How many times a year can an adult take an x-ray. Possible risks: how many times a year you can take an x-ray for a child. What affects the outcome of the study. Natural radiation background

X-ray types examinations in medicine continue to play a leading role. Sometimes without data it is impossible to confirm or deliver correct diagnosis. Every year, techniques and X-ray technology are improving, becoming more complicated, becoming safer, but, nevertheless, the harm from radiation remains. minimization negative impact diagnostic radiation is a priority task of radiology.

Our task is to understand the existing numbers of radiation doses, their units of measurement and accuracy at a level accessible to any person. Also, let's touch on the reality of possible health problems that this type of medical diagnosis can cause.

What is x-ray radiation

X-ray radiation is a stream of electromagnetic waves with a wavelength between ultraviolet and gamma radiation. Each type of wave has its own specific influence on the human body.

At its core, X-rays are ionizing. It has a high penetrating power. Its energy is a danger to humans. The harmfulness of radiation is the higher, the greater the dose received.

About the dangers of exposure to x-rays on the human body

Passing through the tissues of the human body, X-rays ionize them, changing the structure of molecules, atoms, plain language- "charging" them. The consequences of the radiation received can manifest themselves in the form of diseases in the person himself (somatic complications), or in his offspring (genetic diseases).

Each organ and tissue is differently affected by radiation. Therefore, radiation risk coefficients have been created, which can be found in the picture. The higher the value of the coefficient, the higher the susceptibility of the tissue to the action of radiation, and hence the risk of complications.

The blood-forming organs, the red bone marrow, are the most exposed to radiation.

The most common complication that appears in response to irradiation is blood pathology.

A person has:

• reversible changes in blood composition after minor exposures;
• leukemia - a decrease in the number of leukocytes and a change in their structure, leading to malfunctions in the body's activity, its vulnerability, and a decrease in immunity;
• thrombocytopenia - a decrease in the content of platelets, blood cells responsible for clotting. This pathological process can cause bleeding. The condition is aggravated by damage to the walls of blood vessels;
• hemolytic irreversible changes in the composition of the blood (decomposition of red blood cells and hemoglobin), as a result of exposure to powerful doses radiation;
• erythrocytopenia - a decrease in the content of erythrocytes (red blood cells), causing the process of hypoxia (oxygen starvation) in tissues.

Friendiepathologistsand:

• the development of malignant diseases;
• premature aging;
• damage to the lens of the eye with the development of cataracts.

Important: X-ray radiation becomes dangerous in case of intensity and duration of exposure. Medical equipment uses low-energy irradiation of short duration, therefore, when used, it is considered relatively harmless, even if the examination has to be repeated many times.

The single exposure that a patient receives from a conventional x-ray increases the risk of developing malignant process in the future by about 0.001%.

note: unlike the impact of radioactive substances, the harmful effect of the rays stops immediately after the device is turned off.

The rays cannot accumulate and form radioactive substances, which then will be independent sources of radiation. Therefore, after an x-ray, no measures should be taken to “remove” radiation from the body.

In what units are the doses of received radiation measured?

It is difficult for a person who is far from medicine and radiology to understand the abundance of specific terminology, the numbers of doses and the units in which they are measured. Let's try to bring the information to a clear minimum.

So, what is the dose of X-ray radiation measured in? There are many units of radiation measurement. We will not analyze everything in detail. Becquerel, curie, rad, gray, rem - this is a list of the main quantities of radiation. They are used in various measurement systems and areas of radiology. Let us dwell only on practically significant in X-ray diagnostics.

We will be more interested in x-ray and sievert.

A characteristic of the level of penetrating radiation emitted by an X-ray machine is measured in a unit called "roentgen" (R).

To assess the effect of radiation on a person, the concept is introduced equivalent absorbed dose (EPD). In addition to EPD, there are other types of doses - all of them are presented in the table.

Equivalent absorbed dose (in the picture - Effective Equivalent Dose) is a quantitative value of the energy that the body absorbs, but this takes into account the biological response of body tissues to radiation. It is measured in sieverts (Sv).

A sievert is approximately comparable to 100 roentgens.

The natural background radiation and the doses given out by medical X-ray equipment are much lower than these values, therefore, the values ​​\u200b\u200bof a thousandth (milli) or one millionth (micro) Sievert and Roentgen are used to measure them.

In numbers it looks like this:

• 1 sievert (Sv) = 1000 millisievert (mSv) = 1000000 microsievert (µSv)
• 1 roentgen (R) \u003d 1000 milliroentgen (mR) \u003d 1000000 milliroentgen (mR)

To estimate the quantitative part of the radiation received per unit of time (hour, minute, second), the concept is used - dose rate, measured in Sv/h (sievert-hour), µSv/h (micro-sievert-h), R/h (roentgen-hour), µr/h (micro-roentgen-hour). Similarly - in minutes and seconds.

It can be even simpler:

• total radiation is measured in roentgens;
• the dose received by a person is in sieverts.

Radiation doses received in sieverts accumulate over a lifetime. Now let's try to find out how much a person receives these very sieverts.

Natural radiation background

The level of natural radiation is different everywhere, it depends on the following factors:

• altitude above sea level (the higher, the harder the background);
• geological structure of the area (soil, water, rocks);
• external reasons - the material of the building, the presence of a number of enterprises that give additional radiation exposure.

Note:the most acceptable is the background at which the radiation level does not exceed 0.2 μSv / h (micro-sievert-hour), or 20 μR / h (micro-roentgen-hour)

The upper limit of the norm is considered to be up to 0.5 μSv / h = 50 μR / h.

For several hours of exposure, a dose of up to 10 µSv/h = 1 mR/h is allowed.

All types X-ray studies fit into the safe standards of radiation exposure, measured in mSv (millisieverts).

Permissible radiation doses for a person accumulated over a lifetime should not exceed 100-700 mSv. Actual exposure values ​​for people living in high mountains may be higher.

On average, a person receives a dose equal to 2-3 mSv per year.

It is summed up from the following components:

• radiation of the sun and cosmic radiation: 0.3 mSv - 0.9 mSv;
• soil and landscape background: 0.25 - 0.6 mSv;
• radiation from housing materials and buildings: 0.3 mSv and above;
• air: 0.2 - 2 mSv;
• food: from 0.02 mSv;
• water: from 0.01 - 0.1 mSv:

In addition to the external dose of radiation received, the human body also accumulates its own deposits of radionuclide compounds. They also represent a source of ionizing radiation. For example, in bones this level can reach values ​​from 0.1 to 0.5 mSv.

In addition, there is exposure to potassium-40, which accumulates in the body. And this value reaches 0.1 - 0.2 mSv.

note: to measure the radiation background, you can use a conventional dosimeter, for example RADEX RD1706, which gives readings in sieverts.

Forced diagnostic doses of X-ray exposure

The value of the equivalent absorbed dose for each x-ray examination can vary significantly depending on the type of examination. The radiation dose also depends on the year of manufacture of medical equipment, the workload on it.

Important: modern x-ray equipment gives radiation ten times lower than the previous one. We can say this: the latest digital X-ray technology is safe for humans.

But still, we will try to give the average figures for the doses that a patient can receive. Let's pay attention to the difference between the data produced by digital and conventional X-ray equipment:

• digital fluorography: 0.03-0.06 mSv, (the most modern digital devices give radiation at a dose of 0.002 mSv, which is 10 times lower than their predecessors);
• film fluorography: 0.15-0.25 mSv, (old fluorographs: 0.6-0.8 mSv);
• radiography of the chest cavity: 0.15-0.4 mSv .;
• dental (tooth) digital radiography: 0.015-0.03 mSv., conventional: 0.1-0.3 mSv.

In all of the above cases we are talking about one picture. Studies in additional projections increase the dose in proportion to the frequency of their conduct.

The fluoroscopic method (which does not involve photographing the body area, but a visual examination by a radiologist on the monitor screen) gives significantly less radiation per unit of time, but the total dose may be higher due to the duration of the procedure. So, in 15 minutes of fluoroscopy of organs chest the total dose of radiation received can be from 2 to 3.5 mSv.

Diagnostics of the gastrointestinal tract - from 2 to 6 mSv.

CT scan uses doses from 1-2 mSv to 6-11 mSv, depending on the organs being examined. The more modern the X-ray machine is, the lower the doses it gives.

Separately, we note radionuclide diagnostic methods. One procedure based on a radiopharmaceutical yields a total dose of 2 to 5 mSv.

Comparison effective doses radiation received during the most commonly used diagnostic types of studies in medicine, and doses received daily by a person from the environment, are presented in the table.

Important:Magnetic resonance imaging does not use x-rays. In this type of study, an electromagnetic pulse is sent to the area being diagnosed, which excites the hydrogen atoms of the tissues, then the response that causes them is measured in the formed magnetic field with a high intensity level.Some people mistakenly classify this method as an x-ray.

Radiography is a method of functional diagnostics of the human body using x-rays. Such studies are of two types: sighting and review. In the first case, a small area of ​​the human body is subjected to research. In the second case, a large area of ​​\u200b\u200bthe human body is examined: the head, chest or limbs.

One of the modern methods for diagnosing the state of cartilage and bone tissue, using special equipment, is a knee x-ray method. For a complete and accurate assessment existing pathologies or injuries, you can take a picture in the following projections:

• Straight. It is prescribed to diagnose the presence of fractures.
• Tangential. It is prescribed for suspected chronic joint disease.
• Side. It is prescribed for the diagnosis of ligament rupture and general assessment of the joint.
• Transcondylar projection. It is prescribed for suspected rupture of ligaments, aseptic necrosis, osteoarthritis.

Usually, an x-ray of the knee joint when contacting traumatology or orthopedics is necessary if a condylar fracture is suspected femur, tuberosity fracture tibia and condyles, neck fracture fibula or the head of the bone, with a fracture or dislocation of the patella. Radiography of the knee joint in 2 projections: direct and lateral, is performed during a standard examination.

Straight X-ray is performed in the following sequence:

• The patient is placed on his back.
• Puts the legs straight.
• The leg to be photographed is placed perpendicular to the table.

Lateral X-ray is performed in the following sequence:

• The patient is placed on the side.
• The affected leg is placed underneath and bent at the knee.

Image of a healthy knee joint

If you take a picture healthy joint in direct projection, you can see the articular ends of the tibia and femur. Fragments and cracks on the surface of the bone will not be visible. The bone density will also be uniform. The surfaces of the ends of the bones will also correspond to each other. The joint space on both sides will also be symmetrical, without inclusions and outgrowths.

What can a knee x-ray show?

The joint gap on the sighting picture will look wide, as if there is a void between the bones. This illusion arises due to the fact that the X-ray beam passes through cartilage tissue covering the articular surfaces, without obstruction.

In the picture, the cartilage itself will not be visible, but its changes are determined by the underlying end plates of the joint.

If you do an x-ray of the knee, you can identify the following pathologies:

• Arthritis or arthrosis of the joint. These diseases can be seen in lesions articular cartilage: thinning or thickening of the end articular plates.
• dislocation or traumatic injury joint. In this case, several shots are taken with a frequency between them to control the treatment.
• Congenital joint changes.
• To detect tumors.

Depending on the detected disease, pictures of the knee are taken in one or two projections. A targeted x-ray or lateral x-ray with a bent knee is ordered by a doctor if a fracture is suspected. This method remains relevant, despite more modern diagnostic methods.

Indications for a knee x-ray

The x-ray is indispensable for joint injuries or disease research. This method is used to track the dynamics of changes as a result of treatment, as well as for primary diagnosis.

This diagnostic method is shown:

This method not only shows changes in the bones, but also the presence of fluid in the joints. It is much easier to get rid of the disease with early detection of pathology.

Contraindications

Radiography has its contraindications, like all medical research, in the following cases:

• Pregnancy at all stages.
• Schizophrenia and others mental disorders during the period of exacerbation.
• Severe condition of the patient.
• Severe obesity (with this disease, the picture is distorted).
• The presence of bolts and metal prostheses in the knee.
• Existing radiation sickness.

After the X-ray examination, it is not recommended to plan the conception of children for men within three months, and for women within one. In cases of frequent appointment of this type of examination, it is recommended to use green tea, milk and natural juices with pulp.

Taking one picture of the knee joint, a person receives a radiation dose equal to the daily dose of radiation when using a mobile phone. Modern equipment allows you to receive a lower dose of radiation.

Joint changes

When examining the knee, the doctor prescribes an x-ray as a primary examination. Depending on the purpose of the study, an x-ray is prescribed in a direct or lateral projection. On the pictures you can see:

In osteoarthritis of the knee, an X-ray examination is most often prescribed. With this examination, the doctor can qualitatively assess changes in bone tissue. When examining pathologies of soft tissues and cartilage, an alternative method of ultrasound is used. The same method is most often used in children, as it is more gentle.

How and where to get a knee x-ray

X-rays can be taken at any medical center that is equipped with modern apparatus. To get the correct result, you should take a referral from your doctor in advance. The picture is taken without prior preparation on the day of treatment or by appointment. At the place of residence, you can go through this procedure for free. In private clinics, the cost varies depending on the complexity of the examination and averages from 1,100 to 2,000 rubles.

Your doctor will help you place your foot on the table and take a picture. In order for the picture to be clear and not blurry, you need to hold your breath for a few seconds and not move. Correct posture the patient is also reflected in the quality of the picture.

To obtain a picture in a direct projection, the patient should take a position lying on his back. Such images are used to detect various diseases. Two additional examinations in an aiming or lateral projection are usually prescribed after an injury. The quality of the image itself often depends on the qualifications of the doctor.

Purpose of contrast radiography

Cartilage and ligaments are almost invisible on a conventional x-ray. To this end, the doctor may prescribe contrast radiography. To make such an examination, air is injected into the joint and contrast agent. The cavity fills and increases in size, after which cartilage and ligaments can be seen in the picture.

Such a study is prescribed in cases where:

• Articular pathology is suspected.
• They want to identify an old injury to the ligaments or joint.
• The presence of a tumor is suspected.
• They want to identify the presence of intra-articular pathology (presence of a foreign body).

This procedure cannot be considered light examinations. After it, many patients complain of a crunch in the knee joint, and an allergic reaction may develop.

Alternative diagnostic methods

Science does not stand still and research methods are subject to constant modernization. Today, in some clinics, patients may be offered digital x-rays. It is carried out on modernized devices and the resulting image is transferred to the display.

This method is very effective for traumatology, because it helps the doctor to get a picture in as soon as possible. Such a picture can be immediately sent over the local network to the attending physician and improve its appearance.

Computed tomography is another alternative diagnostic method. This method allows surgeons to obtain much more information, although the patient receives much more radiation from this method of examination compared to conventional x-rays.

This device allows you to take pictures simultaneously in several planes without changing the position of the patient's body. The doctor saves the information received on electronic media, which allows you to quickly transfer information to the attending physician via a local or global network.

Until the 20th century, doctors had to work blindfolded. To see the internal organs of the patient - the ancient doctors dreamed about this. "Penetrating through the flesh" vision would help to understand what is happening in the patient's body, establish a more accurate diagnosis, and prescribe more effective treatment.

But for many centuries, doctors were forced to understand the causes of diseases only external symptoms. The situation changed in 1895, when the 50-year-old physicist Wilhelm Roentgen discovered a new type of radiation. X-rays made it possible for the first time to penetrate into the holy of holies of the human body - to receive "photographs" of bones, joints, and internal organs.

Despite the fact that today there are more high-tech diagnostic methods, doctors continue to actively use x-rays. This helps to get a lot of valuable and necessary information.

When do you need to do an x-ray? What diseases does it help to diagnose?

X-ray examination is one of the most commonly used imaging modalities. It is used to diagnose the most various diseases in various fields of medicine.

When a person who has been injured enters the emergency room, the first thing the doctor will do is give him an x-ray. The study helps to understand whether the bones and joints were damaged, to distinguish fractures and dislocations from less serious injury. Traumatologists use radiography to check how correctly the bone fragments were repositioned (compared), whether they were correctly installed, whether the wires, screws and other metal structures were displaced.

For dentists, radiography helps to assess the condition of the root of the tooth and the tissues that surround it, the jaw bones. ENT doctors use X-rays to assess the condition paranasal sinuses nose. Chest x-ray plays an important role in diagnosing pathologies of the heart and lungs.

X-rays are often used to diagnose diseases of the spine. It helps to identify anomalies and injuries (fractures, subluxations) of the vertebrae, assess the condition of posture, intervertebral discs, diagnose scoliosis, osteochondrosis and other diseases. This is an indispensable diagnostic method in the work of neurologists, orthopedists.

Soft tissues do not show up as well on x-rays as do bones. But they can be "painted over" with the help of special radiopaque solutions. X-ray with contrast is used to study blood vessels, organs digestive system, bronchi, kidneys and bladder.

Varieties of X-ray

The first picture of the bones of the hand, taken by Wilhelm Roentgen, became a real sensation. Doctors were able to see for the first time what is inside the human body without resorting to an autopsy. Over time, radiography has undergone great changes, its capabilities have greatly increased. In modern clinics, different types of X-ray diagnostics are used.

During X-ray contrast studies, a solution of a special substance is injected into the organ, which gives a bright shadow in the pictures and thereby contours its walls. The contrast solution can be drunk, used as an enema, injected through special catheters into the bronchi, bladder, ureters and renal pelvis, bile ducts and pancreatic ducts, into other organs. A separate type of radiopaque studies is angiography, during which a contrast solution is injected into the vessels.

Radiography can be combined with fluoroscopy - a study during which the doctor monitors the work of the organ on the screen in real time. Separate types radiography is used for screening - early diagnosis of cancer and other diseases. For example, it helps to detect pathological formations in the chest in time, mammography - in the mammary gland.

If, during the study, the radiation source and the film are moved in a special way, it is possible to obtain an image with a “slice” of the part of the body being examined on different levels. This study is called tomography. During computed tomography, X-rays are also used.

Are x-rays dangerous?

X-rays are a type of electromagnetic waves. They are emitted by electrons, which, having strongly accelerated, hit a dense material. X-ray waves are not something artificially created by man, they are natural radiation that hits the Earth with the rays of the Sun. Every person daily experiences the effects of X-rays, and even radioactive radiation, in minimal doses.

Yes, scientists classify X-rays as carcinogens, that is, factors that increase the risk of cancer. However, if X-rays are used correctly, the risks are negligible, they are not comparable with the benefits that X-rays bring.

It is better to take an x-ray if it is useful. Diagnosis and choice better way treatment outweighs the very small risk of x-rays.

Radiography is a safe diagnostic method because:

• The level of radiation in X-ray machines is strictly dosed. During the study, the patient receives a safe dose.
• Doctors prescribe a study only if it is necessary, if without it it is impossible to establish the correct diagnosis and prescribe effective treatment.
• Between x-rays withstand certain intervals of time. No doctor will prescribe you a study every day.
• Modern devices provide more low level radiation compared to older models, the body receives a minimal dose.
• If the doctor finds that you have contraindications, they will not prescribe an x-ray. Doctors always weigh potential benefits against potential risks.

Who does not use x-rays?

• First of all, radiography is contraindicated during pregnancy, since x-rays can cause unwanted mutations in the cells of the embryo. The degree of risk depends on the duration of pregnancy. Sometimes doctors still make an exception and prescribe a study for a pregnant woman.
• X-rays are not performed on patients who are in serious condition if there is severe bleeding or damage to the chest with depressurization of the pleural cavity.
• The composition of the solutions that are used for radiopaque studies includes iodine. It causes allergic reactions in some people. If the patient is allergic to iodine, contrast should not be injected.
• X-ray contrast studies are contraindicated in certain diseases of the thyroid gland, severe pathologies kidneys and liver, active tuberculosis, decompensated diabetes mellitus.

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1 roentgen per hour [R/h] = 2.77777777777778E-06 sievert per second [Sv/s]

Initial value

Converted value

gray per second exagray per second petagray per second teragray per second gigagray per second megagray per second kilogray per second hectogray per second decagray per second decigray per second centigray per second milligray per second microgray per second nanogray per second picogray per second femtogray per second attogray per second second rad per second joule per kilogram per second watt per kilogram sievert per second millisieverts per year millisieverts per hour microsieverts per hour rem per second roentgen per hour milliroentgen per hour microroentgen per hour

More about the absorbed dose rate and the total dose rate of ionizing radiation

General information

Radiation is a natural phenomenon that manifests itself in the fact that electromagnetic waves or elementary particles with high kinetic energy move inside the medium. In this case, the medium can be either matter or vacuum. Radiation is all around us, and our life without it is unthinkable, since the survival of humans and other animals without radiation is impossible. Without radiation, there will be no such natural phenomena necessary for life as light and heat on Earth. In this article, we will discuss special type radiation, ionizing radiation or the radiation that surrounds us everywhere. In what follows, in this article, by radiation we mean ionizing radiation.

Sources of radiation and its use

Ionizing radiation in an environment can arise either through natural or artificial processes. natural sources Radiations include solar and cosmic radiation, as well as radiation from certain radioactive materials such as uranium. Such radioactive raw materials are mined in the depths of the earth's interior and used in medicine and industry. Sometimes radioactive materials are released into the environment as a result of accidents at work and in industries that use radioactive raw materials. Most often, this occurs due to non-compliance with safety rules for the storage and handling of radioactive materials, or due to the lack of such rules.

It is worth noting that until recently, radioactive materials were not considered hazardous to health, and on the contrary, they were used as healing drugs, and they were also valued for their beautiful glow. uranium glass is an example of radioactive material used for decorative purposes. This glass glows fluorescent green due to the addition of uranium oxide. The percentage of uranium in this glass is relatively small and the amount of radiation emitted by it is small, so uranium glass is this moment considered safe for health. They even make glasses, plates, and other utensils from it. Uranium glass is valued for its unusual glow. The sun emits ultraviolet light, so uranium glass glows in sunlight, although this glow is much more pronounced under ultraviolet light lamps.

Radiation has many uses, from generating electricity to treating cancer patients. In this article, we will discuss how radiation affects human, animal, and biomaterial tissues and cells, focusing on how quickly and how severely radiation damage occurs to cells and tissues.

Definitions

Let's look at some definitions first. There are many ways to measure radiation, depending on what exactly we want to know. For example, one can measure the total amount of radiation in an environment; you can find the amount of radiation that disrupts the functioning of biological tissues and cells; or the amount of radiation absorbed by the body or organism, and so on. Here we will look at two ways to measure radiation.

The total amount of radiation in the environment, measured per unit of time, is called total dose rate of ionizing radiation. The amount of radiation absorbed by the body per unit of time is called absorbed dose rate. The total dose rate of ionizing radiation is easy to find using widely used measuring instruments, such as dosimeters, the main part of which is usually Geiger counters. The operation of these devices is described in more detail in the article on radiation exposure dose. The absorbed dose rate is found using information about the total dose rate and about the parameters of the object, organism, or part of the body that is exposed to radiation. These parameters include mass, density and volume.

Radiation and biological materials

Ionizing radiation has a very high energy and therefore ionizes particles of biological material, including atoms and molecules. As a result, electrons are separated from these particles, which leads to a change in their structure. These changes are caused by the fact that ionization weakens or destroys chemical bonds between particles. This damages the molecules inside cells and tissues and disrupts their function. In some cases, ionization promotes the formation of new bonds.

Violation of the cells depends on how much radiation has damaged their structure. In some cases, disturbances do not affect the functioning of cells. Sometimes the work of the cells is disrupted, but the damage is small and the body gradually restores the cells to a working condition. In the process normal operation cells, such disorders often occur and the cells themselves return to normal. Therefore, if the level of radiation is low and the disturbances are small, then it is quite possible to restore the cells to their working state. If the level of radiation is high, then irreversible changes occur in the cells.

With irreversible changes, cells either do not work as they should, or stop working altogether and die. Radiation damage to vital and irreplaceable cells and molecules, such as DNA and RNA molecules, proteins or enzymes, causes radiation sickness. Cell damage can also cause mutations that can cause genetic diseases in the children of patients whose cells are affected. Mutations can also cause cells to divide too rapidly in patients' bodies - which in turn increases the likelihood of cancer.

Conditions that exacerbate the effects of radiation on the body

It is worth noting that some studies of the effect of radiation on the body, which were carried out in the 50s - 70s. last century, were unethical and even inhumane. In particular, these are studies conducted by the military in the United States and in the Soviet Union. Most of of these experiments was carried out at test sites and in specially designated areas for testing nuclear weapons, for example, at the test site in Nevada, USA, at the nuclear test site at Novaya Zemlya in present-day Russia, and at the Semipalatinsk test site in present-day Kazakhstan. In some cases, experiments were carried out during military exercises, such as during the Totsk military exercises (USSR, in present-day Russia) and during the Desert Rock military exercises in Nevada, USA.

Radioactive releases during these experiments harmed the health of the military, as well as civilians and animals in the surrounding areas, since measures to protect against radiation were insufficient or completely absent. During these exercises, researchers, if you can call them that, studied the effects of radiation on the human body after atomic explosions.

From 1946 to the 1960s, experiments on the effect of radiation on the body were also carried out in some American hospitals without the knowledge and consent of the patients. In some cases, such experiments were even carried out on pregnant women and children. Most often, a radioactive substance was introduced into the patient's body during a meal or through an injection. Mostly main goal These experiments were to trace how radiation affects life and the processes occurring in the body. In some cases, the organs (for example, the brain) of deceased patients who received a dose of radiation during their lifetime were examined. Such studies were performed without the consent of the relatives of these patients. Most often, the patients on whom these experiments were performed were prisoners, terminally ill patients, invalids, or people from the lower social classes.

Dose of radiation

We know that large dose radiation, called acute radiation dose, causes a threat to health, and the higher this dose, the higher the risk to health. We also know that radiation affects different cells in the body in different ways. Cells that undergo frequent division, as well as those that are not specialized, suffer the most from radiation. For example, cells in the fetus, blood cells, and cells of the reproductive system are most susceptible to negative influence radiation. Skin, bones, and muscle tissues less affected, and the smallest effect of radiation on nerve cells. Therefore, in some cases, the total destructive effect of radiation on cells that are less affected by radiation is less, even if they are exposed to more radiation than cells that are more affected by radiation.

According to the theory radiation hormesis small doses of radiation, on the contrary, stimulate defense mechanisms in the body, and as a result, the body becomes stronger and less prone to disease. It should be noted that these studies are currently initial stage, and it is not yet known whether such results can be obtained outside the laboratory. Now these experiments are carried out on animals and it is not known whether these processes occur in the human body. For ethical reasons, it is difficult to obtain permission for such research involving humans, as these experiments can be dangerous to health.

Radiation dose rate

Many scientists believe that the total amount of radiation an organism has been exposed to is not the only indicator of how much radiation affects the body. According to one theory, radiation power- also important indicator radiation and the higher the radiation power, the higher the exposure and the destructive effect on the body. Some scientists who study radiation power believe that at low radiation power, even prolonged exposure radiation on the body does not cause harm to health, or that the harm to health is insignificant and does not impair vital activity. Therefore, in some situations after accidents with leakage of radioactive materials, evacuation or resettlement of residents is not carried out. This theory explains the low harm to the body by the fact that the body adapts to low-power radiation, and recovery processes occur in DNA and other molecules. That is, according to this theory, the effect of radiation on the body is not as destructive as if the irradiation occurred with the same total radiation but with higher power, in a shorter amount of time. This theory does not cover occupational exposure - in occupational exposure, radiation is considered dangerous even at low levels. It is also worth considering that research in this area has begun relatively recently, and that future research may give very different results.

It is also worth noting that according to other studies, if animals already have a tumor, then even small doses of radiation contribute to its development. This is very important information, since if in the future it is found that such processes also occur in the human body, then it is likely that those who already have a tumor will be harmed by radiation even at low power. On the other hand, at the moment we are using high power radiation to treat tumors, but only areas of the body that have cancer cells are being irradiated.

The safety rules for working with radioactive substances often indicate the maximum allowable total dose of radiation and the absorbed dose rate of radiation. For example, exposure limits issued by the United States Nuclear Regulatory Commission are calculated on an annual basis, while the limits of some other similar agencies in other countries are calculated on a monthly or even hourly basis. Some of these restrictions and rules are designed to deal with accidents in which radioactive substances are released into the environment, but often their main purpose is to create rules for the safety of the workplace. They are used to limit the exposure of workers and researchers at nuclear power plants and other enterprises where they work with radioactive substances, pilots and airline crews, medical workers, including radiologists, and others. More information about ionizing radiation can be found in the article absorbed dose of radiation.

Health Hazard Caused by Radiation

Chest X-ray is performed for diseases of the ribs and spine, as well as organs located in the chest - lungs, pleura, heart. According to statistics, a chest x-ray most often reveals rib fractures, pneumonia, and heart failure. For people of certain professions ( miners, chemical industry workers) chest x-ray is a mandatory examination and is carried out at least once a year.

How do x-rays work?

X-rays are part of the electromagnetic wave spectrum, just like visible sunlight. However, the frequency and wavelength of X-rays do not allow the human eye to distinguish between them. The invisibility of X-rays and, at the same time, their ability to leave behind an image on film, gave rise to their alternative name - X-rays.

An X-ray tube serves as the source of X-rays. When passing through the human body, X-rays are partially absorbed, and the rest of the rays pass through the human body. The amount of absorbed radiation depends on the physical density of the tissues, so the ribs and spine on a chest x-ray will retain more x-rays than the lungs. To fix the rays that have passed through the body, a screen, film or special sensors are used.

Digital and standard chest x-ray

Over time, methods of radiation diagnostics improved, methods for recording x-ray images were invented. Standard radiography is recorded on photosensitive film. This technique also has its drawbacks, as the film may fade over time. The exposure level for the patient became moderate.

Today, most medical institutions use digital x-ray machines. Such devices record data using special sensors and transmit information to a computer. The doctor can study the x-ray image directly on the monitor screen or print it on photographic paper.

Digital X-ray has the following advantages over standard X-ray:

• The quality of the resulting image. The sensors have a higher sensitivity compared to the agent with which the film is treated. As a result, the image is more contrast and sharper.
• The possibility of computer processing of x-rays. The doctor can zoom in and out of the digital image, study the negative, remove noise using software tools.
• Low radiation dose. The sensors respond to less x-ray energy than the photosensitive agent, so less x-ray power is used.
• Convenient storage of information. A digital photograph can be stored indefinitely in the computer's memory.
• Ease of transfer. Digital X-ray can be sent via e-mail which saves doctor and patient time.

How is a chest x-ray different from a chest x-ray?

The main difference between fluorography and standard radiography is that the image from the fluorescent x-ray screen is fixed on camera film. The film has dimensions of 110 x 110 mm or 70 x 70 mm. The image obtained with fluorography is reduced and inverted. The advantage of this technique is its low cost and the possibility mass application. However, if the doctor suspects a patient has a lung disease, then he will prescribe not a fluorography, but a chest x-ray due to the disadvantages that fluorography has.

The main disadvantages of fluorography before a chest x-ray include:

• low sharpness and contrast ( it is difficult to distinguish shadows smaller than 4 mm on fluorography);
• the radiation dose is 2-3 times higher;
• reduced size of the chest.

What is the difference between an X-ray and a CT scan? CT) chest?

To perform computed tomography, a circular scan of the body is performed with a narrow beam of x-rays. X-rays passing through the human body are perceived by electronic sensors. With all the advantages of digital radiography, computed tomography has the best resolution and accuracy.

The optical density of tissues is determined in conventional Hounsfield units ( HU). The optical density of water is taken as zero, the value -1000 HU corresponds to the density of air, and +1000 HU corresponds to the density of bone. Thanks to a large number intermediate values ​​using computed tomography, you can distinguish the smallest differences in tissue densities. It is believed that CT is 40 times more sensitive than conventional x-rays.

With the help of CT of the chest, any diagnosis of diseases of the lungs, bones or heart can be made with high accuracy. According to the shape and color characteristics of various pathological formations on CT, one can easily determine their origin, whether it is an abscess, a tumor, or an inflammatory infiltrate.

Indications and contraindications for chest x-ray

Indications for a chest x-ray due to lung disease

A chest x-ray due to lung disease is prescribed for the following symptoms:

• cough ( for at least a week);
• expectoration;

A chest x-ray is indicated to confirm or refute the diagnosis of the following lung diseases:

• acute and chronic bronchitis;
• pneumonia ( pneumonia);
• tuberculosis;
• lung tumors;
• pulmonary edema;
• pneumothorax;

Indications for a chest x-ray due to diseases of the heart and blood vessels

Chest X-ray is informative for the following diseases of the heart and blood vessels:

• chronic heart failure;
• heart attack and post-infarction changes in the heart;
• dilated and hypertrophic cardiomyopathy;
• congenital and acquired heart defects;
• aortic aneurysm;

Indications for a chest x-ray due to diseases of the skeletal system ( ribs and spine)

Another group of problems are diseases of the spine. Most often, patients complain of pain and limitation of movement in thoracic region spine. These symptoms accompany osteochondrosis of the spine and intervertebral hernia. Pain occurs due to infringement spinal nerves. To clarify the diagnosis of diseases of the spine, doctors prescribe computed or magnetic resonance imaging ( MRI) .

Contraindications for chest x-ray

Contraindications for a chest x-ray are:

• open bleeding;
• multiple fractures of the ribs and spine;
• severe general condition of the patient;
• children's age up to 15 years.

How long is a chest x-ray valid?

If pathological changes were detected on a chest x-ray, then x-rays with even more frequent frequency are required to monitor them. After acute pneumonia residual effects disappear only after two months, which requires a control x-ray. chronic diseases such as bronchitis or emphysema require dispensary observation and x-rays if symptoms worsen.

Technique for chest x-ray. Preparing for a chest x-ray

Who issues a referral for a chest x-ray?

A chest x-ray is performed in the direction of:

• family doctors;
• oncologists, etc.

Where is a chest x-ray performed?

The X-ray room has high parameters of anti-radiation protection. With the help of special screens, all surfaces are protected - doors, windows, walls, floor and ceiling. There may be no natural light in the x-ray room. A separate door to the X-ray room leads to a room from which radiologists remotely control the release of X-rays. In the same place, they evaluate the picture and make a conclusion on it.

In the X-ray room are:

• X-ray machine ( one or more);
• mobile screens;
• means of radiation protection ( aprons, collars, skirts, plates);
• devices that record the dose of radiation;
• means for developing or printing pictures;
• negatoscopes ( bright screens for illuminating film shots);
• desks and computers for record keeping.

What is a chest x-ray machine?

The digital X-ray unit includes:

• Source of power. It receives electrical energy from the electrical network and transforms it into electricity higher voltage. This is necessary to obtain X-ray radiation of sufficient power.
• Tripod. A digital chest x-ray is usually performed in a standing position. A touch screen is attached to a vertical tripod, adjustable in height, on one side, and an X-ray emitter on the other. During the study, the patient is between the screen and the emitter.
• X-ray emitter. Creates x-ray radiation of a given power. It has several focal lengths for studying organs located at different depths in the human body.
• collimator. This is a device that concentrates a beam of x-rays. As a result, lower radiation doses are used.
• Digital X-ray receiver. Consists of sensors that perceive X-rays and transmit them to a computer device.
• Hardware-software complex. Receives and processes information from sensors. Thanks to software the radiologist can study the digital image in detail, as it contains powerful image manipulation tools.

Who performs a chest x-ray?

After receiving an x-ray, the radiologist makes a conclusion on the picture. Despite the fact that the doctor referring to the study can independently read the x-ray, the radiologist more experience in this diagnostic method, so his opinion is considered expert.

How is a chest x-ray performed in two projections ( straight, lateral)?

Before performing an x-ray, the patient undresses to the waist and removes all metal objects. During direct projection, the patient stands between a screen containing a film cassette or digital sensors and an X-ray emitter. The chin is fixed with a special holder so that the head is parallel to the floor, and the spine takes the correct vertical position. The chest is projected into the center of the screen. The radiologist sets the X-ray emitter at the desired distance, which is usually 2 meters. After that, he goes to the office and remotely controls the release of x-rays. At this time, the patient should draw air into the lungs and hold the breath for 10-15 seconds. This is how an x-ray is obtained in a straight line ( anteroposterior) projections.

A chest x-ray in a lateral projection is carried out in a similar way. Only the position occupied by the researcher differs. The patient leans against the screen on the side of the chest that is to be x-rayed. Hands must be taken behind the head, and during the X-ray, at the command of the radiologist, you need to hold your breath.

X-ray examination is quick and does not cause any discomfort to the patient. Together with the conclusion, the entire procedure lasts 10-15 minutes. The patient does not have to worry about the radiation dose, since modern x-ray machines use low power x-rays.

How to prepare for a chest x-ray?

Computed tomography of the chest also does not require special training. The patient must be aware that he will be surrounded by a CT scanner ring, so it is important to be psychologically prepared for being in an enclosed space. As with conventional x-rays, the patient must be free of all metal objects before the CT scan is performed.

Can I eat or smoke before a chest x-ray?