The cosmic radiation of the Earth, as well as man-made and natural radionuclides, are involved in the formation of the radiation background. Background radiation is radiation from man-made and natural sources, under the influence of which a person is.

General information

After the Chernobyl disaster, about 40 types of artificial radionuclides were released into the atmosphere. Substances such as strontium, cesium, plutonium, and iodine pose the greatest danger to humans. The half-life of some of them reaches 25 thousand years.

According to the organization that deals with environmental problems, radionuclides are recognized as the most toxic substances. For a long time, nuclear test sites existed on the territory of the former USSR, where nuclear weapons were tested and hazardous waste was stored. The most famous are "Mayak" and the training ground in the city of Semipalatinsk.

Sources of radioactive radiation

A person receives a dose of radiation from external, cosmic sources, also under the influence of internal radionuclides in the body. The average dose of radiation from external and internal exposure to sources is about 200 mrem/year.

Human industrial activity directly affects the formation of radionuclides and isotopes in the atmosphere. They are extracted from the bowels of the earth in the process of extracting coal, oil, gas, mineral fertilizers.

Exposure to natural radionuclides is possible even at home. Materials such as brick, wood, concrete emit small amounts of radon.

Being in an unventilated room for a long time, a person runs the risk of receiving a large dose of this radionuclide. Potassium-40, radium-226, polonium-210, radon-222, -220 have a negative impact on health.

The degree of impact of cosmic radiation on a person depends on the area in which he lives. People living in the mountains have a higher exposure risk than those living in the lowlands. It is known that those who live low above sea level receive about 300 µSv/year. The reason for this is the screening properties of water. The average volume of radiation coming from space to which a person is exposed per year is 350 μSv.

Radiation background and its types

The radiation background of natural origin includes cosmic radiation, as well as natural radionuclides that fill the water surface, the earth's crust, and the atmosphere as a whole. Its value remained unchanged for many thousands of years. There are several areas where the magnitude of human exposure to radiation is much higher. This is explained by the fact that thorium or uranium ore lies shallow in the soil, radon springs come out.

The natural radiation background is radiation that comes from outer space, as a result of the processing of radioactive elements located in the bowels of the Earth, in building materials, food. The radionuclides 40К and 222Rn represent the greatest danger. The natural radiation background was formed and developed simultaneously with the development of the biosphere. Cosmogenic radionuclides participated in the formation of the Earth's crust. Shifts and depressions in it are places where radionuclides were released to the earth's surface, the power of ionizing radiation increased. Over time, the degree of radioactivity decreased.

The natural radiation background can become technologically modified due to the transformation of ionizing radiation. Artificial radiation background is a consequence of the decay of nuclear waste energy.

The degree of exposure to artificial sources of radiation is illustrated in the table:

Human activity as a source of manifestation of radiation

Since the middle of the 20th century, the level of radiation from technogenic impact has increased to 15 μR/h. This happened for a number of reasons:

• testing of nuclear weapons;
• combustion of fossil fuels;
• redistribution of minerals that are mined from the earth;
• emissions of harmful substances due to accidents at nuclear power plants and enterprises.

Technogenic sources include various sources of penetrating radiation:

• medical diagnostic devices;
• x-ray equipment;
• energy and research installations;
• radiation flaw detection.

As a result of nuclear reactions, transuranium radionuclides are formed. They are highly toxic. The most dangerous are plutonium, americium.

According to the degree of toxicity, radionuclides are divided into 4 groups:

• especially high toxicity;
• high toxicity;
• average toxicity;
• low toxicity (do not pose a serious danger to humans).

Radiation exposure measurement

The concept of "radiation background norm" appeared in the 20s of the last century. The level of permissible exposure was at around 600 mSv/year. By the middle of the 20th century, this value dropped to 50 mSv/year, and in 1996, 20 mSv/year. The norm indicator was introduced for the examination of medical staff, especially radiologists.

Man experiences the influence of radiation everywhere. A radioactive dose in a certain amount is always present in the body. When the norm of radiation in the body is exceeded many times, death can occur.

Permissible radiation rate for a person (natural background exposure) ranges from 0.05 µSv/h to 0.5 µSv/h. It is especially dangerous to be exposed to man-made radiation in large volumes. Radionuclides and isotopes accumulate in the human body, causing diseases, primarily cancer.

The radiation level is the maximum allowable dosage of the background level of ionizing radiation (measured in microsieverts). The permissible level of radiation in a closed room is 25 microR/h. The unit of radiation emission is microsieverts per hour. The probability of developing cancer rises sharply if a person is exposed to a dose of radiation above 11.42 µSv/h. More than half of people exposed to a dose of more than 570.77 µSv at a time die in 3-4 weeks. The maximum permissible level of radiation from sources of natural origin is considered normal within the limits of up to 0.57 μSv / h. The normal radiation background, excluding the influence of radon, is 0.07 microns/hour.

Radiation is of particular danger to persons whose professional activities involve constant exposure to radiation. Measures to prevent exposure among medical staff are reduced to the establishment of an acceptable radiation limit.

The maximum allowable concentration (MAC) of radioactive radiation is calculated based on data on the type and period of decay of ionizing particles.

If a person regularly comes into contact with radioactive elements, he needs to know how to protect himself. Permissible levels of contamination of clothing and protective equipment after disinfection have been developed and put into practice. The maximum allowable contamination level is shown in the table below.

There is an average daily allowance for a person. It is equal to 0.0027 mlSv/day.

The danger of exposure to radiation on the body

Normal background radiation does not harm human life and health. The most detrimental effects of radiation exposure include somatic diseases, as well as genetic ones, which are reflected at the DNA level.

It has been established that systematic irradiation has a more sparing effect on the human body than a single one, since radiation damage tends to recover.

Hazardous substances accumulate in the body unevenly. The immune system is suppressed under the influence of radionuclides, which is reflected in the increased susceptibility of a person to certain diseases, especially oncological ones. The digestive and respiratory systems suffer the most. Radionuclides come through them first of all. The concentration of absorbed harmful substances in them is 2-3 times higher than in other organs. Normally, the safe level of background radiation is 50 μR/hour.

Large Russian cities and metropolitan areas are characterized by an increased background of radiation. This is due to the consequences of the Chernobyl accident, the movement of radioactive dust, the continuous operation of large industrial enterprises, emissions from transport and thermal power plants. The detrimental consequences of exposure to radiation for a person are the deterioration of health, the development of cancer, various mutations at the gene level, which lead to a general decrease in the quality of life.

Radiological types of examination in medicine still play a leading role. Sometimes, without data, it is impossible to confirm or make a correct diagnosis. Every year, techniques and X-ray technology are improving, becoming more complicated, becoming safer, but, nevertheless, the harm from radiation remains. Minimizing the negative impact of diagnostic exposure is a priority task for 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 effect 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, in simple terms - "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 of 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.

A single exposure that a patient receives during conventional radiography increases the risk of developing a 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 background is when 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 of 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 emit 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 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 provide for photographing the body area, but for 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, for 15 minutes of chest X-ray, the total dose of radiation received can be from 2 to 3.5 mSv.

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

Computed tomography 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.

A comparison of effective doses of radiation received during the most commonly used diagnostic types of studies in medicine, and doses received daily by a person from the environment, is 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.

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1 milliroentgen per hour [mR/h] = 1000 microroentgen per hour [µR/h]

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 a special type of 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 of radiation 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 currently 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 of normal functioning of cells, such violations 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 these experiments were carried out at test sites and designated areas for testing nuclear weapons, such as the Nevada test site in the United States, the Novaya Zemlya nuclear test site in what is now Russia, and the Semipalatinsk test site in what is now 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. Basically, the main purpose of these experiments was to see 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 a large dose of 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 the negative effects of radiation. Skin, bones, and muscle tissues are less affected, and the least effect of radiation is 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 the protective 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 at an early 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 an important indicator of exposure 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 to radiation on the body does not harm 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 amount of radiation but with a higher power, in a shorter period 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, because 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, airline pilots and 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

The norm of radiation for a person, or the permissible dose of radiation, is an average value in μR / h, obtained through a clinical study of patients whose body has been exposed to ionizing radiation. As a result of scientific research, it was found that, for example, a certain dose of radiation can reflect conditional norms or violations, the degree of ionization, the intensity and capacity of absorption, and equivalence calculated by special coefficients. The level of normal radiation for a person is just the permissible limit of radiation in μR / h, at the threshold of which changes in the body begin.

Close to nuclear power plant

Are all types of radiation dangerous?

Several special terms are used to define ionizing radiation because it can come from different sources. This term refers to any streams formed by photons, elementary particles or fragments of atoms that can ionize a substance. The following should be noted:

1. Ionization is the process of formation of ions (positively or negatively charged) from molecules or atoms. The result of this interaction is the absorption of heat and the emission of electrons.
2. They ionize the matter they hit. Penetrating into cellular structures, they destroy and destabilize them. A dangerous result of this action is a failure of immunity, the cessation of the usual chemical exchanges that ensure the vital activity of the cell and are called natural metabolism.
3. By causing the release of free electrons, this decay forms free radicals. The intensity of the reaction and the provocation of the release of greater or lesser intensity and determines what is commonly referred to as the level of radiation.
4. Not all types of radiation are dangerous for humans. Some can become so under certain conditions, but usually they do not have enough energy to cause ionization.
5. Ultraviolet and infrared rays, visible light and radio bands cannot cause ionization in the normal (basic) state.
6. Studies have shown that electromagnetic and X-ray, particle flows of various types (for example, neutrons, protons, alpha particles or ions, as a result of nuclear fission) can become a source of radiation radiation.

When people talk about radiation, they mean ionizing radiation.

It triggers the destruction of proteins, causes the destruction of the cells of a living organism or their degeneration. In nature, there are natural sources of such streams, but man also participated to a large extent in the emergence of potential reservoirs from which dangerous particles can appear.

/ Physical health

Sievert, millisievert and microsievert

Measurement of radiation power and received dose during dental radiography.

Prevention of radioactive delusions - 2

Since the discovery of x-rays the attitude towards their use and, in general, the existence of our people, and not ours, changed polarly - from radiohysteria to radiophobia. At first, the passion for radiology among the more or less literate population of the planet was quite common. In laboratory conditions, it is not so difficult to mount a primitive tube emitting cathode rays, and at the beginning of the last century, not only doctors, but also all kinds of healers, magicians and charlatans began to use X-rays for their own purposes. Naturally, without any protection and understanding of the nature of this phenomenon. The consequences were not long in coming. There were reports of lesions of the skin, bones, and it turned out that the cause of their occurrence was the thoughtless use of primitive X-ray generators. People began to treat this matter with caution and alertness. Then there was the war, the Japanese and Americans with their bombs. In general, in the eyes of the public, Hiroshima completely spoiled the image of radiation exposure to the body. The period of radiophobia began.

However, with the development of science, high technology and against the backdrop of a general wiser people slowly calmed down. In the West, even the so-called radiation hormesis theory. Its essence lies approximately in the fact that if large doses of radiation have an adverse effect on living organisms - they inhibit cell division, growth and development, then small doses, on the contrary, stimulate almost all physiological processes.

Where did this opinion come from? Well, firstly, now it's no secret to anyone that there is a natural radiation background and this is the same integral and integral part of nature as air, water and sunlight. You can't live without it. Or rather, it is possible, but the mice, isolated from any background influence, feel much worse than their free counterparts. That is, for the body, the effect of a natural radiation background is something like a "free" energy supply. A short-term and one-time increase in the background stimulates many processes responsible for the functioning of the immune system and cell renewal. There is also a version that in ancient times the background was many times higher and, due to mutagenic effects, many different earthly creatures were formed. Then the background dropped sharply and over the past ten thousand years, Mother Nature has failed to create a single new hare or birch. Like that.

This theory also has ardent opponents, and there are much more of them than supporters. These opponents adhere to the concept linear non-threshold effect of radiation(LBE), according to which there are no harmless doses, any are harmful, but in different ways. There is a limit set by nature, and everything that is above is already superfluous, which means it is harmful. Developed the concept of a Swedish physicist Sievert, he also came up with an effective equivalent dose, for which he was immortalized as its unit.

Where does background radiation come from?

First of all, the general background must be divided into natural and unnatural man-made. Technogenic, of course, factories, factories, plus electrification of the whole country and a TV in every home. And, of course, medicine. On average, medical research accounts for up to a quarter of total annual exposure.

In turn, the sources of radiation that determine the natural background are, no matter how trite it sounds - heaven and earth. All conceivable and inconceivable types of radiation fly at us from space, capable of incinerating all living things in their path. However, filtering through the atmosphere (especially through the long-suffering ozone layer), what gets to the earth gets to the ground and we do not feel any impact. Radon gas, a product of the decay of radioactive elements, is constantly rising from the ground towards us. These elements are in different quantities under the entire surface of the earth and radon is emitted everywhere and constantly - both in Antarctica under penguins, and in Africa under pygmies, and right now from our basement. Therefore, in stuffy basements, the radiation background is always higher than in the attic. Many, probably, paid attention that in bourgeois films, when they show the basements of skyscrapers, there are always big scary fans there - this is how they fight radon. In this regard, we have a simpler one: radon is not ammonia, it doesn’t sting the eye, it doesn’t hit the nose, which means it doesn’t seem to exist. That's how we live.

Since radiation does not smell, its presence has to be determined and measured using a variety of dosimetric equipment. Some individuals sometimes claim that they feel changes in their body even with the slightest and short-term change in the radiation background, for example, after orthopantomography. It is safe to say that this is not any kind of hypersensitivity, but simply hysteria or lies. In Hiroshima - there, of course, yes, everyone felt it sharply, but here - not the case.

For measuring radiation power and received dose There are many different units, but our population, as a rule, does not distinguish these units among themselves, and everything that is connected with radiation is measured in "roentgens". x-rays we radiate, receive, grab, they fly, form and accumulate. It should be said right away that the roentgen is now considered an off-system unit and instead of it, the "Coulomb per kilogram" - C / kg is officially used. However Pendant, due to its non-roundness, the unit is very inconvenient and therefore, for various kinds of calculations, the use of the unit of x-ray is still allowed. In general, an x-ray is such an amount of radiation, under the influence of which 2.08x10 9 pairs of ions are formed in 1 cubic centimeter of air. And that's it. The rest is not X-ray.

In roentgens, the amount of generated radiation or exposure dose is measured. That is, this is the amount of energy that, one might say, flew out in your direction, and should fall if nothing is protected. What has fallen and can no longer be washed off is called the absorbed dose and is measured in Grays.

Gray is 1 joule of energy per 1 kg of live weight. According to the old one, 1 Gy is equal to 100 rad (Radiation Absorbed Dose) and is obtained when exposed to an exposure dose of 100 roentgens. However, glad, like rem(biological equivalent of X-ray) - also off-system units and are not used now. Instead, Sievert is used.

What is Sievert

Now, if 1 Gray of radiant energy fell on a person (God forbid, of course!) Then, penetrating into the tissue, the beam is weakened due to tissue absorption. As a result, roughly speaking, from the whole "joule per kilogram" that fell on the skin, taking into account the coefficient of tissue attenuation, 0.85 remains. But already inside, in the tissues - this is Sievert. The dose measured in Sieverts is called equivalent, that is, corresponding to a certain type of radiation (a, b, y, X-R).

However, for X-rays, the absorbed and equivalent doses are considered equal. The energy received in the tissue does a certain amount of work and can cause any effect in the body. To assess possible effects, both immediate and probable distant (stochastic), the concept of effective equivalent dose is used. It is determined based on the impact on the entire body by finding the average of the equivalent doses received by the twelve most problematic places in the body. These "places" are: gonads, mammary and thyroid glands, red bone marrow, lungs, adrenal glands, the surface of the nearest bone tissue and 5 more areas most affected by this type of study. In our case, these are the tongue, eye, salivary glands, lens and pituitary gland.

So what exactly is 1 Sievert?

This is such an effective equivalent dose that is obtained with an absorbed dose of 1 Gy. And what is 1 Gray - a lot or a little? If you put 100 normal healthy men and give each one a Gray at a time, then there is a high probability that half of them will get radiation sickness. In other words, an absorbed dose of 1 Gy in 50% of cases causes the development of radiation sickness in its various manifestations. Treatment at this dose occurs spontaneously. An absolutely lethal dose for humans is 6 Gy. Therefore, Gray, or the same Sievert, is a very large dose. If you do not participate in the elimination of radiation disasters, do not undergo radiation therapy for a tumor and do not try to create an atomic bomb in a shed, you can hardly get such a dose somewhere just like that. Therefore, smaller units are more widely used.

Dividing 1 sievert by 1000 gives us a millisievert. That is, 1 mSv is one thousandth of a Sievert.

How much is 1 millisievert

If you remove the man-made background and climb into the most environmentally friendly area where they do not do fluorography, do not stink of stokers and do not mine uranium, the natural background there will be approximately 0.5-1.0 millisievert per year (1 mSv). The maximum allowable background value for human life is 5 mSv per year. If we take the planet as a whole, then the average natural background is 2 mSv. However, "average temperature in the hospital" does not mean at all that it is equally cool in all wards. In the Chernobyl zone, in one of the many Bolivian Sao Paulo and somewhere in southern Africa, the background overflows all conceivable borders and - nothing, people live. In short - 1 millisievert per year is such a dose that is considered absolutely safe when added to the average natural background, and that is how much we are allotted for a year for X-rays, according to SANPIN and NRB. But, millisievert, again, the value is quite large. For example, conventional film fluorography provides a dose of about 0.5-0.8 mSv. Therefore, we divide the millisievert by another thousand. We get - microsievert.

Microsievert - 1 µSv

It is one thousandth of a millisievert or one millionth of a sievert. That is, a film fluorogram is 500-800 µSv, and a digital fluorogram is 60 µSv. Computed tomography of the skull, made on a step-by-step tomograph, provides 1000-15000 µSv, on a modern spiral tomograph - 400-500 µSv, and on a maxillofacial tomograph with a planar sensor, such as PICASSO or ACCUITOMO - 45-60 µSv. Feel the difference.

Where can I get a dose of 1 microsievert

If you open "Taschenatlas der Zahnarztlichen Radiologie" by Friedrich Pasler and Heike Visser, better known to us in Russian translation as "X-ray diagnostics in the practice of a dentist", then somewhere in the middle of the book you can find information that a series of 20 intraoral images made using a visiograph and a modern X-ray diagnostic apparatus with a round tube provide an effective equivalent dose of 21.7 μSv. The data were officially published in Germany in 2000. That is, according to German calculations, one intraoral image of the tooth corresponds to approximately one microsievert. That, it would seem, is all. But, having an inquisitive mind, a harmful character and a history aggravated by Chernobyl, one can try to doubt.

Measure standard effective equivalent dose with the help of anthropomorphic phantoms. This is a doll made of a material with an absorption coefficient similar to that of human soft tissues (for example, wax or rubber). Dosimeters are placed in places where a person has the above organs, a picture of the area under study is taken, then the readings are read and the average is taken. It would seem - what is easier. But, as it turned out, we have big problems with phantoms in our country. There are many different ones, but you will not find just such ones in the daytime with fire. So it is not so easy to measure reliably the equivalent effective dose for each type of modern radiography. You can, of course, try to negotiate with the morgue ... But it's better to start with a theory.

Based on the knowledge that 75% of the radiant energy goes directly in the direction of the beam, especially when the object and the generator are close, it can be argued that when examining the teeth of the upper and lower jaws, a person receives completely different radiation exposure.

X-ray of the teeth of the lower jaw, the beam is directed almost parallel to the ground or even from the bottom up, that is, to the back of the head, to the top of the head, to the cheek, in general, most of the vital organs and other genitalia remain far to the side.

And vice versa, when examining the teeth of the upper jaw the beam is directed for the most part from top to bottom, that is, exactly behind the collar, where all this good is usually located.

In those distant times, when therapeutic dentistry was simple and unambiguous, like soldier's underwear, Stavitsky R.V. calculated doses just at the dental appointment during radiography using Aktobe X-ray diagnostic devices 5D-1 and 5D-2. Judging by his figures, the patient received from these generators (and still receives in some places) and the Soviet film 29-47 μSv in one shot when X-raying the teeth of the upper jaw and 13-28 μSv of the lower. That is, the load in the study of the teeth of the upper jaw is almost 2 times higher than when working with the lower one. The same proportion is observed in the recommendations of some manufacturers of modern equipment regarding highly sensitive film - 8-12 µSv in the upper jaw and 4-7 µSv in the lower jaw. If we take into account that the load during digital radiography is on average 3 times lower than with film, then, according to rough estimates, the load when working with a radiovisiograph is obtained at a maximum of 4 μSv for the upper jaw and 2 μSv for the lower.

In general, according to the Germans, it turns out that in the 1 millisievert allocated to us for irradiation, we can put a thousand intraoral images of the teeth (of course, taking into account the fact that the patient will not undergo fluorography and other heavy radiation examinations during the current year), but according to our rough estimates - 250-300. Do you need that much? Of course not!

The nuances to remember

So far, we have been talking about an effective equivalent dose based on the whole body, however, due to the specifics of the examination, the equivalent dose received by the gonads and salivary glands differs hundreds of times! The tongue, salivary glands and lens receive the greatest load during dental radiography. The load on the remaining organs is either identical or less than the effective equivalent dose given above. The equivalent dose for the tongue is 8 times higher than the effective one, the salivary glands - 4 times, and the lens 1.25 times.

At the same time, it makes no difference - 1 µSv or 5 µSv - these are doses of negligibly small doses. A person receives five microsieverts after three hours of sitting in front of an ordinary TV and does not "steam" at all about this. The concept of "low doses" begins after 100,000 µSv, since the first minimal movements in the body and negative reactions to radiation, which can be immediately detected in the laboratory, begin at a dose of 100 millisieverts.

In general, you should not apply to your peaceful dentistry such concepts that are used at a nuclear test site. Everything is much simpler and brighter. It is clear that in connection with the Chernobyl tragedy, radiophobia for our people is almost a national trait, but here, again, this is not the case. Of course, you can bend any stick - even the smallest generator weighs about a pound, and if the head of the device accidentally unscrews, you can beat off your legs. And to the question of the patient "What dose did I receive?" - you can answer in a kind voice: "Small. Very small!". And don't fool anyone! So, follow the safety precautions, act according to the instructions and everything will be fine!

D.V.Rogatskin, radiologist,
Prevention magazine, #3-2008

Orthopantomography

OPTG, or the so-called panoramic x-ray. In a few minutes, the device produces an overview image of the entire oral cavity. This x-ray provides information about the teeth, upper and lower jaw bones, sinuses, and other hard and soft tissues of the head and neck.

Orthopantomography, photo medpulse.ru

Panoramic x-rays are an important part of a complete dental examination. It is desirable to do it once every five to seven years. While it doesn't show many of the details that other types of x-rays show on teeth and gums, it does help prevent most potential diseases.

Liliana Lokatskaya

For reference

Millisieverts of nuclear scientists and liquidators

• 50 millisieverts is the annual maximum permissible exposure dose for operators at nuclear facilities in "peacetime".
• 250 millisieverts is the maximum allowable emergency exposure dose for professional liquidators. After receiving such a dose, a person usually needs to be treated. He should never again be allowed to work at nuclear power plants or other radiation hazardous facilities.
• 300 mSv - this level causes signs of radiation sickness.
• 4000 mSv is radiation sickness with a probability of death, i.e. of death.
• 6000 mSv - the death of an irradiated person within a few days.

1 millisievert (mSv) = 1000 microsieverts (µSv).