(Russian designation: Gr; international: Gy). The previously used non-systemic unit rad is 0.01 Gy.

Does not reflect the biological effect of radiation (see equivalent dose).

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More about radiation

More about Radiation

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Hello. In this edition of the TranslatorsCafe.com channel, we will talk about ionizing radiation or radiation. We will consider sources of radiation, ways to measure it, the effect of radiation on living organisms. In more detail, we will talk about such radiation parameters as the absorbed dose rate, as well as the equivalent and effective doses of ionizing radiation. Radiation has many uses, from generating electricity to treating cancer patients. In this video, we will discuss how radiation affects tissues and cells in humans, animals and biomaterials, focusing on how quickly and how severely radiation damage occurs to cells and tissues. 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. There would be no mobile phones or the Internet. In this video, we will discuss a special type of radiation, ionizing radiation or radiation, which surrounds us everywhere. Ionizing radiation has energy sufficient to detach electrons from atoms and molecules, that is, to ionize the irradiated substance. Ionizing radiation in an environment can arise either through natural or artificial processes. Natural sources of radiation include solar and cosmic radiation, certain minerals such as granite, and radiation from certain radioactive materials such as uranium and even ordinary bananas containing a radioactive isotope of potassium. 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. On the contrary, they were used as healing preparations, and they were also valued for their beautiful glow. Uranium glass is an example of a radioactive material used for decorative purposes. This glass glows with a fluorescent green light due to the addition of uranium oxide to its composition. The percentage of uranium in this glass is relatively small and the amount of radiation emitted by it is small, so uranium glass is considered relatively safe for health. They even made 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. When emitted, photons of higher energy (ultraviolet) are absorbed and photons of lower energy (green) are emitted. As you have seen, these beads can be used to test dosimeters. You can buy a bag of beads on eBay.com for a couple of dollars. Let's look at some definitions first. There are many ways to measure radiation, depending on what exactly we want to know. For example, you can measure the total amount of radiation in a given location; 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 the total dose rate of ionizing radiation. The amount of radiation absorbed by the body per unit of time is called the absorbed dose rate. The absorbed dose rate is found using information about the total dose rate and the parameters of the object, organism, or part of the body that is exposed to radiation. These parameters include mass, density and volume. The absorbed and exposure dose values ​​are similar for materials and tissues that absorb radiation well. However, not all materials are like this, so often absorbed and exposed doses of radiation differ, since the ability of an object or body to absorb radiation depends on the material of which it is composed. For example, a lead sheet absorbs gamma radiation much better than an aluminum sheet of the same thickness. We know that a large dose of radiation, called the acute dose, causes a health hazard, and the higher the dose, the greater 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 non-specialized cells, 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. At the same time, skin, bones, and muscle tissues are less affected by radiation. But radiation has the least effect 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 of 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 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 human studies. Absorbed dose - the ratio of the energy of ionizing radiation absorbed in a given volume of matter to the mass of matter in this volume. The absorbed dose is the main dosimetric quantity and is measured in joules per kilogram. This unit is called gray. Previously, the off-system unit rad was used. The absorbed dose depends not only on the radiation itself, but also on the material that absorbs it: the absorbed dose of soft X-rays in bone tissue can be four times the absorbed dose in air. At the same time, in a vacuum, the absorbed dose is zero. The equivalent dose, which characterizes the biological effect of irradiating the human body with ionizing radiation, is measured in sieverts. To understand the difference between dose and dose rate, we can draw an analogy with a kettle filled with tap water. The volume of water in the kettle is the dose, and the filling rate, which depends on the thickness of the water jet, is the dose rate, that is, the increment in the radiation dose per unit time. The dose equivalent rate is measured in sieverts per unit time, such as microsieverts per hour or millisieverts per year. Radiation is mostly invisible to the naked eye, so special measuring devices are used to determine the presence of radiation. One of the widely used devices is a dosimeter based on a Geiger-Muller counter. The counter consists of a tube in which the number of radioactive particles is counted, and a display that displays the number of these particles in different units, most often as the amount of radiation over a certain period of time, for example, per hour. Instruments with Geiger counters often emit short beeps, such as clicks, each of which means that a new emitted particle or several particles has been counted. This sound can usually be turned off. Some dosimeters allow you to select the click rate. For example, you can set the dosimeter to beep only after every twentieth particle counted, or less frequently. In addition to Geiger counters, dosimeters also use other sensors, such as scintillation counters, which make it possible to better determine which type of radiation currently prevails in the environment. Scintillation counters are good at detecting both alpha and beta and gamma radiation. These counters convert the energy released during radiation into light, which is then converted in a photomultiplier into an electrical signal, which is measured. During measurements, these counters work with a larger surface than Geiger counters, so the measurements are more efficient. Ionizing radiation has a very high energy, and therefore it ionizes the atoms and molecules of biological material. As a result, electrons are separated from them, 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. Such violations are often found in the normal functioning of cells, while 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 normal 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 excessive cell division in patients' bodies - which in turn increases the chance of cancer. Today, our knowledge about the effect of radiation on the body and about the conditions under which this effect is aggravated is limited, since researchers have very little material at their disposal. Much of our knowledge is based on case histories of victims of the atomic bombings of Hiroshima and Nagasaki, as well as victims of the Chernobyl explosion. It is also 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 Soviet nuclear test site on Novaya Zemlya, 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. 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. Thank you for your attention! If you liked this video, please don't forget to subscribe to our channel!

The name comes from the name of Wilhelm Roentgen, who discovered a new type of radiation in 1895. In 1895, W. Grubbe, while working with X-rays, received a radioactive burn of his hands, in 1896, A. Becquerel, while working with radium, received a severe skin burn. The term "radioactivity" was proposed by Marie Curie. In 1898, she and her husband Pierre Curie noted that after radiation, uranium turns into polonium and radium. Science has proposed many areas of application of X-rays: the military, medicine, energy, biology. The creation of nuclear charges based on a chain reaction, the bombing of Hiroshima and Nagasaki, active testing of nuclear weapons in the atmosphere made it necessary to study the effect of radioactive substances on the biosphere more closely. Since 1954, nuclear power plants have been launched in the USSR and in 1956 in Great Britain. Industrial accidents, the Chernobyl disaster in 1986, technical errors in research and, often, elementary illiteracy lead to a constant increase in the number of victims of ionizing radiation in peacetime. The severity of the negative effects of radiation on the body directly depends on the distance from the lesion, the duration of exposure, the type and power of radiation, environmental conditions, the presence of protective structures and terrain features. The amount of energy transferred to the body is called the dose.

Radiation dose - roentgen (r). A radiation dose of 1 r corresponds to the formation of approximately 2 billion pairs of ions in one cubic centimeter of air.

The absorbed dose is the amount of ionizing radiation energy absorbed by a unit mass of an irradiated organism. It is measured in the SI system in grays (Gy). The off-system unit of absorbed dose is rad (1 rad = 0.01 Gy). Alpha radiation is 20 times more dangerous than beta or gamma radiation at the same absorbed dose. In this regard, an equivalent dose has been proposed.

The equivalent dose is calculated taking into account the intensity of the damaging factor of different types of radiation - it is multiplied by the corresponding coefficient. It is measured in the SI system in units called sieverts (Sv). Non-system units of equivalent dose - rem (1 rem=0.01 Sv).

Effective equivalent dose - takes into account the different sensitivity of tissues and organs to ionizing radiation. The equivalent dose is multiplied by the corresponding coefficients for each type of organs and tissues, summed up. (The body as a whole - 1.0 Red bone marrow - 0.12 Ovaries and testes - 0.25 Mammary gland - 0.15 Lungs - 0.12 Thyroid gland - 0.03 Bone tissue - 0.03 Other organs - 0.3) . Measured in sieverts.

Collective effective equivalent dose - the individual effective equivalent doses received by a group of people are summed up.

Types of radiation:

l Alpha particles (helium nuclei) - penetrate superficially up to 0.07 mm, high ionization, dangerous when incorporated

l Beta particles (electrons and positrons) - penetrate up to 1 mm., less ionizing

l Gamma rays (photons, quanta) - penetrate to the full depth, are able to form secondary ionizing particles

l Neutrons are the most powerful and penetrating radiation

l Conducted radiation, residual radiation

Induced radioactivity is due to radioactive isotopes formed in the soil as a result of its irradiation with neutrons emitted at the time of the explosion by the nuclei of atoms of chemical elements that make up the soil. The resulting isotopes, as a rule, are beta-active, the decay of many of them is accompanied by gamma radiation. Induced activity can be dangerous only in the first hours after the explosion.

This article is devoted to the topic of absorbed radiation dose (i-tion), ionizing radiation and their types. It contains information about diversity, nature, sources, calculation methods, units of absorbed radiation dose and much more.

The concept of absorbed radiation dose

Radiation dose is a value used by such sciences as physics and radiobiology in order to assess the degree of impact of ionizing radiation on the tissues of living organisms, their life processes, and also on substances. What is called the absorbed dose of radiation, what is its value, the form of exposure and the variety of forms? It is mainly presented in the form of interaction between the medium and ionizing radiation, and is called the ionization effect.

The absorbed dose has its own methods and units of measurement, and the complexity and variety of the processes occurring under the influence of radiation give rise to some species diversity in the forms of the absorbed dose.

Ionizing form of radiation

Ionizing radiation is a stream of various types of elementary particles, photons or fragments formed as a result of atomic fission and capable of causing ionization in a substance. Ultraviolet radiation, like the visible form of light, does not belong to this type of radiation, nor do they include infrared radiation and emitted by radio bands, which is due to their small amount of energy, which is not enough to create atomic and molecular ionization in the ground state.

Ionizing type of radiation, its nature and sources

The absorbed dose of ionizing radiation can be measured in various SI units and depends on the nature of the radiation. The most significant types of radiation are: gamma radiation, beta particles of positrons and electrons, neutrons, ions (including alpha particles), x-rays, short-wave electromagnetic (high-energy photons) and muons.

The nature of sources of ionizing radiation can be very diverse, for example: spontaneously occurring radionuclide decay, thermonuclear reactions, rays from space, artificially created radionuclides, nuclear-type reactors, an elementary particle accelerator and even an X-ray apparatus.

How does ionizing radiation work?

Depending on the mechanism by which the substance and ionizing radiation interact, it is possible to single out a direct flow of particles of a charged type and radiation that acts indirectly, in other words, a photon or proton flow, a flow of neutral particles. The formation device allows you to select the primary and secondary forms of ionizing radiation. The absorbed radiation dose rate is determined in accordance with the type of radiation to which the substance is exposed, for example, the effect of the effective dose of rays from space on the earth's surface, outside the shelter, is 0.036 μSv / h. It should also be understood that the type of radiation dose measurement and its indicator depend on the sum of a number of factors, speaking of cosmic rays, it also depends on the latitude of the geomagnetic species and the position of the eleven-year cycle of solar activity.

The energy range of ionizing particles is in the range of indicators from a couple of hundred electron volts and reaches values ​​of 10 15-20 electron volts. The length of the run and the ability to penetrate can vary greatly, ranging from a few micrometers to thousands or more kilometers.

Introduction to exposure dose

The ionization effect is considered to be the main characteristic of the form of interaction between radiation and the medium. In the initial period of the formation of radiation dosimetry, radiation was mainly studied, the electromagnetic waves of which lay within the limits between ultraviolet and gamma radiation, due to the fact that it is widespread in the air. Therefore, the level of air ionization served as a quantitative measure of radiation for the field. Such a measure became the basis for creating an exposure dose determined by the ionization of air under conditions of normal atmospheric pressure, while the air itself must be dry.

The exposure absorbed dose of radiation serves as a means of determining the ionizing possibilities of radiation of X-rays and gamma rays, shows the radiated energy, which, having undergone transformation, has become the kinetic energy of charged particles in a fraction of the air mass of the atmosphere.

The unit of absorbed radiation dose for the exposure type is the coulomb, the SI component, divided by kg (C/kg). Type of non-systemic unit of measurement - roentgen (P). One pendant/kg corresponds to 3876 roentgens.

Absorbed amount

The absorbed radiation dose, as a clear definition, has become necessary for a person due to the variety of possible forms of exposure of one or another radiation to the tissues of living beings and even inanimate structures. Expanding, the known range of ionizing types of radiation showed that the degree of influence and impact can be very diverse and is not subject to the usual definition. Only a specific amount of absorbed radiation energy of the ionizing type can give rise to chemical and physical changes in tissues and substances exposed to radiation. The very number needed to trigger such changes depends on the type of radiation. The absorbed dose of i-nia arose precisely for this reason. In fact, this is an energy quantity that has undergone absorption by a unit of matter and corresponds to the ratio of the ionizing type energy that was absorbed and the mass of the subject or object that absorbs radiation.

The absorbed dose is measured using the unit gray (Gy) - an integral part of the C system. One gray is the amount of dose capable of transmitting one joule of ionizing radiation to 1 kilogram of mass. Rad is a non-systemic unit of measurement, in terms of value 1 Gy corresponds to 100 rad.

Absorbed dose in biology

Artificial irradiation of tissues of animal and plant origin clearly demonstrated that different types of radiation, being in the same absorbed dose, can affect the body and all biological and chemical processes occurring in it in different ways. This is due to the difference in the number of ions created by lighter and heavier particles. For the same path along the tissue, a proton can create more ions than an electron. The denser the particles are collected as a result of ionization, the stronger will be the destructive effect of radiation on the body, under conditions of the same absorbed dose. It is in accordance with this phenomenon, the difference in the strength of the effects of different types of radiation on tissues, that the designation of the equivalent dose of radiation was put into use. Absorbed Radiation is the amount of radiation received by the body, calculated by multiplying the absorbed dose and a specific factor called the Relative Biological Efficiency Ratio (RBE). But it is also often referred to as the quality factor.

The units of absorbed dose of the equivalent type of radiation are measured in SI, namely sieverts (Sv). One Sv is equal to the corresponding dose of any radiation that is absorbed by one kilogram of tissue of biological origin and causes an effect equal to the effect of 1 Gy of photon-type radiation. Rem - is used as an off-system measuring indicator of the biological (equivalent) absorbed dose. 1 Sv corresponds to one hundred rems.

Effective Dose Form

The effective dose is an indicator of magnitude, which is used as a measure of the risk of long-term effects of human exposure, its individual parts of the body, from tissues to organs. This takes into account its individual radiosensitivity. The absorbed dose of radiation is equal to the product of the biological dose in parts of the body by a certain weighting factor.

Different human tissues and organs have different radiation susceptibility. Some organs may be more likely than others to develop cancer at the same absorbed dose equivalent value, for example, the thyroid is less likely to develop cancer than the lungs. Therefore, a person uses the created radiation risk coefficient. CRC is a means for determining the dose of i-tion affecting organs or tissues. The total indicator of the degree of influence on the body of an effective dose is calculated by multiplying the number corresponding to the biological dose by the CRC of a particular organ, tissue.

The concept of collective dose

There is a concept of group absorption dose, which is the sum of the individual set of effective dose values ​​in a particular group of subjects over a certain time period. Calculations can be made for any settlements, up to states or entire continents. To do this, multiply the average effective dose and the total number of subjects exposed to radiation. This absorbed dose is measured using the man-sievert (man-Sv.).

In addition to the above forms of absorbed doses, there are also: commitment, threshold, collective, preventable, maximum allowable, biological dose of gamma-neutron type radiation, lethal-minimum.

The strength of the dose and units of measurement

The indicator of the intensity of exposure is the substitution of a specific dose under the influence of a certain radiation for a temporary measuring unit. This value is characterized by the difference in the dose (equivalent, absorbed, etc.) divided by the unit of time. There are many custom built units.

The absorbed dose of radiation is determined by a formula suitable for a particular radiation and the type of absorbed amount of radiation (biological, absorbed, exposure, etc.). There are many ways to calculate them, based on different mathematical principles, and different units of measurement are used. Examples of units of measurement are:

1. Integral view - gray kilogram in SI, outside the system is measured in rad grams.
2. The equivalent form is sievert in SI, outside the system it is measured in rem.
3. Exposure type - pendant-kilogram in SI, outside the system is measured - in roentgens.

There are other units of measurement corresponding to other forms of absorbed radiation dose.

findings

Analyzing these articles, we can conclude that there are many types, both of the ionizing radiation itself, and the forms of its effect on substances of animate and inanimate nature. All of them are measured, as a rule, in the SI system of units, and each type corresponds to a certain system and non-system measuring unit. Their source can be the most diverse, both natural and artificial, and the radiation itself plays an important biological role.

Questions.

1. What is the reason for the negative effects of radiation on living beings?

Ionizing radiation passing through living tissue knocks out electrons from molecules and atoms, destroys it, which negatively affects human health.

2. What is called the absorbed dose of radiation? By what formula is it determined and in what units is it measured?

3. Does radiation cause more harm to the body at a higher or lower dose if all other conditions are the same?

With a higher dose of radiation, the harm is greater.

4. Do different types of ionizing radiation cause the same or different biological effect in a living organism? Give examples.

Different types of ionizing radiation have a different biological effect. For α-radiation it is 20 times greater than for γ-radiation.

5. What does the radiation quality factor show? What is it equal to for α-, β-, γ- and X-ray radiation?

The quality factor K shows how many times the radiation hazard from exposure to a living organism of this type of radiation is greater than from exposure to γ-radiation. For the same absorbed dose of β-, γ and X-ray radiation, it is taken equal to 1, and for α-radiation it is equal to 20.

6. In connection with what and for what was the quantity called the equivalent radiation dose introduced? By what formula is it determined and in what units is it measured?

The radiation equivalent dose H was introduced to assess the measure of exposure to different types of radiation. It is calculated by the formula H \u003d D * K, where H is the equivalent radiation dose, D is the absorbed radiation dose, K is the quality factor, and in the SI system its unit is the sievert (Sv).

7. What other factor (besides energy, type of radiation and body mass) should be taken into account when assessing the effects of ionizing radiation on a living organism?

When assessing the impact of ionizing radiation on a living organism, one should also take into account the time of its exposure, because radiation doses accumulate, as well as the different sensitivity of body parts to this radiation, taken into account using the radiation risk coefficient.

8. What percentage of the atoms of a radioactive substance will remain after 6 days if its half-life is 2 days?

9. Tell us about the ways to protect against the effects of radioactive particles and radiation.

To protect against radioactivity, contact with such substances should be avoided, in no case should they be taken into hands, beware of ingestion. In all cases, radioactive radiation, depending on its nature, has a different penetrating ability, for some types of radiation it is enough to avoid direct contact (α-radiation), protection from others can be a distance or thin layers of an absorber (walls of houses, a metal case of a car) or thick layers of concrete or lead (hard γ-radiation).

The main characteristic of the interaction of ionizing radiation and the medium is the ionization effect. In the initial period of the development of radiation dosimetry, it was most often necessary to deal with X-rays propagating in the air. Therefore, the degree of air ionization of X-ray tubes or apparatuses was used as a quantitative measure of the radiation field. A quantitative measure based on the amount of ionization of dry air at normal atmospheric pressure, which is fairly easy to measure, is called exposure dose.

The exposure dose determines the ionizing ability of X-rays and gamma rays and expresses the radiation energy converted into the kinetic energy of charged particles per unit mass of atmospheric air. The exposure dose is the ratio of the total charge of all ions of the same sign in an elementary volume of air to the mass of air in this volume.

In the SI system, the unit of exposure dose is the coulomb divided by the kilogram (C/kg). Off-system unit - x-ray (R). 1 C/kg = 3880 R

Absorbed dose

With the expansion of the range of known types of ionizing radiation and the scope of its application, it turned out that the measure of the effect of ionizing radiation on a substance cannot be easily determined due to the complexity and diversity of the processes occurring in this case. An important of them, giving rise to physicochemical changes in the irradiated substance and leading to a certain radiation effect, is the absorption of the energy of ionizing radiation by the substance. As a result, the concept absorbed dose. The absorbed dose shows how much radiation energy is absorbed per unit mass of any irradiated substance and is determined by the ratio of the absorbed ionizing radiation energy to the mass of the substance.

In SI units, absorbed dose is measured in joules per kilogram (J/kg) and has a special name - Gray (Gr). 1 Gr is the dose at which the mass 1 kg ionizing radiation energy is transferred 1 J. The off-system unit of absorbed dose is glad.1 Gy=100 rad.

The absorbed dose is a fundamental dosimetric value, it does not reflect the biological effect of irradiation.

Dose equivalent

Dose equivalent (E,HT,R) reflects the biological effect of irradiation. The study of individual effects of irradiation of living tissues has shown that with the same absorbed doses, different types of radiation produce unequal biological effects on the body. This is due to the fact that a heavier particle (for example, a proton) produces more ions per unit path in the tissue than a light one (for example, an electron). With the same absorbed dose, the radiobiological destructive effect is the higher, the denser the ionization created by the radiation. To take this effect into account, the notion equivalent dose. The equivalent dose is calculated by multiplying the value of the absorbed dose by a special coefficient - the coefficient of relative biological effectiveness ( OBE) or the quality factor of a given type of radiation ( WR), reflecting its ability to damage body tissues.

When exposed to different types of radiation with different quality factors, the equivalent dose is defined as the sum of the equivalent doses for these types of radiation.

The SI unit of equivalent dose is sievert (Sv) and is measured in joules per kilogram ( j/kg). Value 1 Sv equal to the equivalent dose of any type of radiation absorbed in 1 kg biological tissue and creating the same biological effect as the absorbed dose in 1 Gr photon radiation. The off-system unit of equivalent dose is Baer(until 1963 - biological equivalent x-ray, after 1963 - biological equivalent glad). 1 Sv = 100 rem.

Quality factor - in radiobiology, the average coefficient of relative biological effectiveness (RBE). Characterizes the danger of this type of radiation (compared to γ-radiation). The higher the coefficient, the more dangerous this radiation. (The term should be understood as "harm quality factor").

The values ​​of the quality factor of ionizing radiation are determined taking into account the impact of the microdistribution of absorbed energy on the adverse biological consequences of chronic human exposure to low doses of ionizing radiation. For the quality factor, there is GOST 8.496-83. GOST as a standard is used to control the degree of radiation hazard for persons exposed to ionizing radiation during work. The standard is not applicable for acute exposures and during radiotherapy.

The RBE of a particular type of radiation is the ratio of the absorbed dose of X-ray (or gamma) radiation to the absorbed dose of radiation at the same equivalent dose.

Quality factors for types of radiation:
Photons (γ-radiation and X-rays), by definition	1
β radiation (electrons, positrons)	1
Muons	1
α-radiation with energy less than 10 MeV	20
Neutrons (thermal, slow, resonance), up to 10 keV	5
Neutrons from 10 keV to 100 keV	10
Neutrons from 100 keV to 2 MeV	20
Neutrons from 2 MeV to 20 MeV	10
Neutrons over 2 MeV	5
Protons, 2…5 MeV	5
Protons, 5…10 MeV	10
Heavy recoil nuclei	20

Effective dose

Effective dose, (E, effective equivalent dose) is a value used in radiation protection as a measure of the risk of long-term effects of exposure ( stochastic effects) of the whole human body and its individual organs and tissues, taking into account their radiosensitivity.

Different parts of the body (organs, tissues) have different sensitivity to radiation exposure: for example, with the same dose of radiation, the occurrence of cancer in the lungs is more likely than in the thyroid gland. The effective equivalent dose is calculated as the sum of equivalent doses to all organs and tissues, multiplied by the weighting factors for these organs, and reflects the total effect of exposure to the body.

Weighted coefficients are established empirically and calculated in such a way that their sum for the whole organism is one. Units effective dose match the units of measurement equivalent dose. It is also measured in Sievertach or Baerach.

Fixed effective equivalent dose (CEDE - the committed effective dose equivalent) is an estimate of the doses of radiation per person, as a result of inhalation or consumption of a certain amount of a radioactive substance. CEDE is expressed in rems or sieverts (Sv) and takes into account the radiosensitivity of various organs and the time during which the substance remains in the body (up to a lifetime). Depending on the situation, CEDE may also refer to radiation dose to a specific organ rather than to the whole body.

Effective and equivalent doses- these are normalized values, i.e. values ​​that are a measure of damage (harm) from the effects of ionizing radiation on a person and his descendants. Unfortunately, they cannot be directly measured. Therefore, operational dosimetric veins are introduced into practice, which are uniquely determined through the physical characteristics of the radiation field at a point, as close as possible to the normalized ones. The main operating value is ambient dose equivalent(synonyms - ambient dose equivalent, ambient dose).

Ambient dose equivalent H*(d) is the dose equivalent that was created in the spherical phantom ICRU(International Commission on Radiation Units) at a depth d (mm) from the surface along a diameter parallel to the direction of radiation, in a radiation field identical to that considered in composition, fluence and energy distribution, but unidirectional and homogeneous, i.e. The ambient dose equivalent H*(d) is the dose that a person would receive if they were at the location where the measurement is being taken. Unit of ambient dose equivalent — Sievert (Sv).

Group doses

By calculating the individual effective doses received by individuals, one can arrive at a collective dose - the sum of individual effective doses in a given group of people over a given period of time. The collective dose can be calculated for the population of a particular village, city, administrative-territorial unit, state, etc. It is obtained by multiplying the average effective dose by the total number of people who were exposed to radiation. The unit of measure for the collective dose is man-sievert (man-sound), off-system unit - man-rem (man-rem).

In addition, the following doses are distinguished:

• commitment- the expected dose, half a century dose. It is used in radiation protection and hygiene when calculating absorbed, equivalent and effective doses from incorporated radionuclides; has the dimension of the corresponding dose.
• collective- a calculated value introduced to characterize the effects or damage to health from exposure of a group of people; unit - Sievert (Sv). The collective dose is defined as the sum of the products of average doses and the number of people in dose intervals. The collective dose can accumulate for a long time, not even one generation, but covering subsequent generations.
• threshold- the dose below which no manifestations of this irradiation effect are noted.
• maximum allowable doses (SDA)- the highest values ​​of the individual equivalent dose per calendar year, at which uniform exposure for 50 years cannot cause adverse changes in the state of health detected by modern methods (NRB-99)
• preventable is the predicted dose due to a radiation accident that can be prevented by protective measures.
• doubling- a dose that doubles (or 100%) the rate of spontaneous mutations. The doubling dose is inversely proportional to the relative mutational risk. According to currently available data, the doubling dose for acute exposure is on average 2 Sv, and for chronic exposure is about 4 Sv.
• biological dose of gamma-neutron radiation- the dose of gamma irradiation equally effective in terms of damage to the body, taken as standard. Equal to the physical dose of the given radiation, multiplied by the quality factor.
• minimally lethal- the minimum dose of radiation that causes the death of all irradiated objects.

Dose rate

Dose rate (radiation intensity) is the increment of the corresponding dose under the influence of this radiation per unit of time. It has the dimension of the corresponding dose (absorbed, exposure, etc.) divided by a unit of time. Various special units are allowed (for example, microroentgen/hour, Sv/h, rem/min, cSv/year and etc.).