Radiation diagnostic methods and their characteristics. Radiation diagnostics. Radiation diagnostic methods

Radiation diagnostics is widely used both in somatic diseases and in dentistry. In the Russian Federation, more than 115 million x-ray examinations, more than 70 million ultrasound examinations and more than 3 million radionuclide examinations are performed annually.

Radiation diagnostic technology is a practical discipline that studies the effects of different types of radiation on the human body. Its goal is to identify hidden diseases, by studying the morphology and functions of healthy organs, as well as those with pathologies, including all systems of human life.

Advantages and disadvantages

Advantages:

ability to observe work internal organs and human life systems;
analyze, draw conclusions and select required method diagnostic-based therapy.

Disadvantage: threat of unwanted radiation exposure to the patient and medical personnel.

Methods and techniques

Radiation diagnostics is divided into the following branches:

radiology (this also includes computed tomography);
radionuclide diagnostics;
magnetic resonance imaging;
medical thermography;
interventional radiology.

X-ray examination, which is based on the method of creating an x-ray image of the internal organs of a person, is divided into:

radiography;
teleradiography;
electroradiography;
fluoroscopy;
fluorography;
digital radiography;
linear tomography.

In this study, it is important to conduct a qualitative assessment of the patient’s radiograph and correctly calculate the radiation dose load on the patient.

Ultrasound examination, during which an ultrasound image is formed, includes an analysis of the morphology and vital systems of a person. Helps identify inflammation, pathologies and other abnormalities in the body of the subject.

Divided into:

one-dimensional echography;
two-dimensional echography;
Dopplerography;
duplex sonography.

A study based on computed tomography, during which a CT image is generated using a scanner, includes the following scanning principles:

consistent;
spiral;
dynamic.

Magnetic resonance imaging (MRI) includes the following techniques:

MR angiography;
MR urography;
MR cholangiography.

Radionuclide research involves the use of radioactive isotopes, radionuclides and is divided into:

radiography;
radiometry;
radionuclide imaging.

Photo gallery

Interventional radiology Medical thermography Radionuclide diagnostics

X-ray diagnostics

X-ray diagnostics recognizes diseases and damage in human organs and vital systems based on the study x-rays. The method allows you to detect the development of diseases, determining the degree of organ damage. Provides information about general condition patients.

In medicine, fluoroscopy is used to study the condition of organs and work processes. Provides information about the location of internal organs and helps to identify pathological processes occurring in them.

The following radiation diagnostic methods should also be noted:

Radiography helps to obtain a fixed image of any part of the body using x-ray radiation. It examines the functioning of the lungs, heart, diaphragm and musculoskeletal system.
Fluorography is done on the basis of photographing X-ray images (smaller photographic film is used). In this way, the lungs, bronchi, mammary glands and paranasal sinuses are examined.
Tomography is an x-ray film taken layer by layer. Used to examine the lungs, liver, kidneys, bones and joints.
Rheography examines blood circulation by measuring pulse waves caused by the resistance of vessel walls under the influence of electrical currents. It is used to diagnose vascular disorders in the brain, and also check the lungs, heart, liver, limbs.

Radionuclide diagnostics

It involves recording the radiation of a radioactive substance artificially introduced into the body (radiopharmaceuticals). Contributes to the study of the human body as a whole, as well as its cellular metabolism. Is an important step in identifying oncological diseases. Determines the activity of cells affected by cancer, disease processes, helping to evaluate cancer treatment methods, preventing relapses of the disease.

The technique allows timely detection of the formation of malignant neoplasms in the early stages. Helps reduce the mortality rate from cancer, reducing the number of relapses in cancer patients.

Ultrasound diagnostics

Ultrasound diagnostics (ultrasound) is a process based on a minimally invasive method of studying the human body. Its essence lies in the features sound wave, its ability to be reflected from the surfaces of internal organs. Refers to the modern and most advanced research methods.

Features of ultrasound examination:

high degree of security;
high degree of information content;
high percentage of detection of pathological abnormalities at an early stage of development;
no radiation exposure;
diagnostics of children from a very early age;
ability to conduct research an unlimited number of times.

Magnetic resonance imaging

The method is based on the properties of the atomic nucleus. Once inside a magnetic field, atoms emit energy of a certain frequency. IN medical research The resonance of radiation from the nucleus of a hydrogen atom is often used. The degree of signal intensity is directly related to the percentage of water in the tissues of the organ under study. The computer transforms the resonant radiation into a high-contrast tomographic image.

MRI stands out from other techniques in its ability to provide information not only on structural changes, but also on the local chemical state of the body. This type of test is non-invasive and does not involve the use of ionizing radiation.

MRI capabilities:

allows you to study the anatomical, physiological and biochemical features of the heart;
helps to recognize vascular aneurysms in time;
provides information about blood flow processes and the condition of large vessels.

Disadvantages of MRI:

high cost of equipment;
inability to examine patients with implants that disrupt the magnetic field.

Thermography

The method involves recording visible images of a thermal field in the human body that emits an infrared pulse that can be read directly. Or shown on a computer screen as a thermal image. The image obtained in this way is called a thermogram.

Thermography is characterized by high measurement accuracy. It makes it possible to determine the temperature difference in the human body up to 0.09%. This difference occurs as a result of changes in blood circulation within the tissues of the body. At low temperatures, we can talk about impaired blood flow. High fever is a symptom inflammatory process in organism.

Microwave thermometry

Radiothermometry (microwave thermometry) is the process of measuring temperatures in tissues and inside organs of the body based on their own radiation. Doctors measure the temperature inside the tissue column at a certain depth using microwave radiometers. When the temperature of the skin in a specific section is established, the temperature of the depth of the column is then calculated. The same thing happens when recording the temperature of waves of different lengths.

The effectiveness of the method lies in the fact that the temperature of the deep tissue is basically stable, but quickly changes when exposed to medications. For example, if you use vasodilators. Based on the data obtained, it is possible to carry out basic research diseases of blood vessels and tissues. And achieve a reduction in disease levels.

Magnetic resonance spectrometry

Magnetic resonance spectroscopy (MR spectrometry) is a non-invasive method for studying brain metabolism. Proton spectrometry is based on changes in the resonance frequencies of proton bonds that are found in different chemical compounds. connections.

MR spectroscopy is used in oncology research. Based on the data obtained, it is possible to trace the growth of tumors, with a further search for solutions to eliminate them.

Clinical practice uses MR spectrometry:

during the postoperative period;
in the diagnosis of tumor growth;
tumor recurrences;
with radiation necrosis.

For complex cases, spectrometry is an additional option in differential diagnoses along with perfusion-weighted imaging.

Another nuance when using MR spectrometry is to distinguish between identified primary and secondary tissue damage. Differentiation of the latter with infectious processes. Diagnosis of abscesses in the brain based on diffusion-weighted analysis is especially important.

Interventional radiology

Treatment with interventional radiology is based on the use of a catheter and other low-impact instruments together with the use of local anesthesia.

According to the methods of influencing percutaneous accesses, interventional radiology is divided into:

vascular intervention;
not vascular intervention.

IN radiology reveals the extent of the disease and performs puncture biopsies based on histological studies. Directly related to percutaneous non-surgical treatment methods.

For the treatment of oncology using interventional radiology, local anesthesia is used. Next, injection penetration occurs into groin area through the arteries. Medicine or insulating particles are then injected into the tumor.

Elimination of blockage of blood vessels, all except the heart vessels, is carried out using balloon angioplasty. The same applies to the treatment of aneurysms, by freeing the veins by administering medication through the affected area. Which subsequently leads to the disappearance of varicose veins and other neoplasms.

This video will tell you more about the mediastinum in x-ray imaging. The video was filmed by the channel: Secrets of CT and MRI.

Types and use of radiocontrast agents in radiology diagnostics

In some cases, it is necessary to visualize anatomical structures and organs that are indistinguishable on plain radiographs. To study in such a situation, the method of creating artificial contrast is used. To do this, a special substance is injected into the area that needs to be examined, increasing the contrast of the area in the image. Substances of this kind have the ability to enhance or, conversely, reduce the absorption of X-ray radiation.

Contrast agents are divided into drugs:

alcohol-soluble;
fat soluble;
insoluble;
water-soluble nonionic and ionic;
with high atomic weight;
with low atomic weight.

Fat-soluble X-ray contrast agents are created on the basis of vegetable oils and are used in diagnosing the structure of hollow organs:

bronchi;
spinal column;
spinal cord.

Alcohol-soluble substances are used for research:

biliary tract;
gallbladder;
intracranial canals;
spinal canals;
lymphatic vessels (lymphography).

Insoluble drugs are created based on barium. They are used for oral administration. Typically, such drugs are used to examine the components of the digestive system. Barium sulfate is taken in the form of a powder, watery suspension or paste.

Substances with low atomic weight include gaseous preparations that reduce the absorption of X-rays. Typically, gases are injected to compete with X-rays into body cavities or hollow organs.

Substances with high atomic weight absorb x-rays and are divided into:

containing iodine;
not containing iodine.

Water-soluble substances are administered intravenously for radiology studies:

lymphatic vessels;
urinary system;
blood vessels, etc.

In what cases is radiodiagnosis indicated?

Ionizing radiation is used daily in hospitals and clinics to perform diagnostic imaging procedures. Typically, radiation diagnostics is used to make an accurate diagnosis, identify a disease or injury.

Only a qualified doctor can prescribe a test. However, there are not only diagnostic, but also preventive research recommendations. For example, women over forty years of age are recommended to undergo preventive mammography at least once every two years. Educational institutions often require annual fluorography.

Contraindications

Radiation diagnostics has virtually no absolute contraindications. A complete ban on diagnostics is possible in some cases if there are metal objects in the patient’s body (such as an implant, clips, etc.). The second factor in which the procedure is unacceptable is the presence of pacemakers.

Relative prohibitions on radiation diagnostics include:

the patient's pregnancy;
if the patient is under 14 years of age;
the patient’s body contains prosthetic heart valves;
the patient has mental disorders;
insulin pumps are implanted in the patient’s body;
the patient experiences claustrophobia;
it is necessary to artificially maintain the basic functions of the body.

Where is radiation diagnostics used?

Radiation diagnostics is widely used to detect diseases in the following branches of medicine:

pediatrics;
dentistry;
cardiology;
neurology;
traumatology;
orthopedics;
urology;
gastroenterology.

Radiation diagnostics is also carried out for:

emergency conditions;
respiratory diseases;
pregnancy.

In pediatrics

A significant factor that can affect the results of a medical examination is the implementation timely diagnosis childhood diseases.

Some of the important factors limiting radiographic studies in pediatrics include:

radiation exposure;
low specificity;
insufficient resolution.

If we talk about important methods of radiation research, the use of which greatly increases the information content of the procedure, it is worth highlighting computed tomography. It is best to use ultrasound and magnetic resonance imaging in pediatrics, as they completely eliminate the danger ionizing radiation.

A safe method for examining children is MRI, due to the good possibility of using tissue contrast, as well as multiplanar studies.

Radiation examinations for children can only be prescribed by an experienced pediatrician.

In dentistry

Radiation diagnostics are often used in dentistry to examine various abnormalities, for example:

periodontitis;
bone abnormalities;
tooth deformations.

Most often used in maxillofacial diagnostics:

extraoral radiography of jaws and teeth;
;
survey radiography.

In cardiology and neurology

MSCT or multislice computed tomography allows you to examine not only the heart itself, but also the coronary vessels.

This examination is the most comprehensive and allows you to identify and timely diagnose a wide range of diseases, for example:

various heart defects;
aortic stenosis;
hypertrophic cardiopathy;
heart tumor.

Radiation diagnostics of the cardiovascular system (cardiovascular system) allows you to assess the area of closure of the lumen of blood vessels and identify plaques.

Radiological diagnostics have also been used in neurology. Patients with intervertebral disc diseases (herniation and protrusion) receive more accurate diagnoses thanks to radiation diagnostics.

In traumatology and orthopedics

The most common method of radiation examination in traumatology and orthopedics is x-ray.

The examination reveals:

musculoskeletal injuries;
pathologies and changes in the musculoskeletal system and osteoarticular tissue;
rheumatic processes.

Most effective methods radiology diagnostics in traumatology and orthopedics:

traditional radiography;
radiography in two mutually perpendicular projections;

Respiratory diseases

The most commonly used methods for examining the respiratory system are:

fluorography of the chest organs;

Fluoroscopy and linear tomography are used less frequently.

Today, it is acceptable to replace fluorography with low-dose CT of the chest organs.

Fluoroscopy in diagnosing the respiratory system is significantly limited by the serious radiation exposure to the patient and lower resolution. It is carried out exclusively in accordance with strict indications, after fluorography and radiography. Linear tomography is prescribed only if it is impossible to perform a CT scan.

The examination allows you to exclude or confirm diseases such as:

chronic obstructive pulmonary disease (COPD);
pneumonia;
tuberculosis.

In gastroenterology

Radiation diagnostics of the gastrointestinal tract (GIT) is usually carried out using X-ray contrast agents.

Thus they can:

diagnose a number of abnormalities (for example, tracheoesophageal fistula);
examine the esophagus;
examine the duodenum.

Sometimes specialists use radiation diagnostics to monitor and film the process of swallowing liquid and solid food in order to analyze and identify pathologies.

In urology and neurology

Sonography and ultrasound are among the most common methods for examining the urinary system. Typically, such studies can exclude or diagnose cancer or a cyst. Radiation diagnostics helps to visualize the study and provides more information than just communication with the patient and palpation. The procedure takes little time and is painless for the patient, while increasing the accuracy of the diagnosis.

For emergencies

By X-ray examination it is possible to identify:

traumatic liver injury;
hydrothorax;
intracerebral hematomas;
effusion into the abdominal cavity;
head injuries;
fractures;
hemorrhages and cerebral ischemia.

Radiation diagnostics in emergency conditions allows you to correctly assess the patient’s condition and promptly carry out rheumatological procedures.

During pregnancy

Using various procedures, diagnosis is possible already in the fetus.

Thanks to ultrasound and colorectal dosage it is possible to:

identify various vascular pathologies;
kidney and genitourinary tract diseases;
disruption of fetal development.

At the moment, only ultrasound, of all the methods of radiation diagnostics, is considered a completely safe procedure when examining women during pregnancy. To conduct any other diagnostic tests on pregnant women, they must have appropriate medical indications. And in this case, the fact of pregnancy itself is not enough. If an X-ray or MRI is not one hundred percent confirmed by medical indications, the doctor will be forced to look for an opportunity to reschedule the examination for the period after childbirth.

The opinion of experts on this matter is that CT, MRI or X-ray studies should not be carried out in the first trimester of pregnancy. Because at this time the process of fetal formation occurs and the impact of any radiation diagnostic methods on the condition of the embryo is not completely known.

Send your good work in the knowledge base is simple. Use the form below

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

Posted on http://allbest.ru

Introduction

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

All treatments used in radiation diagnostics are divided into non-ionizing and ionizing.

Non-ionizing radiation is electromagnetic radiation of various frequencies that does not cause ionization of atoms and molecules, i.e. their disintegration into oppositely charged particles - ions. These include thermal (infrared - IR) radiation and resonant radiation, which occurs in an object (the human body) placed in a stable magnetic field under the influence of high-frequency electromagnetic pulses. Also include ultrasonic waves, which are elastic vibrations of the medium.

Ionizing radiation can ionize atoms environment, including the atoms that make up human tissue. All these radiations are divided into two groups: quantum (i.e., consisting of photons) and corpuscular (consisting of particles). This division is largely arbitrary, since any radiation has a dual nature and, under certain conditions, exhibits either the properties of a wave or the properties of a particle. Quantum ionizing radiation includes bremsstrahlung (X-ray) radiation and gamma radiation. Corpuscular radiation includes beams of electrons, protons, neutrons, mesons and other particles.

To obtain a differentiated image of tissues that absorb radiation approximately equally, artificial contrast is used.

There are two ways to contrast organs. One of them is the direct (mechanical) introduction of a contrast agent into the organ cavity - into the esophagus, stomach, intestines, into the lacrimal or salivary ducts, bile ducts, urinary tracts, into the uterine cavity, bronchi, blood and lymphatic vessels or into the 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 contrast method is based on the ability of some organs to absorb a substance introduced into the body from the blood, concentrate and secrete it. This principle - concentration and elimination - is used in X-ray contrasting of the excretory system and biliary tract.

The basic requirements for radiocontrast substances are obvious: creation of high image contrast, harmlessness when introduced into the patient’s body, and rapid removal from the body.

The following contrast agents are currently used in radiology practice.

1. Preparations of barium sulfate (BaSO4). An aqueous suspension of barium sulfate is the main preparation for studying the digestive canal. It is insoluble in water and digestive juices and is harmless. Used as a suspension in a concentration of 1:1 or higher - up to 5:1. To give the drug additional properties (slowing down the sedimentation of solid barium particles, increasing adhesion to the mucous membrane), chemically active substances (tannin, sodium citrate, sorbitol, etc.) are added to the aqueous suspension; gelatin and food cellulose are added to increase viscosity. There are ready-made official preparations of barium sulfate that meet all of the above requirements.

2. Iodine-containing solutions organic compounds. This is a large group of drugs, which are mainly derivatives of certain aromatic acids - benzoic, adipic, phenylpropionic, etc. The drugs are used for contrasting blood vessels and heart cavities. These include, for example, urografin, trazograf, triombrast, etc. These drugs are secreted by the urinary system, so they can be used to study the pyelocaliceal complex of the kidneys, ureters, and bladder. IN Lately A new generation of iodine-containing organic compounds has appeared - nonionic (first monomers - Omnipaque, Ultravist, then dimers - iodixanol, iotrolan). Their osmolarity is significantly lower than ionic ones, and approaches the osmolarity of blood plasma (300 my). As a result, they are significantly less toxic than ionic monomers. A number of iodine-containing drugs are captured from the blood by the liver and excreted in the bile, so they are used for contrasting the biliary tract. To contrast the gallbladder, iodide preparations are used that are absorbed in the intestine (cholevid).

3. Iodized oils. These preparations are an emulsion of iodine compounds in vegetable oils (peach, poppy). They have gained popularity as tools used in the study of bronchi, lymphatic vessels, uterine cavity, and fistula tracts. Ultra-liquid iodized oils (lipoidol) are especially good, which are characterized by high contrast and have little irritation to tissues. Iodine-containing drugs, especially the ionic group, can cause allergic reactions and have a toxic effect on the body

General allergic manifestations are observed in the skin and mucous membranes (conjunctivitis, rhinitis, urticaria, swelling of the mucous membrane of the larynx, bronchi, trachea), cardiovascular system (low blood pressure, collapse), central nervous system (convulsions, sometimes paralysis), kidneys (violation of excretory function). These reactions are usually transient, but can reach high degree severity and even lead to death. In this regard, before introducing iodine-containing drugs into the blood, especially high-osmolar ones from the ionic group, it is necessary to conduct a biological test: carefully inject 1 ml of a radiocontrast drug intravenously and wait 2-3 minutes, carefully monitoring the patient’s condition. Only in the absence of an allergic reaction is the main dose administered, which varies from 20 to 100 ml in different studies.

4. Gases (nitrous oxide, carbon dioxide, ordinary air). Only carbon dioxide can be used for injection into the blood due to its high solubility. When administered into body cavities and cellular spaces, nitrous oxide is also used to avoid gas embolism. It is permissible to introduce ordinary air into the digestive canal.

1.X-ray methods

X-rays were discovered on November 8, 1895. Professor of physics at the University of Würzburg Wilhelm Conrad Roentgen (1845-1923).

The X-ray method is a method of studying the structure and function of various organs and systems, based on qualitative and/or quantitative analysis of a beam of X-ray radiation passed through the human body. X-ray radiation generated in the anode of the X-ray tube is directed at the patient, in whose body it is partially absorbed and scattered, and partially passes through

X-rays are one of the types of electromagnetic waves with a length of approximately 80 to 10~5 nm, which occupy a place in the general wave spectrum between ultraviolet rays and -rays. The speed of propagation of X-rays is equal to the speed of light 300,000 km/s.

X-rays are formed at the moment of collision of a stream of accelerated electrons with the anode substance. When electrons interact with a target, 99% of their kinetic energy is converted into thermal energy and only 1% into x-ray radiation. An X-ray tube consists of a glass cylinder into which 2 electrodes are soldered: a cathode and an anode. The air has been pumped out of the glass balloon: the movement of electrons from the cathode to the anode is possible only under conditions of relative vacuum. The cathode has a filament, which is a tightly twisted tungsten spiral. When submitting electric current Electron emission occurs on the filament, in which electrons are separated from the filament and form an electron cloud near the cathode. This cloud is concentrated at the focusing cup of the cathode, which sets the direction of electron motion. The cup is a small depression in the cathode. The anode, in turn, contains a tungsten metal plate onto which electrons are focused - this is where X-rays are produced. There are 2 transformers connected to the electronic tube: a step-down and a step-up. A step-down transformer heats the tungsten coil with low voltage (5-15 volts), resulting in electron emission. A step-up, or high-voltage, transformer fits directly to the cathode and anode, which are supplied with a voltage of 20-140 kilovolts. Both transformers are placed in the high-voltage block of the X-ray machine, which is filled with transformer oil, which ensures cooling of the transformers and their reliable insulation. After an electron cloud has been formed using a step-down transformer, the step-up transformer is turned on, and high-voltage voltage is applied to both poles of the electrical circuit: a positive pulse to the anode, and a negative pulse to the cathode. Negatively charged electrons are repelled from the negatively charged cathode and tend to the positively charged anode - due to this potential difference, a high speed of movement is achieved - 100 thousand km/s. At this speed, electrons bombard the tungsten plate of the anode, completing an electrical circuit, resulting in x-rays and thermal energy. X-ray radiation is divided into bremsstrahlung and characteristic. Bremsstrahlung occurs due to a sharp slowdown in the speed of electrons emitted by a tungsten helix. Characteristic radiation occurs at the moment of restructuring of the electronic shells of atoms. Both of these types are formed in the X-ray tube at the moment of collision of accelerated electrons with atoms of the anode substance. The emission spectrum of an X-ray tube is a superposition of bremsstrahlung and characteristic X-rays.

Properties of X-rays.

1. Penetrating ability; due to the short wavelength X-rays can penetrate objects and are impervious to visible light.

2. Ability to be absorbed and dispersed; When absorbed, part of the X-rays with the longest wavelength disappears, completely transferring their energy to the substance. When scattered, it deviates from the original direction and does not carry useful information. Some of the rays pass completely through the object with a change in their characteristics. Thus, an image is formed.

3. Cause fluorescence (glow). This phenomenon is used to create special luminous screens for the purpose of visual observation of X-ray radiation, sometimes to enhance the effect of X-rays on a photographic plate.

4. Have a photochemical effect; allows you to record images on photosensitive materials.

5. Cause ionization of the substance. This property is used in dosimetry to quantify the effect of this type of radiation.

6. They spread in a straight line, which makes it possible to obtain an X-ray image that follows the shape of the material being studied.

7. Capable of polarization.

8. X-rays are characterized by diffraction and interference.

9. They are invisible.

Kinds X-ray methods.

1.X-ray (X-ray).

Radiography is a method of x-ray examination in which a fixed x-ray image of an object is obtained on a solid medium. Such media can be X-ray film, photographic film, digital detector, etc.

Film radiography is performed either on a universal X-ray machine or on a special stand designed only for this type of research. The inner walls of the cassette are covered with intensifying screens, between which the X-ray film is placed.

Intensifying screens contain a phosphor, which glows under the influence of X-ray radiation and, thus acting on the film, enhances its photochemical effect. The main purpose of intensifying screens is to reduce exposure, and therefore radiation exposure, to the patient.

Depending on the purpose, intensifying screens are divided into standard, fine-grained (they have a fine phosphor grain, reduced light output, but very high spatial resolution), which are used in osteology, and high-speed (with large phosphor grains, high light output, but reduced resolution), which used when conducting research in children and fast-moving objects, such as the heart.

The body part being examined is placed as close to the cassette as possible to reduce projection distortion (basically magnification) that occurs due to the divergent nature of the X-ray beam. In addition, this arrangement provides the necessary image sharpness. The emitter is installed so that the central beam passes through the center of the body part being removed and is perpendicular to the film. In some cases, for example when researching temporal bone, apply an inclined position of the emitter.

Radiography can be performed in a vertical, horizontal and inclined position of the patient, as well as in a lateral position. Filming in different positions allows us to judge the displacement of organs and identify some important diagnostic signs, such as fluid spreading in the pleural cavity or fluid levels in bowel loops.

Technique for recording X-ray radiation.

Scheme 1. Conditions for conventional radiography (I) and teleradiography (II): 1 - X-ray tube; 2 - beam of X-rays; 3 - object of study; 4 - film cassette.

Obtaining an image is based on the attenuation of X-ray radiation as it passes through various tissues and its subsequent recording on X-ray sensitive film. As a result of passing through formations of different densities and compositions, the radiation beam is scattered and decelerated, and therefore an image is formed on the film varying degrees intensity. As a result, the film produces an averaged, summation image of all tissues (shadow). It follows from this that in order to obtain an adequate x-ray, it is necessary to study radiologically heterogeneous formations.

An image that shows a part of the body (head, pelvis, etc.) or an entire organ (lungs, stomach) is called a survey. Images in which an image of the part of the organ of interest to the doctor is obtained in the optimal projection, most advantageous for studying a particular detail, are called targeted. Pictures can be single or serial. The series may consist of 2-3 radiographs on which different states organ (for example, gastric peristalsis).

An X-ray photograph is a negative in relation to the image visible on a fluorescent screen when transilluminated. Therefore, transparent areas on an x-ray are called dark (“darkenings”), and dark ones are called light (“clearances”). The X-ray image is summative, planar. This circumstance leads to the loss of the image of many elements of the object, since the image of some parts is superimposed on the shadow of others. This leads to the basic rule of x-ray examination: examination of any part of the body (organ) must be carried out in at least two mutually perpendicular projections - frontal and lateral. In addition to them, images in oblique and axial (axial) projections may be needed.

For X-ray image analysis, an X-ray image is recorded on an illuminating device with a bright screen - a negatoscope.

Previously, selenium plates were used as X-ray image receivers, which were charged on special devices before exposure. The image was then transferred to writing paper. The method is called electroradiography.

In electron-optical digital radiography, the X-ray image obtained in a television camera, after amplification, is transferred to an analog-digital one. All electrical signals carrying information about the object under study are converted into a series of numbers. The digital information then enters the computer, where it is processed according to pre-compiled programs. Using a computer, you can improve the quality of the image, increase its contrast, clear it of noise, and highlight details or contours of interest to the doctor.

The advantages of digital radiography include: high image quality, reduced radiation exposure, the ability to save images on magnetic media with all the ensuing consequences: ease of storage, the ability to create organized archives with quick access to data and image transmission over distances - both inside and outside the hospital.

Disadvantages of radiography: the presence of ionizing radiation that can cause harmful effects per patient; The information content of classical radiography is significantly lower than such modern medical imaging methods 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 layer-by-layer series of images obtained by modern tomographic methods. Without the use of contrast agents, radiography is not informative enough to analyze changes in soft tissues that differ little in density (for example, when studying the abdominal organs).

2. Fluoroscopy (x-ray scanning)

Fluoroscopy is a method of x-ray examination in which an image of an object is obtained on a luminous (fluorescent) screen. The intensity of the glow at each point of the screen is proportional to the number of X-ray quanta that hit it. On the side facing the doctor, the screen is covered with lead glass, protecting the doctor from direct exposure to X-ray radiation.

X-ray television transmission is used as an improved method of fluoroscopy. It is performed using an X-ray image intensifier (XI), which includes an X-ray electron-optical converter (X-ray electron-optical converter) and a closed-circuit television system.

X-ray scope

The REOP is a vacuum flask, inside of which, on one side, 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 appears during transillumination on the fluorescent screen is transformed at the photocathode into a stream of electrons. Under the influence of the accelerating field and as a result of focusing (increasing the flux density), the energy of the electrons increases significantly - several thousand times. Getting on the cathodoluminescent screen, the electron flow creates a visible image on it, similar to the original one, but very bright.

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 sent for processing to the television channel unit, and then to the screen of a video control device or, more simply, to the TV screen. If necessary, the image can be recorded using a video recorder.

3. Fluorography

Fluorography is a method of x-ray examination that involves photographing an image from an x-ray fluorescent screen or an electron-optical converter screen onto small-format photographic film.

Fluorography provides a reduced image of an object. There are small-frame (for example, 24×24 mm or 35×35 mm) and large-frame (in particular, 70×70 mm or 100×100 mm) techniques. The latter approaches radiography in diagnostic capabilities. Fluorography is used mainly to study the chest organs, mammary glands, and skeletal system.

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

On fluorograms, image details are captured better than with fluoroscopy or X-ray television transmission, but slightly worse (4-5%) compared to conventional radiographs.

For verification studies, fluorographs of stationary and mobile types are used. The first are placed in clinics, medical units, dispensaries, and hospitals. Mobile fluorographs are mounted on automobile chassis or in railway cars. Shooting in both fluorographs is carried out on roll film, which is then developed in special tanks. Special gastrofluorographs have been created to examine the esophagus, stomach and duodenum.

Finished fluorograms are examined with a special flashlight - a fluoroscope, which magnifies the image. From the general population of those examined, individuals are selected whose fluorograms indicate pathological changes. They are sent for additional examination, which is carried out on x-ray diagnostic units using all the necessary x-ray research methods.

Important advantages of fluorography are the ability to examine a large number of people in a short time (high throughput), cost-effectiveness, ease of storing fluorograms, and allows early detection of minimal pathological changes in organs.

The use of fluorography turned out to be most effective for identifying hidden lung diseases, primarily tuberculosis and cancer. The frequency of verification surveys is determined taking into account the age of people, the nature of their labor activity, local epidemiological conditions

4. Tomography

Tomography (from the Greek tomos - layer) is a method of layer-by-layer x-ray examination.

In tomography, due to the movement of the X-ray tube at a certain speed during shooting, the film produces a sharp image of only those structures that are located at a certain, predetermined depth. Shadows of organs and formations located at a shallower or greater depth are “blurred” and do not overlap the main image. Tomography facilitates the identification of tumors, inflammatory infiltrates and other pathological formations.

The tomography effect is achieved through continuous movement during imaging of two of the three components of the X-ray emitter-patient-film system. Most often, the emitter and film move while the patient remains motionless. In this case, the emitter and the film move in an arc, a straight line or a more complex trajectory, but always in opposite directions. With such a movement, the image of most of the details on the x-ray image turns out to be unclear, smeared, and the image is sharp only of those formations that are located at the level of the center of rotation of the emitter-film system.

Structurally, tomographs are made in the form of additional stands or a special device for a universal rotating stand. If you change the level of the center of rotation of the emitter-film system on the tomograph, then the level of the selected layer will change. The thickness of the selected layer depends on the amplitude of movement of the above-mentioned system: the larger it is, the thinner the tomographic layer will be. The usual value of this angle is from 20 to 50°. If a very small displacement angle is chosen, on the order of 3-5°, then an image of a thick layer, essentially an entire zone, is obtained.

Types of tomography

Linear tomography (classical tomography) is a method of x-ray examination with which you can take a picture of a layer lying at a certain depth of the object under study. This type of research is based on the movement of two of three components (X-ray tube, X-ray film, object of study). The system closest to modern linear tomography was proposed by Maer; in 1914, he proposed moving the X-ray tube parallel to the patient’s body.

Panoramic tomography is a method of x-ray examination with which you can obtain an image of a curved layer lying at a certain depth of the object under study.

In medicine, panoramic tomography is used in research facial skull, primarily in the diagnosis of diseases of the dental system. Using the movement of the X-ray emitter and film cassette along special trajectories, an image in the form of a cylindrical surface is isolated. This allows you to obtain an image showing all the patient’s teeth, which is necessary for prosthetics and is useful for periodontal disease, in traumatology and a number of other cases. Diagnostic studies are performed using pantomographic dental devices.

Computed tomography is a layer-by-layer X-ray examination, based on a computer reconstruction of the image obtained by circular scanning of an object (Pє English scan - quickly view) with a narrow beam of X-ray radiation.

CT machine

Computed tomography (CT) images are produced using a narrow, rotating beam of X-rays and a system of sensors arranged in a circle called a gantry. Passing through tissue, radiation is attenuated according to the density and atomic composition of these tissues. On the other side of the patient there is a circular system of X-ray sensors, each of which converts radiation energy into electrical signals. After amplification, these signals are converted into a digital code, which is stored in the computer's memory. The recorded signals reflect the degree of attenuation of the X-ray beam in any one direction.

Rotating around the patient, the X-ray emitter “views” his body from different angles, for a total of 360°. By the end of the rotation of the emitter, all signals from all sensors are recorded in the computer memory. The duration of rotation of the emitter in modern tomographs is very short, only 1-3 s, which makes it possible to study moving objects.

Along the way, the density of the tissue is determined by separate areas, which is measured in conventional units - Hounsfield units (HU). The density of water is taken as zero. Bone density is +1000 HU, air density is -1000 HU. All other fabrics human body occupy an intermediate position (usually from 0 to 200-300 HU).

Unlike a conventional X-ray, which best shows bones and air-bearing structures (lungs), computed tomography (CT) also clearly shows soft tissues (brain, liver, etc.), this makes it possible to diagnose diseases in the early stages , for example, to detect a tumor while it is still small and amenable to surgical treatment.

With the advent of spiral and multispiral tomographs, it became possible to perform computed tomography of the heart, blood vessels, bronchi, and intestines.

Benefits of X-ray computed tomography (CT):

H high tissue resolution - allows you to evaluate the change in the radiation attenuation coefficient within 0.5% (in conventional radiography - 10-20%);

There is no overlap of organs and tissues - there are no closed areas;

H allows you to assess the ratio of organs in the area under study

A package of application programs for processing the resulting digital image allows you to obtain additional information.

Disadvantages of computed tomography (CT):

There is always a small risk of developing cancer from overexposure. However, the possibility of an accurate diagnosis outweighs this minimal risk.

There are no absolute contraindications to computed tomography (CT). Relative contraindications to computed tomography (CT): pregnancy and early childhood, which is associated with radiation exposure.

Types of computed tomography

Spiral X-ray computed tomography (SCT).

The principle of operation of the method.

Spiral scanning consists of rotating the X-ray tube in a spiral and simultaneously moving the table with the patient. Spiral CT differs from conventional CT in that the speed of table movement can be different depending on the purpose of the study. At higher speeds, the scanning area is larger. The method significantly reduces procedure time and reduces radiation exposure to the patient's body.

The principle of operation of spiral computed tomography on the human body. Images are obtained using the following operations: The required width of the X-ray beam is set in the computer; The organ is scanned with an X-ray beam; Sensors catch pulses and convert them into digital information; Information is processed by computer; The computer displays information on the screen in the form of an image.

Advantages of spiral computed tomography. Increasing the speed of the scanning process. The method increases the area of study for more a short time. Reducing the radiation dose to the patient. The ability to obtain a clearer and higher-quality image and detect even the most minimal changes in body tissues. With the advent of new generation tomographs, the study of complex areas has become accessible.

Spiral computed tomography of the brain shows the vessels and all components of the brain with detailed accuracy. Also a new achievement was the ability to study the bronchi and lungs.

Multislice computed tomography (MSCT).

In multislice tomographs, X-ray sensors are located around the entire circumference of the installation and the image is obtained in one rotation. Thanks to this mechanism, there is no noise, and the procedure time is reduced compared to the previous type. This method is convenient when examining patients who cannot remain motionless for a long time (small children or patients in critical condition). Multispiral is an improved type of spiral. Spiral and multispiral tomographs make it possible to perform studies of blood vessels, bronchi, heart and intestines.

Operating principle of multislice computed tomography. Advantages of the multislice CT method.

H High resolution, allowing even minor changes to be seen in detail.

H Speed of research. Scanning does not exceed 20 seconds. The method is good for patients who are unable to remain motionless for a long time and who are in critical condition.

H Unlimited possibilities for studies of patients in in serious condition who need constant contact with a doctor. The ability to construct two-dimensional and three-dimensional images that allow you to obtain the most complete information about the organs being studied.

No noise during scanning. Thanks to the device’s ability to complete the process in one revolution.

Ch Radiation dose has been reduced.

CT angiography

CT angiography provides a layer-by-layer series of images of blood vessels; Based on the data obtained, a three-dimensional model of the circulatory system is built through computer post-processing with 3D reconstruction.

5. Angiography

Angiography is a method of contrast X-ray examination of blood vessels. Angiography studies the functional state of blood vessels, circuitous blood flow and the extent of the pathological process.

Angiogram of cerebral vessels.

Arteriogram

Arteriography is performed by puncture of the vessel or its catheterization. Puncture is used to study the carotid arteries, arteries and veins lower limbs, abdominal aorta and its large branches. However, the main method of angiography at present is, of course, catheterization of the vessel, which is performed according to the technique developed by the Swedish doctor Seldinger

The most common procedure is catheterization of the femoral artery.

All manipulations during angiography are carried out under X-ray television control. A contrast agent is injected under pressure through a catheter into the artery being examined using an automatic syringe (injector). At the same moment, high-speed X-ray imaging begins. The photographs are developed immediately. Once the test is successful, the catheter is removed.

Most common complication angiography - the development of a hematoma in the catheterization area, where swelling appears. A severe but rare complication is peripheral artery thromboembolism, the occurrence of which is indicated by limb ischemia.

Depending on the purpose and site of administration of the contrast agent, aortography, coronary angiography, carotid and vertebral arteriography, celiacography, mesentericography, etc. are distinguished. To perform all these types of angiography, the end of a radiopaque catheter is inserted into the vessel being examined. The contrast agent accumulates in the capillaries, causing the intensity of the shadow of the organs supplied by the vessel under study to increase.

Venography can be performed by direct and indirect methods. In direct venography, a contrast agent is introduced into the blood by venipuncture or venosection.

Indirect contrasting of veins is carried out in one of three ways: 1) by introducing a contrast agent into the arteries, from which it reaches the veins through the capillary system; 2) injection of a contrast agent into the bone marrow space, from which it enters the corresponding veins; 3) by introducing a contrast agent into the parenchyma of the organ by puncture, while the pictures show the veins draining blood from of this body. There are a number of special indications for venography: chronic thrombophlebitis, thromboembolism, post-thrombophlebitic changes in the veins, suspected abnormal development of venous trunks, various disorders venous blood flow, including due to insufficiency of the valvular apparatus of the veins, wounds of the veins, conditions after surgical interventions on the veins.

A new technique for x-ray examination of blood vessels is digital subtraction angiography (DSA). It is based on the principle of computer subtraction (subtraction) of two images recorded in the computer memory - images before and after the introduction of a contrast agent into the vessel. Here, add an image of the vessels from the general image of the part of the body being studied, in particular, remove interfering shadows of soft tissues and skeleton and quantitatively assess hemodynamics. Less radiopaque contrast agent is used, so vascular images can be obtained with a large dilution of the contrast agent. This means that it is possible to inject a contrast agent intravenously and obtain a shadow of the arteries on a subsequent series of images without resorting to catheterization.

To perform lymphography, a contrast agent is injected directly into the lumen of the lymphatic vessel. The clinic currently performs mainly lymphography of the lower extremities, pelvis and retroperitoneum. A contrast agent - a liquid oil emulsion of an iodide compound - is injected into the vessel. X-rays of the lymphatic vessels are taken after 15-20 minutes, and X-rays of the lymph nodes - after 24 hours.

RADIONUCLIDE RESEARCH METHOD

The radionuclide method is a method of studying the functional and morphological state of organs and systems using radionuclides and indicators labeled with them. These indicators - they are called radiopharmaceuticals (RP) - are introduced into the patient’s body, and then, using various instruments, the speed and nature of their movement, fixation and removal from organs and tissues are determined.

In addition, pieces of tissue, blood and secretions of the patient can be used for radiometry. Despite the introduction of negligible amounts of the indicator (hundredths and thousandths of a microgram) that do not affect the normal course of life processes, the method has extremely high sensitivity.

When choosing a radiopharmaceutical for research, the doctor must first of all take into account its physiological orientation and pharmacodynamics. It is imperative to take into account the nuclear physical properties of the radionuclide included in its composition. To obtain images of organs, only radionuclides emitting Y-rays or characteristic x-rays are used, since these radiations can be recorded by external detection. The more gamma quanta or X-ray quanta are formed during radioactive decay, the more effective a given radiopharmaceutical is in diagnostic terms. At the same time, the radionuclide should emit as little as possible corpuscular radiation - electrons that are absorbed in the patient’s body and do not participate in obtaining images of organs. Radionuclides whose half-life is several tens of days are considered long-lived, several days - medium-lived, several hours - short-lived, several minutes - ultra-short-lived. There are several ways to obtain radionuclides. Some of them are formed in reactors, some in accelerators. However, the most common method for obtaining radionuclides is generator, i.e. production of radionuclides directly in the laboratory of radionuclide diagnostics using generators.

A very important parameter of a radionuclide is the energy of electromagnetic radiation quanta. Quanta of very low energies are retained in tissues and, therefore, do not reach the detector of a radiometric device. Quanta of very high energies partially pass through the detector, so the efficiency of their registration is also low. The optimal range of quantum energy in radionuclide diagnostics is considered to be 70-200 keV.

All radionuclide diagnostic studies are divided into two large groups: studies in which radiopharmaceuticals are introduced into the patient’s body - in vivo studies, and studies of blood, pieces of tissue and patient secretions - in vitro studies.

LIVER SCINTIGRAPHY - carried out in static and dynamic modes. In the static mode, the functional activity of the cells of the reticuloendothelial system (RES) of the liver is determined, in the dynamic mode - the functional state of the hepatobiliary system. Two groups of radiopharmaceuticals (RPs) are used: to study liver RES - colloidal solutions based on 99mTc; for the study of hepatobiliary compound based on imidodiacetic acid 99mTc-HIDA, mezide.

HEPATOSCINTIGRAPHY is a technique for visualizing the liver using a scintigraphic method on a gamma camera in order to determine the functional activity and amount of functioning parenchyma when using colloidal radiopharmaceuticals. 99mTc colloid is administered intravenously with an activity of 2 MBq/kg. The technique allows you to determine the functional activity of reticuloendothelial cells. The mechanism of radiopharmaceutical accumulation in such cells is phagocytosis. Hepatoscintigraphy is performed 0.5-1 hour after administration of the radiopharmaceutical. Planar hepatoscintigraphy is performed in three standard projections: anterior, posterior and right lateral.

This is a technique for visualizing the liver using a scintigraphic method on a gamma camera to determine the functional activity of hepatocytes and the biliary system using a radiopharmaceutical based on imidodiacetic acid.

HEPATOBILISTICINTIGRAPHY

99mTc-HIDA (mesida) is administered intravenously with an activity of 0.5 MBq/kg after the patient is laid down. The patient lies on his back under a gamma camera detector, which is installed as close as possible to the surface of the abdomen so that the entire liver and part of the intestine are in its field of view. The study begins immediately after intravenous administration of the radiopharmaceutical and lasts 60 minutes. Simultaneously with the introduction of radiopharmaceuticals, recording systems are turned on. At the 30th minute of the study, the patient is given a choleretic breakfast (2 raw chicken yolks). Normal hepatocytes quickly take up the drug from the blood and excrete it with bile. The mechanism of radiopharmaceutical accumulation is active transport. The passage of the radiopharmaceutical through the hepatocyte normally takes 2-3 minutes. The first portions of it appear in the common bile duct after 10-12 minutes. At 2-5 minutes, the scintigrams show the hepatic and common bile duct, and after 2-3 minutes - the gallbladder. Maximum radioactivity over the liver is normally recorded approximately 12 minutes after administration of the radiopharmaceutical. By this time, the radioactivity curve reaches its maximum. Then it takes on the character of a plateau: during this period, the rates of uptake and removal of radiopharmaceuticals are approximately balanced. As the radiopharmaceutical is excreted in the bile, the radioactivity of the liver decreases (by 50% in 30 minutes), and the intensity of radiation above the gallbladder increases. But very little radiopharmaceuticals are released into the intestines. To induce emptying of the gallbladder and assess the patency of the bile ducts, the patient is given a choleretic breakfast. After this, the image of the gallbladder progressively decreases, and an increase in radioactivity is recorded above the intestines.

Radioisotope study of the kidneys and urinary tract radioisotope scintigraphy biliary liver.

It consists of assessing renal function, it is carried out on the basis of a visual picture and quantitative analysis of the accumulation and excretion of radiopharmaceuticals by the renal parenchyma secreted by the tubular epithelium (Hippuran-131I, Technemag-99mTc) or filtered by the renal glomeruli (DTPA-99mTc).

Dynamic renal scintigraphy.

A technique for visualizing the kidneys and urinary tract using a scintigraphic method on a gamma camera in order to determine the parameters of accumulation and elimination of nephrotropic radiopharmaceuticals through the tubular and glomerular elimination mechanisms. Dynamic renoscintigraphy combines the advantages of simpler techniques and has greater capabilities due to the use of computer systems for processing the obtained data.

Kidney scan

It is used to determine the anatomical and topographical features of the kidneys, the localization of the lesion and the extent of the pathological process in them. Based on the selective accumulation of 99mTc - cyton (200 MBq) by normally functioning kidney parenchyma. They are used when there is a suspicion of a volumetric process in the kidney caused by malignant tumor, cyst, cavern, etc., to identify congenital kidney anomalies, select the extent of surgical intervention, and assess the viability of the transplanted kidney.

Isotope renography

It is based on external registration of g-radiation over the kidney area from intravenous 131I - hippuran (0.3-0.4 MBq), which is selectively captured and excreted by the kidneys. Indicated in the presence of urinary syndrome (hematuria, leukocyturia, proteinuria, bacteriuria, etc.) pain syndrome V lumbar region, pastosity or swelling on the face, legs, kidney injury, etc. Allows you to give a separate assessment for each kidney of the speed and intensity of secretory and excretory functions, determine the patency of the urinary tract, and by blood clearance - the presence or absence of renal failure.

Radioisotope study of the heart, myocardial scintigraphy.

The method is based on assessing the distribution in the heart muscle of an intravenously administered radiopharmaceutical, which is incorporated into intact cardiomyocytes in proportion to coronary blood flow and metabolic activity of the myocardium. Thus, the distribution of the radiopharmaceutical in the myocardium reflects the state of coronary blood flow. Areas of the myocardium with normal blood supply create a picture of uniform distribution of the radiopharmaceutical. Areas of the myocardium with limited coronary blood flow due to various reasons are defined as areas with reduced radiotracer uptake, that is, perfusion defects.

The method is based on the ability of radionuclide-labeled phosphate compounds (monophosphates, diphosphonates, pyrophosphate) to be included in mineral metabolism and accumulate in the organic matrix (collagen) and the mineral part (hydroxylapatite) bone tissue. The distribution of radiophosphates is proportional to blood flow and the intensity of calcium metabolism. Diagnosis of pathological changes in bone tissue is based on visualization of foci of hyperfixation or, less commonly, defects in the accumulation of labeled osteotropic compounds in the skeleton.

5. Radioisotope study of the endocrine system scintigraphy thyroid gland

The method is based on visualization of functioning thyroid tissue (including abnormally located) using radiopharmaceuticals (Na131I, technetium pertechnetate), which are absorbed by the epithelial cells of the thyroid gland along the pathway of inorganic iodine uptake. The intensity of inclusion of radionuclide tracers in the gland tissue characterizes its functional activity, as well as individual sections of its parenchyma (“hot” and “cold” nodes).

Scintigraphy of the parathyroid glands

Scintigraphic visualization of pathologically altered parathyroid glands is based on the accumulation of diagnostic radiopharmaceuticals in their tissue, which have an increased tropism for tumor cells. Detection of enlarged parathyroid glands is carried out by comparing scintigraphic images obtained with maximum accumulation of the radiopharmaceutical in the thyroid gland (thyroid phase of the study) and with its minimum content in the thyroid gland with maximum accumulation in the pathologically altered parathyroid glands (parathyroid phase of the study).

Breast scintigraphy (mammoscintigraphy)

Diagnosis of malignant neoplasms of the mammary glands is carried out by a visual picture of the distribution in the gland tissue of diagnostic radiopharmaceuticals, which have an increased tropism for tumor cells due to the increased permeability of the histohematic barrier in combination with a higher cell density and higher vascularization and blood flow, compared with unchanged breast tissue ; peculiarities of metabolism of tumor tissue - increased activity of membrane Na+-K+ ATPase; expression of specific antigens and receptors on the surface of the tumor cell; increased protein synthesis in a cancer cell during proliferation in a tumor; phenomena of degeneration and cell damage in breast cancer tissue, due to which, in particular, the content of free Ca2+, products of damage to tumor cells and intercellular substance is higher.

The high sensitivity and specificity of mammoscintigraphy determine the high predictive value of the negative conclusion of this method. Those. the absence of accumulation of the radiopharmaceutical in the studied mammary glands indicates the probable absence of tumor viable proliferating tissue in them. In this regard, according to the world literature, many authors consider it sufficient not to perform a puncture study on a patient if there is no accumulation of 99mTc-Technetril in the “doubtful” nodule. pathological education, but only observe the dynamics of the condition for 4 - 6 months.

Radioisotope study of the respiratory system

Lung perfusion scintigraphy

The principle of the method is based on visualization of the capillary bed of the lungs using technetium-labeled albumin macroaggregates (MAA), which, when administered intravenously, embolize a small part of the lung capillaries and are distributed proportionally to the blood flow. MAA particles do not penetrate into the lung parenchyma (interstitially or alveolarly), but temporarily occlude capillary blood flow, while 1:10,000 of the pulmonary capillaries are embolized, which does not affect hemodynamics and ventilation of the lungs. Embolization lasts for 5-8 hours.

Ventilation of the lungs with aerosol

The method is based on inhalation of aerosols obtained from radiopharmaceuticals (RPs), quickly eliminated from the body (most often a solution of 99m-Technetium DTPA). The distribution of radiopharmaceuticals in the lungs is proportional to regional pulmonary ventilation; increased local accumulation of radiopharmaceuticals is observed in places of air flow turbulence. The use of emission computed tomography (ECT) makes it possible to localize the affected bronchopulmonary segment, which on average increases the diagnostic accuracy by 1.5 times.

Alveolar membrane permeability

The method is based on determining the clearance of a radiopharmaceutical solution (RP) 99m-Technetium DTPA from the entire lung or an isolated bronchopulmonary segment after aerosol ventilation. The rate of removal of radiopharmaceuticals is directly proportional to the permeability of the pulmonary epithelium. The method is non-invasive and easy to perform.

Radionuclide diagnostics in vitro (from the Latin vitrum - glass, since all studies are carried out in test tubes) refers to microanalysis and occupies a borderline position between radiology and clinical biochemistry. The principle of the radioimmunological method is the competitive binding of the desired stable and similar labeled substances with a specific perceptive system.

The binding system (most often these are specific antibodies or antiserum) interacts simultaneously with two antigens, one of which is the desired one, the other is its labeled analogue. Solutions are used that always contain more labeled antigen than antibodies. In this case, a real struggle between labeled and unlabeled antigens for connection with antibodies takes place.

In vitro radionuclide analysis began to be called radioimmunological, since it is based on the use of immunological antigen-antibody reactions. Thus, if an antibody rather than an antigen is used as the labeled substance, the analysis is called immunoradiometric; if tissue receptors are taken as the binding system, they say orradioreceptor analysis.

Radionuclide research in vitro consists of 4 stages:

1. The first stage is mixing the biological sample being analyzed with reagents from the kit containing antiserum (antibodies) and a binding system. All manipulations with solutions are carried out with special semi-automatic micropipettes; in some laboratories they are carried out using automatic machines.

2. The second stage is incubation of the mixture. It continues until dynamic equilibrium is achieved: depending on the specificity of the antigen, its duration varies from several minutes to several hours and even days.

3. The third stage is the separation of free and bound radioactive matter. For this purpose, the sorbents included in the kit are used (ion exchange resins, carbon, etc.), which precipitate heavier antigen-antibody complexes.

4. The fourth stage is radiometry of samples, construction of calibration curves, determination of the concentration of the desired substance. All this work is performed automatically using a radiometer equipped with a microprocessor and a printing device.

Ultrasound research methods.

Ultrasound examination (ultrasound) is a diagnostic method based on the principle of reflection of ultrasonic waves (echolocation) transmitted to tissues from a special sensor - an ultrasound source - in the megahertz (MHz) ultrasound frequency range, from surfaces with different permeability for ultrasonic waves . The degree of permeability depends on the density and elasticity of the tissue.

Ultrasonic waves are elastic vibrations of a medium with a frequency that lies above the range of sounds audible to humans - above 20 kHz. The upper limit of ultrasonic frequencies can be considered 1 - 10 GHz. Ultrasound waves are non-ionizing radiation and, in the range used in diagnostics, do not cause significant biological effects

To generate ultrasound, devices called ultrasound emitters are used. The most widespread are electromechanical emitters based on the phenomenon of the inverse piezoelectric effect. The inverse piezoelectric effect consists of mechanical deformation of bodies under the influence of electric field. The main part of such an emitter is a plate or rod made of a substance with well-defined piezoelectric properties (quartz, Rochelle salt, ceramic material based on barium titanate, etc.). Electrodes are applied to the surface of the plate in the form of conductive layers. If an alternating electrical voltage from a generator is applied to the electrodes, the plate, thanks to the inverse piezoelectric effect, will begin to vibrate, emitting a mechanical wave of the corresponding frequency.

Branch services

The RCT office offers the following range of studies:

Multislice computed tomography (MSCT) of the brain.
MSCT of the neck organs.
MSCT of the larynx in 2 stages (before and during phonation).
MSCT of the paranasal sinuses in 2 projections.
MSCT of the temporal bones.
MSCT of the chest organs.
MSCT of the abdominal cavity and retroperitoneal space (liver, spleen, pancreas, adrenal glands, kidneys and urinary system).
MSCT of the pelvis.
MSCT of the skeleton segment (including shoulder, knee, hip joints, hands, feet), facial skull (orbit).
MSCT of spinal column segments (cervical, thoracic, lumbar).
MSCT of discs lumbar region spinal column (L3-S1).
MSCT osteodensitometry.
MSCT virtual colonoscopy.
MSCT planning of dental implantation.
MSCT angiography (thoracic, abdominal aorta and its branches, pulmonary arteries, intracranial arteries, arteries of the neck, upper and lower extremities).
studies with intravenous contrast (bolus, multiphase).
3D, multiplanar reconstructions.
Recording the study on CD/DVD.

When conducting studies with intravenous contrast, the non-ionic contrast agent Omnipaque (manufactured by Amersham Health, Ireland) is used.
Research results are processed on a workstation using multiplanar, 3D reconstruction, and virtual endoscopy.
Patients receive study results on a CD or DVD. If the results of previous studies are available, a comparative analysis (including digital) and an assessment of the dynamics of changes are carried out. The doctor draws up a conclusion,, if necessary, conducts a consultation on the results, and gives recommendations on further research.

Equipment

The BrightSpeed 16 Elite multislice computed tomograph is a development by GE that combines a compact design and the most modern technologies.
The BrightSpeed CT scanner produces up to 16 high-resolution slices per revolution of the tube. Minimum cut thickness 0.625 mm.

X-ray

The X-ray department is equipped with the latest digital equipment, which allows for a high-quality examination to reduce the dose of X-ray radiation.
The results of the examination are given to patients on laser film, as well as CD/DVD discs.
X-ray examination makes it possible to detect tuberculosis, inflammatory diseases, and oncopathology.

Branch services

The department carries out all types of x-ray examinations:

X-ray of the chest, stomach, colon;
X-ray of the chest, bones, spine with functional tests, feet for flat feet, examination of the kidneys and urinary tract;
tomography of the chest, larynx, and bones;
dental photographs and orthopontamograms;
examination of the mammary glands, standard mammography, targeted, targeted with magnification - in the presence of microcalcifications;
pneumocystography to examine the inner wall of a large cyst;
contrast study of the milk ducts - ductography;
tomosynthesis of mammary glands.

The department also performs X-ray densitometry:

lumbar spine in direct projection;
lumbar spine in direct and lateral projection with morphometric analysis;
proximal part femur;
proximal femur with endoprosthesis;
forearm bones;
brushes;
of the whole body.

Radiation diagnostics and radiation therapy are two components of radiology. In modern medical practice they are used more and more often. This can be explained by their excellent information content.

Radiation diagnostics is a practical discipline that studies the use of various types of radiation for the purpose of detection and recognition large quantity diseases. It helps to study the morphology and functions of normal and diseased organs and systems of the human body. There are several types of radiation diagnostics, and each of them is unique in its own way and allows you to detect diseases in different areas of the body.

Radiation diagnostics: types

Today, there are several methods of radiation diagnostics. Each of them is good in its own way, as it allows you to conduct research in a certain area of the human body. Types of radiation diagnostics:

X-ray diagnostics.
Radionuclide research.
CT scan.
Thermography.

These X-ray diagnostic methods can provide data about the patient's health status only in the area they examine. But there are more advanced methods that provide more detailed and extensive results.

Modern diagnostic method

Modern radiation diagnostics is one of the rapidly developing medical specialties. It is directly related to the general progress of physics, mathematics, computer technology, and computer science.

Radiation diagnostics is a science that uses radiation to help study the structure and functioning of normal and disease-damaged organs and systems of the human body in order to prevent and recognize diseases. This diagnostic method plays a role important role both in the examination of patients and in radiological treatment procedures, which depend on the information obtained during the studies.

Modern methods of radiation diagnostics make it possible to identify pathology in a specific organ with maximum accuracy and help find the best way to treat it.

Types of diagnostics

Innovative diagnostic methods include a large number of diagnostic visualizations and differ from each other in the physical principles of data acquisition. But the common essence of all techniques lies in the information that is obtained by processing transmitted, emitted or reflected electromagnetic radiation or mechanical vibrations. Depending on which of the phenomena form the basis of the resulting image, radiation diagnostics is divided into the following types of studies:

X-ray diagnostics is based on the ability to absorb X-rays by tissues.
It is based on the reflection of a beam of directed ultrasonic waves in tissues towards the sensor.
Radionuclide - characterized by the emission of isotopes that accumulate in tissues.
The magnetic resonance method is based on the emission of radio frequency radiation, which occurs during the excitation of unpaired atomic nuclei in a magnetic field.
Infrared ray research is the spontaneous emission of infrared radiation by tissues.

Each of these methods makes it possible to accurately identify pathology in human organs and gives a greater chance of a positive treatment outcome. How does radiation diagnostics reveal pathology in the lungs, and what can be detected with its help?

Lung examination

Diffuse lung damage is changes in both organs, representing scattered foci, an increase in tissue volume, and in some cases, a combination of these two conditions. Thanks to X-ray and computer research methods, it is possible to identify pulmonary diseases.

Only modern methods Research allows you to quickly and accurately establish a diagnosis and begin surgical treatment in a hospital setting. In our time modern technologies Radiation diagnostics of the lungs is of great importance. It is very difficult to make a diagnosis according to the clinical picture in most cases. This is explained by the fact that lung pathologies are accompanied by severe pain, acute respiratory failure and hemorrhage.

But even in the most severe cases, emergency radiation diagnostics comes to the aid of doctors and patients.

In what cases is research indicated?

The X-ray diagnostic method allows you to quickly identify a problem when a patient’s life-threatening situation arises that requires urgent intervention. Urgent x-ray diagnosis can be useful in many cases. Most often it is used for damage to bones and joints, internal organs and soft tissues. Injuries to the head and neck, abdomen and abdominal cavity, chest, spine, hip and long tubular bones are very dangerous for humans.

The X-ray examination method is prescribed to the patient immediately after anti-shock therapy is carried out. It can be carried out directly in the emergency department, using a mobile device, or the patient is taken to the x-ray room.

For neck and head injuries, a survey X-ray is taken, and if necessary, special images are added individual parts skulls In specialized institutions, rapid angiography of cerebral vessels can be performed.

In case of injury to the chest, the diagnosis begins with an overview and is done with a direct and lateral view. In case of injuries to the abdomen and pelvis, it is necessary to conduct an examination using contrast.

Urgent care is also carried out for other pathologies: acute abdominal pain, coughing up blood and bleeding from the digestive tract. If the data is not enough to establish an accurate diagnosis, a computed tomography scan is prescribed.

X-ray diagnostics are rarely used in cases of suspected presence of foreign bodies in the respiratory tract or digestive tract.

For all types of injuries and in complex cases, it may be necessary to conduct not only a computed tomography scan, but also a magnetic resonance imaging scan. Only the attending doctor can prescribe this or that test.

Advantages of radiodiagnosis

This research method is considered one of the most effective, therefore, considering its advantages, I would like to highlight the following:

Under the influence of rays, tumor tumors decrease, some die cancer cells, and the remaining ones stop dividing.
Many of the vessels from which food is supplied become overgrown.
The biggest benefits come from treating certain types of cancer: lung, ovarian and thymus.

But not only does this method have positive aspects, there are also negative ones.

Disadvantages of radiation diagnostics

Most doctors believe, no matter how amazing this research method is, their negative sides he also has. These include:

Side effects that occur during therapy.
Low sensitivity to radioactive radiation of organs such as cartilage, bones, kidneys and brain.
Maximum sensitivity of the intestinal epithelium to this irradiation.

Radiation diagnostics has shown good results in identifying pathology, but it is not suitable for every patient.

Contraindications

This research method is not suitable for all patients with cancer. It is prescribed only in certain cases:

The presence of a large number of metastases.
Radiation sickness.
Ingrowth of cancerous roots into the largest vessels and organs of the reproductive system.
Fever.
The patient's severe condition with severe intoxication.
Extensive cancerous lesion.
Anemia, leukopenia, and thrombocytopenia.
Disintegration of cancerous tumors with bleeding.

Conclusion

Radiation diagnostics has been used for several years and has shown very good results in quickly making diagnoses, especially in complex cases. Thanks to its use, it was possible to determine diagnoses for very seriously ill patients. Even despite its shortcomings, there are no other studies that would give such results. Therefore, we can say for sure that radiation diagnostics is currently in first place.

The problems of disease are more complex and difficult than any other that a trained mind has to solve.

A majestic and endless world spreads out around. And every person is also a world, complex and unique. In different ways we strive to explore this world, to understand the basic principles of its structure and regulation, to understand its structure and functions. Scientific knowledge is based on the following research techniques: morphological method, physiological experiment, clinical research, radiation and instrumental methods. However scientific knowledge- only the first basis for diagnosis. This knowledge is like sheet music for a musician. However, using the same notes, different musicians achieve different effects when performing the same piece. The second basis of diagnosis is art and personal experience doctor“Science and art are as interconnected as the lungs and the heart, so if one organ is perverted, then the other cannot function correctly” (L. Tolstoy).

All this emphasizes the exclusive responsibility of the doctor: after all, every time at the patient’s bedside he makes an important decision. Constantly increasing knowledge and the desire for creativity are the traits of a real doctor. “We love everything - the heat of cold numbers, and the gift of divine visions...” (A. Blok).

Where does any diagnostics begin, including radiation? With deep and solid knowledge about the structure and functions of the systems and organs of a healthy person in all the uniqueness of his gender, age, constitutional and individual characteristics. “For a fruitful analysis of the work of each organ, it is necessary first of all to know its normal activity” (I.P. Pavlov). In this regard, everything Chapter III parts of the textbook begin with a summary of the radiation anatomy and physiology of the relevant organs.

Dream I.P. Pavlov's concept of capturing the majestic activity of the brain with a system of equations is still far from being realized. With a majority pathological processes diagnostic information is so complex and individual that it is not yet possible to express it with a sum of equations. Nevertheless, repeated consideration of similar typical reactions allowed theorists and clinicians to identify typical syndromes of injuries and diseases and to create some images of diseases. This is an important step on the diagnostic path, therefore, in each chapter, after a description of the normal picture of the organs, the symptoms and syndromes of diseases that are most often detected during radiation diagnostics are considered. Let us only add that it is here that the personal qualities doctor: his observation and ability to discern the leading syndrome of the lesion in a motley kaleidoscope of symptoms. We can learn from our distant ancestors. We mean the rock paintings of the Neolithic times, which surprisingly accurately reflect the general scheme (image) of the phenomenon.

In addition, each chapter provides a brief description of the clinical picture of a few of the most common and severe diseases that the student should become familiar with both in the department of radiation diagnostics and

ki and radiation therapy, and in the process of supervising patients in therapeutic and surgical clinics in senior years.

The actual diagnosis begins with an examination of the patient, and it is very important to choose the right program for its implementation. The leading link in the process of disease recognition, of course, remains qualified clinical examination, but it is no longer limited to examining the patient, but is an organized, purposeful process that begins with an examination and includes the use of special methods, among which radiation occupies a prominent place.

In these conditions, the work of a doctor or group of doctors should be based on a clear program of action, which provides for the procedure for applying in various ways research, i.e. every doctor should be armed with a kit standard circuits examination of patients. These schemes are designed to provide high reliability diagnostics, saving effort and money for specialists and patients, priority use of less invasive interventions and reducing radiation exposure to patients and medical personnel. In this regard, each chapter provides radiation examination schemes for certain clinical and radiological syndromes. This is only a modest attempt to outline the path to comprehensive radiological examination in the most common clinical situations. The further task is to move from these limited schemes to genuine diagnostic algorithms that will contain all the data about the patient.

In practice, alas, the implementation of the examination program is associated with certain difficulties: the technical equipment of medical institutions varies, the knowledge and experience of doctors, and the patient’s condition are different. “Wits say that the optimal trajectory is the trajectory along which the rocket never flies” (N.N. Moiseev). Nevertheless, the doctor must choose for a particular patient the best way examinations. The marked stages are included in the general scheme diagnostic study patient.

History data and clinical picture of the disease

Establishing indications for radiation examination

Choosing a radiation examination method and preparing the patient

Carrying out radiation examination

Analysis of an organ image obtained using radiation methods

Analysis of organ function carried out using radiation methods

Comparison with the results of instrumental and laboratory studies

Conclusion

In order to effectively conduct radiation diagnostics and competently evaluate the results of radiation studies, it is necessary to adhere to strict methodological principles.

First principle: Any radiological examination must be justified. The main argument in favor of performing a radiation procedure should be the clinical need to obtain additional information, without which a complete individual diagnosis cannot be established.

Second principle: when choosing a research method, it is necessary to take into account the radiation (dose) load on the patient. The guidelines of the World Health Organization stipulate that X-ray examination must have undoubted diagnostic and prognostic effectiveness; otherwise, it is a waste of money and poses a health hazard due to the unnecessary use of radiation. If the information content of the methods is equal, preference should be given to the one that does not expose the patient to radiation or is the least significant.

Third principle: When conducting radiation research, you must adhere to the “necessary and sufficient” rule, avoiding unnecessary procedures. The procedure for performing the necessary research- from the most gentle and unburdensome to the more complex and invasive (from simple to complex). However, we must not forget that sometimes it is necessary to immediately perform complex diagnostic interventions due to their high information content and importance for planning the treatment of the patient.

Fourth principle: When organizing radiation research, it is necessary to take into account economic factors (“cost effectiveness of methods”). When starting to examine a patient, the doctor is obliged to anticipate the costs of its implementation. The cost of some radiation examinations is so high that their unreasonable use can affect the budget of a medical institution. We put the benefit for the patient first, but at the same time we do not have the right to ignore the economics of medical treatment. Not taking it into account means organizing the work of the radiation department incorrectly.

Science is the best modern way satisfying the curiosity of individuals at the expense of the state.

Radiation diagnostic methods and their characteristics. Radiation diagnostics. Radiation diagnostic methods

Advantages and disadvantages

Methods and techniques

Photo gallery

X-ray diagnostics

Radionuclide diagnostics

Ultrasound diagnostics

Magnetic resonance imaging

Thermography

Microwave thermometry

Magnetic resonance spectrometry

Interventional radiology

Types and use of radiocontrast agents in radiology diagnostics

In what cases is radiodiagnosis indicated?

Contraindications

Where is radiation diagnostics used?

In pediatrics

In dentistry

In cardiology and neurology

In traumatology and orthopedics

Respiratory diseases

In gastroenterology

In urology and neurology

For emergencies

During pregnancy

Send your good work in the knowledge base is simple. Use the form below

Similar documents

Branch services

Branch services

Radiation diagnostics: types

Modern diagnostic method

Types of diagnostics

Lung examination

In what cases is research indicated?

Advantages of radiodiagnosis

Disadvantages of radiation diagnostics

Contraindications

Conclusion