retina of the human eye contains two types of visual cells - cones and rods. The cones are responsible for the perception of color images, while the rods are the mechanism for dim vision. It can be figuratively said that a radiologist with normal transillumination works with “sticks”.

Radioscopy has many advantages. It is easy to implement, publicly available, economical. It can be performed in the X-ray room, in the dressing room, in the ward (using a mobile X-ray machine). Fluoroscopy allows you to study the movement of organs with a change in body position, contraction and relaxation of the heart and pulsation of blood vessels, respiratory movements of the diaphragm, peristalsis of the stomach and intestines. Each organ is easy to examine in different projections, from all sides. Radiologists call this method of research multi-axis, or the method of rotating the patient behind the screen. Fluoroscopy is used to select the best projection for radiography in order to perform so-called sightings.

However, conventional fluoroscopy has its weaknesses. It is associated with a higher radiation exposure than radiography. It requires darkening of the office and careful dark adaptation of the doctor. After it, there is no document (snapshot) left that could be stored and would be suitable for re-consideration. But the most important thing is different: on the screen for transmission, small details of the image cannot be distinguished. This is not surprising: take into account that the brightness of a good negatoscope is 30,000 times greater than that of a fluorescent screen during fluoroscopy. Due to the high radiation exposure and low resolution, fluoroscopy is not allowed to be used for screening studies of healthy people.

All the noted shortcomings of conventional fluoroscopy are eliminated to a certain extent if an X-ray image intensifier (ARI) is introduced into the X-ray diagnostic system. Flat URI type "Cruise" increases the brightness of the screen by 100 times. And URI, which includes a television system, provides amplification by several thousand times and makes it possible to replace conventional fluoroscopy with X-ray television transmission.

4. X-ray television transillumination

X-ray television transillumination is a modern type of fluoroscopy. It is performed using an X-ray image intensifier (ARI), which includes an X-ray image intensifier tube (REOP) and a closed-circuit television system.

REOP is a vacuum flask, inside which, on the one hand, there is an X-ray fluorescent screen, and on the opposite side, a cathodoluminescent screen. An electric accelerating field with a potential difference of about 25 kV is applied between them. The light image that arises during transmission on a fluorescent screen is converted on a photocathode into a stream of electrons. Under the action of the accelerating field and as a result of focusing (increasing the flux density), the energy of electrons increases significantly - several thousand times. Getting on the cathodoluminescent screen, the electron flow creates a visible image on it, similar to the original, but very bright image.

This image is transmitted through a system of mirrors and lenses to a transmitting television tube - a vidicon. The electrical signals arising in it are fed for processing to the television channel unit, and then to the screen of the video control device or, more simply, to the TV screen. If necessary, the image can be recorded using a video recorder.

Thus, in the URI, the following chain of transformation of the image of the object under study is carried out: X-ray - light - electronic (at this stage, the signal is amplified) - again light - electronic (here it is possible to correct some characteristics of the image) - again light.

An x-ray image on a television screen, like a conventional television image, can be viewed in visible light. Thanks to URI, radiologists have made the leap from the realm of darkness to the realm of light. As one scientist wittily remarked, "the dark past of radiology is over." But for many decades, radiologists could take the words inscribed on the emblem of Don Quixote as their slogan: “Postnebrassperolucem” (“After darkness, I hope for light”).

X-ray television transillumination does not require dark adaptation of the doctor. Radiation load on the staff and the patient with it is much less than with conventional fluoroscopy. On the TV screen, details are visible that are not captured by fluoroscopy. The X-ray image can be transmitted via the television path to other monitors (to the control room, to the classroom, to the consultant's office, etc.). Television equipment provides the possibility of video recording of all stages of the study.

With the help of mirrors and lenses, the x-ray image from the x-ray image intensifier tube can be entered into the movie camera. This X-ray examination is called X-ray cinematography. This image can also be sent to the camera. The resulting images, which have small - 70X70 or 100X 100 mm - dimensions and are made on X-ray film, are called photoroentgenograms (URI-fluorograms). They are more economical than conventional radiographs. In addition, when they are performed, the radiation load on the patient is less. Another advantage is the possibility of high-speed shooting - up to 6 frames per second.

5. Fluorography

Fluorography - method of X-ray examination, which consists in photographing an image from an X-ray fluorescent screen or the screen of an electron-optical converter onto a small format photographic film.

With the most common method of fluorography, reduced x-rays - fluorograms are obtained on a special x-ray machine - a fluorograph. This machine has a fluorescent screen and an automatic roll film transfer mechanism. Photographing the image is carried out by means of a camera on this roll film with a frame size of 70X70 or 100X100 mm.

With another method of fluorography, already mentioned in the previous paragraph, photographs are taken on films of the same format directly from the screen of the electron-optical converter. This research method is called URI-fluorography. The technique is especially beneficial in the study of the esophagus, stomach and intestines, as it provides a quick transition from transillumination to imaging.

On fluorograms, image details are fixed better than with fluoroscopy or X-ray television transillumination, but somewhat worse (by 4-5%) compared to conventional radiographs. In polyclinics and hospitals, more expensive radiography, especially with repeated control studies. This x-ray examination is called diagnostic fluorography. The main purpose of fluorography in our country is to conduct mass screening x-ray studies, mainly to detect latent lung lesions. Such fluorography is called verification or prophylactic. It is a method of selection from a population of persons with suspected disease, as well as a method of dispensary observation of people with inactive and residual tuberculous changes in the lungs, pneumosclerosis, etc.

For verification studies, stationary and mobile type fluorographs are used. The former are placed in polyclinics, medical units, dispensaries, and hospitals. Mobile fluorographs are mounted on automobile chassis or in railway cars. Shooting in both fluorographs is carried out on a roll film, which is then developed in special tanks. Due to the small frame format, fluorography is much cheaper than radiography. Its widespread use means significant cost savings for the medical service. To study the esophagus, stomach and duodenum, special gastrofluorographs have been created.

Ready fluorograms are examined on a special flashlight - a fluoroscope, which magnifies the image. From the general contingent of the examined persons are selected, in whom pathological changes are suspected according to fluorograms. They are sent for an additional examination, which is carried out on x-ray diagnostic units using all the necessary x-ray methods.

Important advantages of fluorography are the ability to examine a large number of people in a short time (high throughput), cost-effectiveness, and ease of storage of fluorograms. Comparison of fluorograms made during the next check-up examination with fluorograms of previous years allows early detection of minimal pathological changes in organs. This technique is called retrospective analysis of fluorograms.

The most effective was the use of fluorography to detect latent lung diseases, primarily tuberculosis and cancer. The frequency of screening examinations is determined taking into account the age of people, the nature of their work, local epidemiological conditions.

6. Digital (digital) radiography

The x-ray imaging systems described above are referred to as conventional or conventional radiology. But in the family of these systems, a new child is rapidly growing and developing. These are digital (digital) methods of obtaining images (from the English digit - figure). In all digital devices, the image is constructed in principle the same way. Each "digital" picture consists of many individual dots. Each point of the image is assigned a number that corresponds to the intensity of its glow (its "greyness"). The degree of brightness of a point is determined in a special device - an analog-to-digital converter (ADC). As a rule, the number of pixels in one row is 32, 64, 128, 256, 512 or 1024, and their number is equal in the width and height of the matrix. With a matrix size of 512 X 512, the digital image consists of 262,144 individual dots.

The X-ray image obtained in the television camera is received after conversion in the amplifier to the ADC. In it, the electrical signal carrying information about the x-ray image is converted into a series of numbers. Thus, a digital image is created - digital encoding of signals. Digital information then enters the computer, where it is processed according to pre-compiled programs. The program is chosen by the doctor, based on the objectives of the study. When converting an analog image into a digital image, there is, of course, some loss of information. But it is compensated by the possibilities of computer processing. With the help of a computer, you can improve the quality of the image: increase its contrast, clear it of interference, highlight details or contours that are of interest to the doctor. For example, the Polytron device created by Siemens with a 1024 X 1024 matrix allows achieving a signal-to-noise ratio of 6000:1. This ensures not only radiography but also fluoroscopy with high image quality. In a computer, you can add images or subtract one from another.

To turn digital information into an image on a television screen or film, you need a digital-to-analog converter (DAC). Its function is the opposite of ADC. It transforms a digital image "hidden" in a computer into an analog, visible one (performs decoding).

Digital radiography has a great future. There is reason to believe that it will gradually replace conventional radiography. It does not require expensive x-ray film and photoprocess, it is fast. It allows, after the end of the study, to perform further (a posteriori) processing of the image and its transmission over a distance. It is very convenient to store information on magnetic media (discs, tapes).

Of great interest is digital fluorescent radiography based on the use of a fluorescent screen image memory. During an x-ray exposure, an image is recorded on such a plate and then read from it using a helium-neon laser and recorded in digital form. Radiation exposure compared to conventional radiography is reduced by 10 or more times. Other methods of digital radiography are also being developed (for example, the removal of electrical signals from an exposed selenium plate without processing it in an electroroentgenograph).

Basic methods of X-ray examination

Classification of methods of X-ray examination

X-ray techniques

Basic Methods	Additional Methods	Special methods - additional contrast is needed
Radiography	Linear tomography	X-ray negative substances (gases)
Fluoroscopy	Sonography	X-ray positive substances	Heavy metal salts (barium oxide sulfac)
Fluorography	Kymography	Iodine-containing water-soluble substances
Electro-radiography	Electrokymography	ionic
	Stereo X-ray	non-ionic
	X-ray cinematography	Iodine-containing fat-soluble substances
	CT scan	Tropic action of the substance.
	MRI

Radiography is a method of X-ray examination, in which an image of an object is obtained on an X-ray film by direct exposure to a radiation beam.

Among the options for radiography, shooting with direct magnification of the image deserves mention. Magnifications are achieved by moving the X-ray cassette away from the subject. As a result, an image of small details that are indistinguishable in ordinary photographs is obtained on the radiograph. This technology can only be used with special X-ray tubes with very small focal spot sizes - about 0.1 - 0.3 mm2. To study the osteoarticular system, an image magnification of 5-7 times is considered optimal.

Radiographs are studied in accordance with the general scheme for the analysis of beam images.

Benefits of radiography

1. Wide availability of the method and ease of research.

2. Most studies do not require special patient preparation.

3. Relatively low cost of research.

4. The images can be used for consultation with another specialist or in another institution (unlike ultrasound images, where a second examination is necessary, since the images obtained are operator-dependent).

Disadvantages of radiography

1. "Freezing" of the image - the complexity of assessing the function of an organ.

2. The presence of ionizing radiation that can have a harmful effect on the organism under study.

3. The information content of classical radiography is much lower than such modern methods of medical imaging as CT, MRI, etc. Conventional X-ray images reflect the projection layering of complex anatomical structures, that is, their summation X-ray shadow, in contrast to the layered series of images obtained by modern tomographic methods.

4. Without the use of contrast agents, radiography is practically uninformative for the analysis of changes in soft tissues.

Electroradiography is a method of obtaining an x-ray image on semiconductor wafers and then transferring it to paper.

The electro-radiographic process includes the following steps: plate charging, exposure, development, image transfer, image fixation.

Plate charging. A metal plate coated with a selenium semiconductor layer is placed in the charger of the electroroentgenograph. In it, an electrostatic charge is imparted to the semiconductor layer, which can be maintained for 10 minutes.

Exposure. X-ray examination is carried out in the same way as in conventional radiography, only a plate cassette is used instead of a film cassette. Under the influence of X-ray irradiation, the resistance of the semiconductor layer decreases, it partially loses its charge. But in different places of the plate, the charge does not change in the same way, but in proportion to the number of X-ray quanta falling on them. A latent electrostatic image is created on the plate.

Manifestation. An electrostatic image is developed by spraying a dark powder (toner) onto the plate. Negatively charged powder particles are attracted to those areas of the selenium layer that have retained a positive charge, and to a degree proportional to the charge.

Transferring and fixing the image. In an electroretinograph, the image from the plate is transferred by a corona discharge to paper (writing paper is most often used) and fixed in a pair of fixer. The plate after cleaning from the powder is again suitable for consumption.

Fluoroscopy (X-ray transillumination)

Fluoroscopy is a method of X-ray examination in which an image of an object is obtained on a luminous (fluorescent) screen. The screen is cardboard coated with a special chemical composition. This composition under the influence of x-rays begins to glow. The intensity of the glow at each point of the screen is proportional to the number of X-ray quanta that fell on it. On the side facing the doctor, the screen is covered with lead glass, which protects the doctor from direct exposure to x-rays.

Benefits of Fluoroscopy The main advantage over radiography is the fact of the study in real time. This allows you to evaluate not only the structure of the organ, but also its displacement, contractility or extensibility, the passage of a contrast agent, and fullness. The method also allows you to quickly assess the localization of some changes, due to the rotation of the object of study during transillumination (multiprojection study). With radiography, this requires taking several pictures, which is not always possible (the patient left after the first picture without waiting for the results; a large flow of patients, in which pictures are taken in only one projection). Fluoroscopy allows you to control the implementation of some instrumental procedures - catheter placement, angioplasty (see angiography), fistulography.

X-ray methods research is based on the ability of X-rays to penetrate the organs and tissues of the human body.

Fluoroscopy- the method of transillumination, examination of the organ under study behind a special x-ray screen.

Radiography- a method of obtaining images, it is necessary to document the diagnosis of the disease, to monitor the observation of the functional state of the patient.

Dense fabrics delay the rays to varying degrees. Bone and parenchymal tissues are capable of retaining x-rays, and therefore do not require special patient preparation. To obtain more reliable data on the internal structure of the organ, the contrast method of research is used, which determines the "visibility" of these organs. The method is based on the introduction of special substances into the organs that delay x-rays.

As contrast agents in X-ray examination of the organs of the gastrointestinal tract (stomach and duodenum, intestines), a suspension of barium sulfate is used; in fluoroscopy of the kidneys and urinary tract, gallbladder and biliary tract, iodine contrast preparations are used.

Iodine-containing contrast agents are often administered intravenously. 1-2 days before the study, the nurse should test the patient's tolerance to the contrast agent. To do this, 1 ml of a contrast agent is injected very slowly intravenously and the patient's reaction is observed during the day. With the appearance of itching, runny nose, urticaria, tachycardia, weakness, lowering blood pressure, the use of radiopaque substances is contraindicated!

Fluorography- large-frame photography from the X-ray screen on a small film. The method is used for mass survey of the population.

Tomography- obtaining images of individual layers of the studied area: lungs, kidneys, brain, bones. Computed tomography is used to obtain layered images of the tissue under study.

Chest X-ray

Research objectives:

1. Diagnosis of diseases of the chest organs (inflammatory, neoplastic, and systemic diseases, heart defects and large vessels, lung, pleura.).

2. Control of the treatment of the disease.

Training objectives:

Training:

5. Find out if the patient can stand for the time necessary for the study and hold his breath.

6.Determine the method of transportation.

7. The patient must have a referral, outpatient card or medical history with him. If you have previously had lung studies, take the results (images).

8. The study is performed on a patient naked to the waist (a light T-shirt without radiopaque fasteners is possible).

Fluoroscopy and radiography of the esophagus, stomach and duodenum

Purpose of the study - assessment of radioanatomy and function of the esophagus, stomach and duodenum:

Identification of structural features, malformations, attitudes towards surrounding tissues;

Determination of violations of the motor function of these organs;

Identification of submucosal and infiltrating tumors.

Training objectives:

1. Ensure the possibility of conducting a study.

2. Get reliable results.

Training:

1. Explain to the patient the essence of the study and the rules for preparing for it.

2. Obtain the consent of the patient for the upcoming study.

3.Inform the patient about the exact time and place of the study.

4. Ask the patient to repeat the preparation for the study, especially on an outpatient basis.

5. For 2-3 days before the study, foods that cause flatulence (gas formation) are excluded from the patient's diet: rye bread, raw vegetables, fruits, milk, legumes, etc.

6. Dinner the night before must be no later than 19.00

7. On the evening before and in the morning no later than 2 hours before the examination, the patient is given a cleansing enema.

8. The study is carried out on an empty stomach, no need to drink, smoke, take medication.

9. When examining with a contrast agent (barium for X-ray studies), find out an allergic history; ability to absorb contrast.

10. Remove removable dentures.

11. The patient must have with him: a referral, an outpatient card / medical history, data from previous studies of these organs, if any.

12. Get rid of tight clothing and clothing that has radiopaque fasteners.

Note. Salt laxative instead of an enema should not be given, as it increases gas formation.

Breakfast is served to the patient in the ward.

The medical history after the study is returned to the department.

Possible Patient Problems

Real:

1. The appearance of discomfort, pain during examination and / or preparation for it.

2. Inability to swallow barium due to impaired swallowing reflex.

Potential:

1. The risk of developing pain due to spasms of the esophagus and stomach caused by the procedure itself (especially in the elderly) and when the stomach is distended.

2. Risk of vomiting.

3. The risk of developing an allergic reaction.

X-ray examination of the large intestine (irrigoscopy)

An x-ray examination of the large intestine is performed after the introduction of a barium suspension into the large intestine using an enema.

Research objectives:

1. determination of the shape, position, condition of the mucous membrane, tone and peristalsis of various sections of the colon.

2. Identification of malformations and pathological changes (polyps, tumors, diverticula, intestinal obstruction).

Training objectives:

1. Ensure the possibility of conducting a study.

2. Get reliable results.

Training:

1. Explain to the patient the essence of the study and the rules for preparing for it.

2. Obtain the consent of the patient for the upcoming study.

3.Inform the patient about the exact time and place of the study.

4. Ask the patient to repeat the preparation for the study, especially on an outpatient basis.

5.For three days before the study, a slag-free diet (see the composition of the diet in the appendix).

6 As prescribed by the doctor - taking enzymes and activated charcoal for three days before the study, chamomile infusion 1/3 cup three times a day.

7.the day before studies the last meal at 14 - 15 hours.

At the same time, fluid intake is not limited (you can drink broth, jelly, compote, and so on). Avoid dairy products!

8. On the day before the study, taking laxatives - orally or rectally.

9. At 22:00 you need to make two cleansing enemas of 1.5 - 2 liters. If, after the second enema, the wash water is colored, then make another enema. The water temperature should not be higher than 20 - 22 0 C (room temperature, when pouring, the water should feel cool).

10. In the morning on the day of the study you need to do two more enemas 3 hours before irrigoscopy (in the presence of dirty washings, repeat the enemas, achieving clean washings).

11. The patient must have with him: a referral, an outpatient card / medical history, data from a previous colonoscopy, barium enema, if performed.

12. Patients over 30 years of age should carry an ECG no more than a week old.

13. If the patient cannot go without food for so long (diabetics and so on), then in the morning, on the day of the study, you can eat a piece of meat or another high-protein breakfast.

Possible Patient Problems

Real:

1. Inability to diet.

2. Inability to take a certain position.

3. Insufficient preparation due to constipation for many days, non-compliance with the temperature regime of the water in the enema, the volume of water and the number of enemas.

Potential:

1. The risk of pain due to intestinal spasm caused by the procedure itself and / or preparation for it.

2.Risk violation of cardiac activity and respiration.

3. The risk of obtaining unreliable results with insufficient preparation, the impossibility of introducing a contrast enema.

Preparation option without enemas

The method is based on the effect of an osmotically active substance on the motility of the colon and the excretion of feces along with the drunk solution.

Procedure sequence:

1. Dissolve one packet of Fortrans in one liter of boiled water.

2. During this examination, for complete cleansing of the intestines, it is necessary to take 3 liters of an aqueous solution of the Fortrans preparation.

3. If the examination is carried out in the morning, then the prepared Fortrans solution is taken on the eve of the examination, 1 glass every 15 minutes (1 liter per hour) from 16:00 to 19:00. The effect of the drug on the intestines lasts up to 21 hours.

4. On the eve of the evening until 18:00, you can take a light dinner. Liquid is not limited.

Oral cholecystography

The study of the gallbladder and biliary tract is based on the ability of the liver to capture and accumulate iodine-containing contrast agents, and then excrete them with bile through the gallbladder and biliary tract. This allows you to get an image of the biliary tract. On the day of the examination in the X-ray room, the patient is given a choleretic breakfast, after 30-45 minutes a series of images are taken

Research objectives:

1. Assessment of the location and functions of the gallbladder and extrahepatic bile ducts.

2. Identification of malformations and pathological changes (presence of gallstones, tumors)

Training objectives:

1. Ensure the possibility of conducting a study.

2. Get reliable results.

Training:

1. Explain to the patient the essence of the study and the rules for preparing for it.

2. Obtain the consent of the patient for the upcoming study.

3.Inform the patient about the exact time and place of the study.

4. Ask the patient to repeat the preparation for the study, especially on an outpatient basis.

5. Find out if you are allergic to the contrast agent.

The day before:

6. When examining, pay attention to the skin and mucous membranes, in case of jaundice - tell the doctor.

7. Compliance with a slag-free diet for three days before the study

8. As prescribed by the doctor - taking enzymes and activated charcoal for three days before the study.

9. The night before - a light dinner no later than 19:00.

10. 12 hours before the study - taking a contrast agent orally for 1 hour at regular intervals, drinking sweet tea. (contrast agent is calculated on the patient's body weight). The maximum concentration of the drug in the gallbladder is 15-17 hours after its administration.

11. The night before and 2 hours before the study, the patient is given a cleansing enema

On the day of the study:

12. In the morning, come to the X-ray room on an empty stomach; You can not take medicine, smoke.

13. Bring with you 2 raw eggs or 200 g of sour cream and breakfast (tea, sandwich).

14. The patient must have with him: a referral, an outpatient card / medical history, data from previous studies of these organs, if any.

Possible Patient Problems

Real:

1. The impossibility of the procedure due to the appearance of jaundice (direct bilirubin absorbs the contrast agent).

Potential:

risk of an allergic reaction.

2. The risk of developing biliary colic when taking choleretic drugs (sour cream, egg yolks).

Perelman M. I., Koryakin V. A.

Fluorography. This method is widely used in mass surveys of the population. Another name for this X-ray method is photoradiography, since its essence is to photograph the image from the X-ray screen of an electron-optical amplifier onto film. Depending on the apparatus and the size of the film, frames of 70 x 70 or 100 x 100 mm are obtained.

Compared with conventional radiography, fluorography has certain advantages. It allows you to significantly increase the throughput of the X-ray machine, reduce the cost of film and its processing, and facilitate the storage of the X-ray archive.

The resolution of a high-quality lung fluorogram in frontal and lateral projections with a frame size of 100 x 100 mm is almost the same as that of an x-ray, although its information content is somewhat lower. Until recently, fluorography of the lungs with a frame size of 70 x 70 mm was used mainly for mass examinations of the population, and X-rays were performed when pathology was detected.

At present, a fluorogram with a frame size of 100 x 100 mm is successfully replacing the plain radiograph of the lungs, and fluorography is becoming increasingly common as a diagnostic method.

Radiography. An X-ray examination of the lungs begins with an overview image in the anterior direct projection (a film cassette at the anterior chest wall). In case of pathological changes in the posterior parts of the lungs, it is advisable to perform an overview image in the posterior direct projection (a film cassette at the posterior chest wall).

Next, a panoramic picture is taken in a lateral projection - right and left. When performing the right side image, the right side surface of the chest is adjacent to the film cassette, when performing the left one, the left one.

Radiographs in lateral projections are necessary to determine the localization of the pathological process in the lobes and segments of the lungs, to detect changes in the interlobar fissures and in the lungs behind the shadows of the heart and diaphragm.

With bilateral pulmonary pathology, it is better to take pictures not in lateral, but in oblique projections, on which separate images of the right and left lungs are obtained.

X-rays are usually taken at the height of inspiration. Under conditions of exhalation, pictures are taken to better identify the edge of the collapsed lung and pleural adhesions in the presence of pneumothorax, as well as to determine the displacement of the mediastinal organs in the pathology of the lungs and pleura.

To increase the information content of radiographs, you can increase the exposure time or the hardness of the x-rays. Such images are called overexposed and hard. They are performed in patients with exudative pleurisy and massive pleural overlays, seals of the lung tissue, after surgical operations on the lungs, to obtain a better image of the walls of the trachea and bronchi.

On hard and overexposed images, various structures can be detected in areas of intense darkening that are not visible in a normal image, but shadows of low intensity are not detected.

Plain radiographs in direct and lateral projections provide not only a general idea of the state of the organs of the chest cavity, but also important diagnostic information. They are supplemented with targeted images produced under the control of X-ray television with a narrow beam of rays.

In this case, the patient is given a position that allows you to free the image of the investigated lung field from the imposition of interfering bone and other formations.

To combine the information of images taken using soft, medium or hard beams, with a picture of superexposed images, to a large extent, electroradiography or xerography allows. The image is obtained on a selenium plate, and then transferred to plain white paper using graphite powder.

Compared with conventional radiographs, electroroentgenograms due to the “edge effect” better identify the contours of the trachea and bronchi, the edge of the collapsed lung in pneumothorax, cavities in the lungs, foci, residual pleural cavities, the level of a small amount of fluid, intermuscular and subcutaneous accumulations of air. An important advantage of electroroentgenography is its cost-effectiveness, since it is possible to do without x-ray film.

Tomography. Layer-by-layer x-ray examination is one of the main methods for diagnosing lung diseases, especially tuberculosis. High-quality tomograms provide additional information about the presence and localization of foci, areas of lung tissue decay, caverns, the condition of the bronchi and large pulmonary vessels.

In pulmonary tuberculosis, tomography is important for monitoring the process and for monitoring the effectiveness of treatment (resorption of foci and infiltration, closure of cavities).

A tomographic study plan is drawn up after radiography: the feasibility of survey or targeted tomography, projection, smearing direction (longitudinal or transverse), image mode, depth and number of layers are determined.

During panoramic tomography, images of several layers are taken: the first layer is 3–4 cm from the skin of the back, further layers are 1–2 cm later, the last, anterior, layer is 2–3 cm from the skin of the anterior chest wall.

A type of tomography is sonography: a thicker layer of lung tissue is examined. Sonography does not require high precision in choosing a layer, and a slightly worse image quality pays off with a wider amount of information contained in one image and a lower radiation exposure to the patient.

Features of pulmonary pathology are more clearly defined with electroroentgenotomography: the nature of the walls of the intrapulmonary cavities, changes in the lymph nodes, blood vessels are better visualized.

CT scan. This method of X-ray examination has received universal recognition and is used in all areas of clinical medicine. Computed tomography provides an image of the transverse layers of the human body (axial projection).

The X-ray tube, located in a circular frame, rotates around the longitudinal axis of the patient's body. A thin beam of rays passes through the layer under study at different angles and is captured by numerous scintillation detectors moving along with the tube.

The different density of the tissues through which the X-rays pass causes an unequal change in the intensity of their beam, which is recorded with high accuracy by detectors, processed by a computer and transformed into an image of the transverse layer under study on a television screen.

Thus, a computed tomogram is not a snapshot in the usual sense of the word, but a drawing made by a computer based on a mathematical analysis of the degree of absorption of x-rays by tissues of various densities (computational tomography).

Modern computed tomograms make it possible to examine transverse layers with a thickness of 2 to 10 mm. Scanning of one layer lasts several seconds. The brightness and contrast of the image can be changed within wide limits.

A significant increase in the contrast of the vessels can be obtained with intravenous administration of a small amount of radiopaque solution to the patient.

Axial (transverse) images can be reconstructed using a computer into straight, lateral and oblique tomograms of the examined area. All results of computed tomography are stored in the computer memory in parallel with the image on the television screen and can be reproduced on polaroid photographic paper or x-ray film.

The great advantage of computed tomography is the quantitative assessment of the density of the studied tissues and media, which is expressed in conventional units on the Hounsfield scale.

When examining the organs of the chest cavity, computed tomography makes it possible to clarify the localization and distribution of all pathological formations, to assess their size and to monitor changes in their size and density in dynamics.

The method is valuable in establishing the nature of pathological processes in the mediastinum, which cannot be determined with standard tomography. Computed tomography provides valuable information about the state of the pleural cavity, the part of the lung left after surgery, and allows for high accuracy of transthoracic biopsy and complex pleural punctures. When computed tomography of the respiratory organs, 6-12 standard tomographic sections are performed.

Fluoroscopy. For fluoroscopy, as a rule, electron-optical amplification of the x-ray image and x-ray television are used.

This method is used after radiography for certain indications: it is used to monitor the production of sighting images, X-ray bronchological, angiographic, bronchographic studies and fistulography: it is used to detect freely moving fluid in the pleural cavity, to establish the mobility of pathological formations and their connection with the chest wall and mediastinal organs, to determine the mobility of the diaphragm and the condition of the pleural sinuses.

Fluoroscopy is necessary for conducting tests with an increase and decrease in intrathoracic pressure (Valsalva and Muller tests, Goltzknecht-Jacobson symptom). Documentation of the results of these tests can be done using video recording and X-ray filming.

Angiopulmonography. This term is understood as an x-ray examination of the pulmonary artery and its branches with the introduction of a contrast agent. There are two main methods of angiopulmonography - general and selective.

When conducting a general angiopulmonography, a contrast solution is injected through a catheter into a vein of the arm, into the superior vena cava, or into the right cavities of the heart. X-rays are produced serially on a special ethnographic apparatus.

General angiopulmonography requires a significant amount of contrast agent (50-60 ml) and usually does not provide a clear image of the pulmonary vessels, especially with pathological changes in the lungs. Amputation of blood vessels does not always reflect their true state.

Selective angiopulmonography, although technically more difficult than general, is used more often. It is carried out after catheterization of the right atrium and ventricle of the heart and the corresponding branch of the pulmonary artery. Serial pictures are taken after the introduction of 10-12 ml of a contrast agent solution. The image of the vessels is clear.

Usually, selective angiopulmonography is combined with the registration of pressure in the pulmonary circulation and the study of blood gases.

Indications for angiopulmonography are limited. It is used to diagnose thrombosis and pulmonary embolism, as well as to determine the ability to straighten a long-term collapsed lung: the state of the vessels is used to judge the degree of pneumofibrosis.

Modern technical capabilities make it possible to perform general angiopulmonography in the form of numerical or digital angiopulmonography. It is carried out by injecting a small amount of a contrast agent into a vein. At the same time, computer processing of video signals allows you to get high-quality images.

Bronchial arteriography. The method consists in catheterization, contrasting and radiography of the bronchial arteries and their branches. The study is carried out under local anesthesia and X-ray television control.

A special needle with a mandrel is used to puncture the femoral artery below the inguinal fold. The mandrin is replaced with a metal conductor, through which a radiopaque catheter with a curved end is inserted into the lumen of the artery. Then the conductor is removed, and the catheter is advanced into the aorta.

With the tip of the catheter, the orifices of the bronchial arteries are sequentially searched and the catheter is inserted into them, and then a contrast agent (urografin, urotrast or their analogues) is injected at a rate of 35 ml, s in an amount of 5-12 ml. Produce serial x-rays.

The main indication for bronchial arteriography is pulmonary bleeding of unclear etiology and localization. In such cases, arteriograms can reveal expansion and pathological tortuosity of the bronchial arteries, the release of a contrast agent beyond their limits (extravasation), focal or diffuse hypervascularization, aneurysms of the bronchial arteries, their thrombosis, retrograde filling of the peripheral branches of the pulmonary artery through arterio-arterial anastomoses.

Contraindications to the study are severe atherosclerosis, obesity, severe pulmonary heart failure.

A complication of bronchial arteriography may be the occurrence of a hematoma in the area of the puncture of the femoral artery. A rare but serious complication is vascular lesions of the spinal cord with impaired function of the lower extremities and pelvic organs. Prevention of complications is ensured by strict adherence to the methodological and technical principles of the study.

Bronchography. Contrast X-ray examination of the bronchi is performed under local anesthesia in the form of positional (non-directional) or selective (directional) bronchography. With positional bronchography, the catheter is passed into the trachea through the nose. During the introduction of a contrast agent, the optimal position of the patient's body is given.

Selective bronchography is based on catheterization of the investigated bronchus. For its implementation, catheters of various designs are used and different techniques are used.

Bronchography is performed on an empty stomach. With a significant amount of sputum, bronchoscopy is preliminarily performed to sanitize the bronchial tree.

For local anesthesia, 10-15 ml of a 2% lidocaine solution is used. A soft catheter is passed through the nose and, under the control of X-ray television, is installed in the bronchus under study.

The control is carried out by spraying tantalum powder or, more often, water-soluble preparations, for example 5-10 ml of propyliodone. After the administration of the drug, the patient is offered to exhale sharply and cough slightly. In this case, the contrast agent is relatively evenly distributed over the mucous membrane and provides a contour image of the walls of the bronchi. After 2-3 days, propyliodone is hydrolyzed and excreted from the body by the kidneys without separation of free iodine.

Conducting a study under the control of X-ray television and with video recording makes it possible to judge the elasticity and mobility of the bronchial walls.

Previously, bronchography was widely used. Currently, it is used to determine the presence of bronchiectasis and determine their localization and form. Sometimes it is used for better orientation with transbronchial biopsy, as well as with large fibrous changes, if other methods do not allow us to determine the features of the pathology.

The main contraindications are acute inflammatory processes in the respiratory organs, pulmonary bleeding.

Pleurography. X-ray examination of the contrasted pleural cavity is used mainly in patients with pleural empyema to clarify the boundaries of the purulent cavity.

First, a pleural puncture is performed and the pleural contents are aspirated. Then, under the control of X-ray television, 30-40 ml of a warm radiopaque substance (propyliodone, urographin, verografin) is injected into the pleural cavity. Pictures are taken in different projections, changing the position of the patient. After the end of the study, the contrast agent with the remnants of the pleural contents is sucked off.

Fistulography. The method is used to examine patients with various types of thoracic fistulas, including thoracic and thoracobronchial fistulas.

The fistulous passage is filled with a radiopaque substance and then radiography is performed. During the study and after analyzing the images, the anatomical features of the fistula are revealed, its communication with the pleural cavity and the bronchial tree is established.

Before fistulography, it is advisable to establish the direction of the fistulous passage with the help of probing. A contrast agent is injected into the fistula with a syringe under the control of X-ray television. Apply yodolipol, oily and aqueous solutions of propioliodon. Radiographs are produced in several projections.

In the case of penetration of the contrast agent into the bronchial tree, a retrograde fistulobronchography is obtained. After the end of the study, the drug is sucked off through the fistula, if possible, and the patient should cough well.