The damage caused in a living organism by radiation will be the greater, the more radiation energy is transferred to the tissues. The amount of such energy transferred to the body is called dose. The measured physical quantities associated with the radiation effect are called dosimetric quantities. The task of dosimetry is to measure certain physical quantities for predicting or assessing the radiation effect, in particular radiobiological. Common dosimetric quantities are absorbed dose, exposure dose, equivalent dose, effective equivalent dose, expected dose, and collective dose. How can these doses be determined? If a person is exposed to ionizing radiation, then it is necessary to know the distribution of radiation intensity in space. In addition, the absorbency of tissues is different. Therefore, the exposure dose is used to characterize the energy of ionizing radiation.

Exposure dose - a measure of the ionization effect of photon radiation, determined by the ionization of air under conditions of electronic equilibrium, i.e. if the absorbed radiation energy in a certain volume of the medium is equal to the total kinetic energy of ionizing particles (electrons, protons).

The exposure dose is a directly measurable physical quantity.

The SI unit of exposure dose is one Coulomb per kilogram (C / kg). The non-systemic unit of the exposure dose is roentgen. , a.

X-ray - a unit of exposure dose of X-ray and gamma radiation, during the passage of which through the air, as a result of the completion of all ionization processes caused by this radiation, a pair of ions is formed. Note that is the mass of dry atmospheric air under normal conditions. The exposure dose characterizes the radiation environment regardless of the properties of the irradiated objects.

The absorption capacity of an object can vary greatly depending on the radiation energy, its type and intensity, as well as on the properties of the absorbing object itself. To characterize the absorbed energy of ionizing radiation, it is clear that absorbed dose defined as the absorption energy and unit mass of the irradiated substance. The unit of absorbed dose is expressed in grey (Gr),. The unit is named for Louis Harold Gray, a Roentgen Prize-winning radiobiologist. The non-systemic unit of the absorbed dose is glad : - ; .

The term is often used integral dose , those. energy, total absorbed in the entire volume of the object. The integral dose is measured in Joules ().

The absorbed dose does not take into account the spatial distribution of the absorbed energy. At the same absorbed dose, alpha radiation is much more dangerous than beta or gamma radiation. To take this phenomenon into account, the concept of an equivalent dose is introduced.

Equivalent dose radiation is the absorbed dose multiplied by the coefficient reflecting the ability of this type of radiation to damage the tissues of the body; alpha radiation is considered 20 times more dangerous than other types of radiation. In SI for a unit of equivalent radiation dose, use is sievert (Sound). This unit is named for Sievert, a prominent researcher in the field of dosimetry and radiation safety. On his initiative, a network of stations for monitoring radioactive contamination of the external environment was created. The off-system unit of the equivalent radiation dose is rem .

The equivalent radiation dose can be found through the absorbed dose multiplied by the average radiation quality factor of the biological tissue of the standard composition and by the modifying factor :

If the radiation is mixed, then the formula will have the form

where - index of the type of radiation energy.

The radiation quality factor used in the formulas is a dimensionless factor, which is intended to take into account the influence of the microdistribution of absorbed energy on the degree of manifestation of a harmful biological effect. The values ​​of the quality factor for different types of radiation are given in Table 1.

Table 1

Quality factor for different types of radiation

It should also be borne in mind that some parts of the body (organs, tissues) are more sensitive than others. For example, given the same equivalent dose of radiation, lung cancer is more likely than thyroid cancer. Therefore, the radiation doses to organs and tissues should also be taken into account with different coefficients.

The radiation risk coefficients for different tissues (organs) of a person with uniform irradiation of the whole body, recommended for calculating the effective equivalent dose, are given in Table 2.

table 2

Radiation risk ratios

Multiplying the equivalent dose by the corresponding coefficients and summing over all organs and tissues, we obtain efficiently -equivalent dose , reflecting the total effect of radiation on the body. It is also measured in sieverts.

The considered concepts describe only the individually received doses. Summing up the individual equivalent doses received by a group of people, we come to collective effective dose , which is measured in man-sieverts (people - Sv).

In addition, another definition is being introduced, since many radionuclides decay very slowly and will remain radioactive in a certain future. The collective effective equivalent dose that many generations of people receive is called the expected (full) collective effective equivalent dose.

Dose rate

Radiation dose rate- a value equal to the ratio of the radiation dose to the exposure time. Distinguish:

• 1) absorbed dose rate(unit - gray per second (Gy / s));
• 2) exposure dose rate(unit is ampere per kilogram (A / kg)).

The human body absorbs the energy of ionizing radiation, and the degree of radiation damage depends on the amount of absorbed energy. To characterize the absorbed energy of ionizing radiation by a unit mass of a substance, the concept of absorbed dose is used.

Absorbed dose Is the amount of ionizing radiation energy absorbed by the irradiated body (body tissues) and calculated per unit mass of this substance. The unit of absorbed dose in the International System of Units (SI) is gray (Gy).

1 Gy = 1 J / kg

For the assessment, they also use a non-systemic unit - Rad. Rad - derived from the English "radiationabsorbeddoze" - absorbed dose of radiation. This is such radiation in which each kilogram of mass of a substance (say, a human body) absorbs 0.01 J of energy (or 1 g of mass absorbs 100 erg).

1 Rad = 0.01 J / kg 1 Gr = 100 Rad

Exposure dose

To assess the radiation situation on the ground, in the work or living quarters, caused by exposure to X-ray or gamma radiation, use exposure dose irradiation. In the SI system, the unit of exposure dose is a pendant per kilogram (1 C / kg).

In practice, an off-system unit is more often used - x-ray (R). 1 X-ray is the dose of X-rays (or gamma) rays, at which 2.08 x 10 9 pairs of ions are formed in 1 cm 3 of air (or 1.61 x 10 12 pairs of ions in 1 g of air).

1 P = 2.58 x 10 -3 C / kg

The absorbed dose of 1 Rad corresponds to an exposure dose approximately equal to 1 X-ray: 1 Rad = 1 R

Equivalent dose

When living organisms are irradiated, various biological effects arise, the difference between which at the same absorbed dose is explained by different types of irradiation.

To compare the biological effects caused by any ionizing radiation with the effects of X-ray and gamma radiation, the concept of equivalent dose... In the SI system, the unit of the equivalent dose is the sievert (Sv). 1 Sv = 1 J / kg

There is also a non-systemic unit of the equivalent dose of ionizing radiation - rem (biological equivalent of an X-ray). 1 rem is a dose of any radiation that produces the same biological effect as X-ray or gamma radiation in 1 X-ray.

1 rem = 1 R 1 Sv = 100 rem

The coefficient showing how many times the evaluated type of radiation is biologically more dangerous than X-ray or gamma radiation at the same absorbed dose is called radiation quality factor (K).

For X-ray and gamma radiation, K = 1.

1 Rad x K = 1 rem 1 Gr x K = 1 Sv

All other things being equal, the dose of ionizing radiation is the greater, the longer the exposure time, i.e. the dose builds up over time. The dose per unit of time is called dose rate. If we say that the exposure dose rate of gamma radiation is 1 R / h, then this means that for 1 hour of irradiation a person will receive a dose equal to 1 R.

Activity of a radioactive source (radionuclide) is a physical quantity that characterizes the number of radioactive decays per unit of time. The more radioactive transformations occur per unit of time, the higher the activity. In the C system, becquerel (Bq) is taken as a unit of activity - the amount of radioactive substance in which 1 decay occurs in 1 second.

Another unit of radioactivity is curie. 1 curie is the activity of such an amount of radioactive substance in which 3.7 x 10 10 decays per second occur.

The time during which the number of atoms of a given radioactive substance decreases due to decay by half is called half-life ... The half-life can vary widely: for uranium-238 (U) - 4.47 billion. years; uranium-234 - 245 thousand years; radium-226 (Ra) - 1600 years; iodine-131 (J) - 8 days; radon-222 (Rn) - 3.823 days; polonium-214 (Po) - 0.000164 sec.

Among the long-lived isotopes released into the atmosphere as a result of the explosion of the nuclear power plant in Chernobyl, there are strontium-90 and cesium-137, whose half-lives are about 30 years, therefore the Chernobyl nuclear power plant zone will be unsuitable for normal life for many decades.

RADIATION RISK RATES

It should be borne in mind that some parts of the body (organs, tissues) are more sensitive than others: for example, at the same equivalent dose of radiation, the occurrence of cancer in the lungs is more likely than in the thyroid gland, and irradiation of the gonads is especially dangerous because of the risk of genetic damage. Therefore, the radiation doses to organs and tissues should be taken into account with different coefficients. Taking the radiation risk coefficient of the whole organism as a unit, for different tissues and organs the radiation risk coefficients will be as follows:

0.03 - bone tissue; 0.03 - thyroid gland;

0.12 - lungs; 0.12 - red bone marrow;

0.15 - mammary gland; 0.25 - ovaries or testes;

0.30 - other fabrics.

HUMAN RADIATION DOSES

Population in any region of the world encounters ionizing radiation every day. This is, first of all, the so-called radiation background of the Earth, which consists of:

cosmic radiation coming to Earth from Space;

radiation from natural radioactive elements in soil, building materials, air and water;

radiation from natural radioactive substances that enter the body with food and water, are fixed by tissues and stored in the human body.

In addition, a person encounters artificial sources of radiation, including radioactive nuclides (radionuclides), created by human hands and used in the national economy.

On average, the dose of radiation from all natural sources of ionizing radiation is about 200 mR per year, although this value can vary in different regions of the world from 50 to 1000 mR / year or more (Table 1). The dose received from cosmic radiation depends on the height above sea level; the higher above sea level, the greater the annual dose.

Table 1

Natural sources of ionizing radiation

Artificial sources of ionizing radiation (Table 2):

medical diagnostic and treatment equipment;

people who constantly use the plane are additionally exposed to minor radiation;

nuclear and thermal power plants (the dose depends on the proximity of their location);

phosphate fertilizers;

Buildings made of stone, brick, concrete, wood - poor ventilation in rooms can increase the radiation dose due to inhalation of radioactive radon gas, which is formed during the natural decay of radium contained in many rocks and building materials, as well as in soil. Radon is an invisible, tasteless and odorless heavy gas (7.5 times heavier than air), etc.

Every inhabitant of the Earth throughout his life is annually irradiated with an average dose of 250-400 mrem.

It is believed that it is safe for a person to gain a dose of radiation that does not exceed 35 rem in his entire life. At radiation doses of 10 rem, no changes are observed in the organs and tissues of the human body. With a single irradiation with a dose of 25-75 rem, short-term insignificant changes in blood composition are clinically determined.

With irradiation with a dose of more than 100 rem, the development of radiation sickness is observed:

100 - 200 rem - I degree (light);

200 - 400 rem - degree II (average);

400 - 600 rem - III degree (heavy);

more than 600 rem - IV degree (extremely heavy).

The impact of radiation on living organisms is characterized by dose of radiation.

Exposure dose X of ionizing radiation - the total charge formed due to radiation in 1 cm 3 of air for some time t.

Measured in pendants on kilogram (Cl / kg), off-system unit - x-ray (R).

At a dose of 1 R in 1 cm 3 under normal conditions, 2.08 is formed. 10 9 pairs of ions, which corresponds to 2.58. 10 -4 Cl / kg... Moreover, in 1 cm 3 air due to ionization absorbed energy equal to 1.1. 10 -8 J, i.e. 8.5 mJ / kg.

The absorbed dose of radiation D p. Is a physical quantity equal to the ratio of the absorbed energy W p to the mass M p of the irradiated substance. The values ​​of the absorbed dose are determined using the expression

D p = W p / M p.

In the SI system, the unit of absorbed dose is Gray. This unit is named after the English physicist A. Gray. This dose is received by a body weighing 1 kg if it absorbed energy in 1 J.

Until 1980, the following units of absorbed dose were used: rad and x-ray. These are non-systemic units.

Glad - from the English. absorbed dose of radiation.

1 glad= 10 -2 J / kg = 10 -2 Gr.

1 Gray (Gy) = 100 rad »110 R (for gamma radiation).

The unit "X-ray" is still used quite often now; perhaps this is just a tribute to tradition. By definition, a dose of 1 R corresponds to such radiation at which in 1 cm 3 air at n.u. ( P 0=760 mm. rt. st, T = 273 TO) a certain number of ion pairs (N »2.1 · 10 9) is formed, so that their total charge is 3.3 · 10 -10 Cl... The meaning of this definition is clear: knowing the current and discharge time, it is possible to experimentally determine the total ionization charge and the number of ion pairs resulting from irradiation

N ion = Q total / e.

For the same conditions (n.o.), we find the value of the absorbed dose:

D p = W p / M p= 112.5 · 10 -10 / 0.128 · 10 -5 = 8.7 · 10 -3 J / kg.

Thus, a dose of 1 X-ray corresponds to an absorbed dose of 8.7 · 10 -3 J / kg or 8.7 10 mGy.

1 Р = 8.7 · 10 -3 J / kg = 8.7 mGy.

A dose of 1 R is created by rays emitted by 1 gram of radium at a distance of 1 m from the source for 1 hour.

The absorbed dose rate D I P. is a physical quantity that characterizes the amount of energy absorbed by a unit of mass of any physical body per unit of time:

D 1 p = D P / t = W P / M Pp t.

The amount of background radiation is usually reported to us in microroentgen / hour, for example 15 μR / hour... This quantity has the dimension of the absorbed dose rate, but it is not expressed in SI units.

Equivalent dose H eq. Is a value that characterizes the absorbed dose of a living organism. It is equal to the absorbed dose multiplied by the coefficient reflecting the ability of this type of radiation to damage the tissues of the body:

H eq. = KK × D P,

where CC is the average coefficient of the quality of ionizing radiation in a given element of the volume of biological tissue (Table 22.1).

Table 22.1.e.

It should be noted that the equivalent dose H eq characterizes the average value of the absorbed dose by a living organism, although the same tissues (bones, muscles, brain, etc.) for different people and under different conditions will absorb different energy.

In the SI system, the unit of the equivalent dose is Sievert (1 Sv), named after the Swedish radiologist R. Sievert. In practice, a non-systemic unit of equivalent dose is often used - rem (biological equivalent of an X-ray).

1 rem= 0,01 J / kg.

In practice, fractional units are used: millirem (1 mrem = 10 -3 rem); microbar (1 mkrem= 10 -6 rem); nanoair (1 nber = 10 -9 rem).

There is another definition of the concept rem.

Rem is the amount of energy absorbed by a living organism when irradiated by any kind of ionizing radiation and causing the same biological effect as an absorbed dose of 1 rad of X-ray or g-radiation with an energy of 200 keV.

The ratio between the named units (1 Sv, 1 rem, 1 R) is:

1 Sv = 100 rem"110 R(for gamma radiation).

As you move away from a point source, the dose decreases in inverse proportion to the square of the distance (~ 1 / r 2).

Absorbed dose

D p = D 1 floor t region / r 2. [D 1 e m] = 1 R· 1m 2 / hour,

where D 1 et is the power of a point source; t obl - exposure time, h; r - distance from the source, m.

The activity of a point emitter and the dose rate are related by the ratio:

R = K g ,

where K g- ionization constant, r- distance from the radiation source, d- the thickness of the protective shield, - the absorption coefficient of radiation in the shield material.

Ionization constant K g and the absorption coefficient of the screen in a complex way depend on the type and energy of the radiation. For gamma quanta with an energy of about 1 MeV the ratio of the absorption coefficient to the density of the material for many materials (water, aluminum, iron, copper, lead, concrete, brick) is close to 7. 10 -3 m 2 / kg.

The natural background of radiation (cosmic rays; radioactivity of the environment and the human body) amounts to a radiation dose of about Gy per person per year. The International Commission on Radiation Protection has established a maximum permissible dose for the year of 0.05 Gy for persons working with radiation. A radiation dose of 3 - 10 Gy received in a short time is lethal.

When working with any source of radiation (radioactive isotopes, reactors, etc.), it is necessary to take measures for the radiation protection of all people who might get into the radiation zone.

The simplest method of protection is to remove personnel from the radiation source at a sufficiently large distance. Even without taking into account absorption in air, the radiation intensity decreases in proportion to the square of the distance from the source. Therefore, ampoules with radioactive drugs should not be taken by hand. It is necessary to use special long-handled forceps.

In cases where distance from the radiation source at a sufficiently large distance is impossible, obstacles made of absorbing materials are used to protect against radiation.

The most difficult protection against g-rays and neutrons due to their high penetrating power. The best g-ray absorber is lead. Slow neutrons are well absorbed by boron and cadmium. Fast neutrons are preliminarily slowed down with graphite.

Background at 15 μR / hour the dose rate corresponds to 36.2 · 10 –12 G / s(or 4.16 10 -9 R / s). With such a dose rate, a person in one year, provided that tissue ionization occurs in the same way as air ionization, will receive a radiation dose equal to 1.1 mGy(or 0.13 R). This dose of radiation is very small and harmless to humans. But we must also bear in mind that radiation can accumulate in building materials that are used in the construction of residential and industrial buildings. The influence of radiation from structural materials can be more significant than from the background of the outside air.

Knowing the total equivalent dose, it is possible to find the equivalent absorbed dose of individual organs ( H org, i = K pp × D eq) and assess the likelihood of their radiation damage. At the same time, when using radiation therapy in medicine, it is very important to know and set the values ​​of the power of the radiation source and the exposure time so that the equivalent absorbed dose for a given organ (for example, for the lungs) does not go beyond the admissible dose.

The action of ionizing radiation is a complex process. The effect of irradiation depends on the magnitude of the absorbed dose, its power, type of radiation, and the volume of irradiation of tissues and organs. For its quantitative assessment, special units have been introduced, which are divided into non-systemic and units in the SI system. Currently, SI units are used predominantly. Table 10 below gives a list of units of measurement of radiological quantities and a comparison of SI units and non-SI units.

Table 10.

The following concepts and units of measurement are used to describe the effect of ionizing radiation on a substance:
Radionuclide activity in the source (A)... The activity is equal to the ratio of the number of spontaneous nuclear transformations in this source over a short time interval (dN) to the value of this interval (dt):

The SI unit of activity is Becquerel (Bq).
Non-systemic unit - Curie (Ki).

The number of radioactive nuclei N (t) of a given isotope decreases with time according to the law:

N (t) = N 0 exp (-tln2 / T 1/2) = N 0 exp (-0.693t / T 1/2)

where N 0 is the number of radioactive nuclei at time t = 0, T 1/2 is the half-life - the time during which half of the radioactive nuclei decays.
The mass m of the radionuclide with activity A can be calculated by the formula:

m = 2.4 · 10 -24 × M × T 1/2 × A,

where M is the mass number of the radionuclide, A is the activity in Becquerels, T 1/2 is the half-life in seconds. The mass is obtained in grams.
Exposure dose (X). As a quantitative measure of X-ray and γ-radiation, it is customary to use the exposure dose in off-system units, which is determined by the charge of secondary particles (dQ) formed in the mass of the substance (dm) upon complete deceleration of all charged particles:

The unit of the exposure dose is Roentgen (R). X-ray is the exposure dose of X-ray and
- radiation, creating 1 cc of air at a temperature of O ° C and a pressure of 760 mm Hg. the total charge of ions of the same sign in one electrostatic unit of the amount of electricity. Exposure dose 1 R
corresponds to 2.08 · 10 9 pairs of ions (2.08 · 10 9 = 1 / (4.8 · 10 -10)). If we take the average energy of formation of 1 pair of ions in air equal to 33.85 eV, then at an exposure dose of 1 P, one cubic centimeter of air is transferred energy equal to:
(2.08 · 10 9) · 33.85 · (1.6 · 10 -12) = 0.113 erg,
and one gram of air:
0.113 / air = 0.113 / 0.001293 = 87.3 erg.
The absorption of the energy of ionizing radiation is the primary process that gives rise to a sequence of physicochemical transformations in the irradiated tissue, leading to the observed radiation effect. Therefore, it is natural to compare the observed effect with the amount of absorbed energy or absorbed dose.
Absorbed dose (D) is the main dosimetric quantity. It is equal to the ratio of the average energy dE transferred by ionizing radiation to a substance in an elementary volume to the mass dm of a substance in this volume:

The unit of the absorbed dose is Gray (Gy). The off-system unit Rad was defined as the absorbed dose of any ionizing radiation equal to 100 erg per 1 gram of the irradiated substance.
Equivalent dose (N)... To assess the possible damage to human health under conditions of chronic exposure in the field of radiation safety, the concept of an equivalent dose H was introduced, which is equal to the product of the absorbed dose D r created by irradiation - r and averaged over the analyzed organ or throughout the body by the weight factor wr (also called the coefficient radiation quality)
(table 11).

The unit of measure for equivalent dose is Joule per kilogram. It has the special name Sievert (Sv).

Table 11.

The effect of radiation is uneven. To assess the damage to human health due to the different nature of the effect of radiation on different organs (under conditions of uniform irradiation of the whole body), the concept of an effective equivalent dose E eff is introduced, which is used to assess possible stochastic effects - malignant neoplasms.
Effective dose is equal to the sum of the weighted equivalent doses in all organs and tissues:

where w t is a tissue weight factor (table 12), and H t is an equivalent dose absorbed in
fabrics - t. The unit of the effective equivalent dose is Sievert.

Table 12.

Collective effective equivalent dose. To assess the damage to the health of personnel and the population from stochastic effects caused by the action of ionizing radiation, the collective effective equivalent dose S is used, defined as:

where N (E) is the number of persons who received an individual effective equivalent dose E. The unit of S is a person-Sievert
(person-Sv).
Radionuclides- radioactive atoms with a given mass number and atomic number, and for isomeric atoms - and with a given specific energy state of the atomic nucleus. Radionuclides
(and non-radioactive nuclides) of an element is otherwise called its isotopes.
In addition to the above values, to compare the degree of radiation damage to a substance when it is exposed to various ionizing particles with different energies, the value of linear energy transfer (LET) is also used, determined by the ratio:

where is the average energy locally transferred to the medium by the ionizing particle due to collisions on the elementary path dl.
Threshold energy usually refers to the energy of an electron. If, in the collision event, the primary charged particle forms an -electron with an energy greater, then this energy is not included in the value of dE, and -electrons with energy are considered more as independent primary particles.
The choice of the threshold energy is arbitrary and depends on specific conditions.
It follows from the definition that the linear transfer of energy is a kind of analogue of the stopping power of a substance. However, there is a difference between these values. It consists in the following:
1. LET does not include energy converted to photons, i.e. radiation losses.
2. For a given threshold, the LET does not include the kinetic energy of particles exceeding.
The values ​​of the LET and the stopping power coincide if the losses due to bremsstrahlung and

Table 13.

By the value of the linear energy transfer, you can determine the weighting factor of this type of radiation (table 14)

Table 14.

Maximum permissible radiation doses

In relation to exposure, the population is divided into 3 categories.
Category A exposed persons or personnel (professional workers) - persons who permanently or temporarily work directly with sources of ionizing radiation.
Category B exposed persons or a limited part of the population - persons who do not work directly with sources of ionizing radiation, but due to living conditions or placement of workplaces may be exposed to ionizing radiation.
Category B exposed persons or population - the population of a country, republic, region or region.
For category A, maximum permissible doses are introduced - the highest values ​​of the individual equivalent dose for a calendar year, at which uniform irradiation over 50 years cannot cause adverse changes in the state of health that are detected by modern methods. For category B, a dose limit is determined.
Three groups of critical organs are established:
Group 1 - the whole body, gonads and red bone marrow.
Group 2 - muscles, thyroid gland, adipose tissue, liver, kidneys, spleen, gastrointestinal tract, lungs, eye lenses and other organs, with the exception of those belonging to groups 1 and 3.
Group 3 - skin, bone tissue, hands, forearms, legs and feet.
Dose limits of exposure for different categories of persons are given in Table 15.

Table 15.

In addition to the basic dose limits, derivative standards and reference levels are used to assess the effect of radiation. The standards are calculated taking into account the non-exceeding of the dose limits of the PDD (maximum permissible dose) and PD (dose limit). The calculation of the permissible content of a radionuclide in the body is carried out taking into account its radiotoxicity and non-exceeding of the SDA in the critical organ. The reference levels should provide such low levels of exposure as can be achieved by adhering to the basic dose limits.
For category A (personnel) the following are established:
- the maximum permissible annual intake of the RAP radionuclide through the respiratory system;
- permissible content of radionuclide in the critical organ of DS A;
- permissible dose rate of radiation DMD A;
- permissible particle flux density DPP A;
- permissible volumetric activity (concentration) of the radionuclide in the air of the working area of ​​DC A;
- permissible contamination of the skin, overalls and working surfaces of DZ A.
For category B (limited part of the population), the following are established:
- the limit of the annual intake of the GWP radionuclide through the respiratory or digestive organs;
- permissible volumetric activity (concentration) of radionuclide DK B in atmospheric air and water;
- permissible dose rate of DMD B;
- permissible particle flux density DPP B;
- permissible contamination of the skin, clothing and surfaces of DZ B.
The numerical values ​​of the permissible levels are contained in full in
"Standards of radiation safety".

Any substances, living organisms and their tissues.

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Hello everyone! Dmitry Pobedinsky is with you and I am glad to welcome you to the QWERTY Channel! comrades, let's remember school classes in Warsaw there was a lot of something in Prague separate explosions in the bar and bombs the shelter ended up letting go I don’t remember the details one year of them definitely radiation is dangerous and sometimes even fatal, but I wonder how exactly radiation beats just from the outside everything is clear the bullet is a fool or that they make a hole in their business, I start chemical reactions and communicators threaten them, but also the action of exactly how it affects a person, let's first remember what we already imagine to be reduced to a size 10 thousand times smaller than an atom then we can see then where do the main types of radiation come from the atomic nucleus, as we remember, it consists of protons and there are no mouths, and I know for some alimony it can be configured cop, roughly speaking, not quite the way it becomes unstable in them there is extra energy and in which they strive to get rid of and this can be done in several ways by throwing out a small piece of d va protons two neutrons are they to be cleaned in ugra a neutron can turn into a proton and vice versa, then this electron antirecord flies into this particle only with the opposite sign, and finally the nucleus can simply be thrown out if when the children, anticipating an electromagnetic wave, this one, like ultraviolet light, led this prime feet can also cleanse the bowels of the earth can emit neutrons protons broke into pieces besides, radiation particles can fly from space appears in accelerators and other devices, but despite the differences in the origin and restructuring of any types of radiation, the most important thing is that this particle flux is at the rate of and energy, the effect of radiation on a person who looks like a snowball, everything starts small, but then the consequences grow and grow until they lead to irreversible changes, several stations can be distinguished so the radiation particles of the face are faster than any path so quickly that they knock out electrons from the tents, the negative electrode, respectively, the act of receiving the loss becomes positive ions, that's all that radiation does, but the flow of free electrons and they are isolated, the atom almost immediately participates in complex reaction chains in which chemically active molecules can be formed, including the so-called free radicals well, for example, water of which a person consists of 80 percent of us under the influence of radiation breaks down into two radicals, as much as its free radicals actively react with important biological molecules dorenko beat Chirac chambers with experiments, as a result of which the molecule is damaged from them, toxins are often formed, the normal metabolism of the cell, its functioning is disrupted in general, and after a while, it dies, but even if the cell is strong in the spirit of the hero, it holds on to the last, it is still doomed, because due to DNA damage and gene mutations, normal cell division is impossible, this is perhaps the most dangerous There is a lot of radiation with a large dose of radiation, the affected cells are very much and whole can refuse only to find systems that are most susceptible to radiation, tissues in which active cell division is taking place, for example, bone marrow in which blood is processed or a consequence of the stomach that is expected by acid and should be actively regenerated, summing up, we can say radiation acts on the smallest scale in the structure of the human body, it is as if they fired at the exit of the fortress wall unprepared by shells and small small bullets so that the damage can be easily repaired, but if the field is huge, then the damage will be repaired and in the hands the wall will eventually become fragile and sooner or later will fall apart but you will never be able to hide from radiation with him it follows us everywhere in almost every substance there is a small fraction of unstable isotopes, so there is a little radioactive around us in seoul computers video cameras apples ban now, but even people in a person, for example, every second there are several thousand radioactive decays, it is another matter and the radiation intensity of course, the radiation of ordinary objects is very weak, well, and safe background radiation in general could be the driving force of the revolution, because perhaps it was thanks to her that the genes mutated so that we ended up like this it is cool to understand how to protect yourself from an unnecessary dose of radiation, the radiation attack will be easily saved by cardboard sheets, otherwise you can hide behind glass, but gamma radiation penetrates everything worse than an X-ray, so you can escape from it only for a thick layer of lead; another thing if the source gets in breathe out radioactive dust into your body or eat something then all types of radiation will act on the body from the inside and the consequences will be much more serious in terms of radiation there is no smell or color or

Exposure dose

The main characteristic of the interaction of ionizing radiation with a medium is the ionization effect. In the initial period of the development of radiation dosimetry, most often it was necessary to deal with X-rays propagating in the air. Therefore, the degree of air ionization 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 quite easy to measure, is called exposure dose.

The exposure dose determines the ionizing capacity of X-rays and gamma rays and expresses the radiation energy converted into 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.

Effective dose

Effective dose (E) is a value used as a measure of the risk of long-term effects of irradiation of the entire human body and its individual organs and tissues, taking into account their radiosensitivity. It represents the sum of the products of the equivalent dose in organs and tissues by the corresponding weighting factors.

The value of the radiation risk coefficient for individual organs

Weighted coefficients are established empirically and calculated in such a way that their sum for the whole organism is one. The units of measurement for the effective dose are the same as those for the equivalent dose. It is also measured in sievert or rem.

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

Effective and equivalent dose- these are standardized values, that is, values ​​that are a measure of damage (harm) from the impact of ionizing radiation on a person. Unfortunately, they cannot be directly measured. Therefore, operational dosimetric quantities have been introduced into practice, which are uniquely determined through the physical characteristics of the radiation field at a point, as close as possible to the standardized ones. The main operating quantity is the ambient dose equivalent (synonyms - ambient dose equivalent, ambient dose).

Ambient dose equivalentН * (d) - dose equivalent, which was created in a ball phantom ICRU (International Commission on Radiation Units) at a depth d (mm) from the surface in diameter parallel to the direction of radiation, in a radiation field identical to that considered in composition, fluence and energy distribution, but unidirectional and uniform, that is, the ambient dose equivalent H * (d) is the dose that a person would receive if he were at the place where the measurement is carried out. The unit of the ambient dose equivalent is the sievert (Sv).

Group doses

By calculating the individual effective doses received by individuals, one can come to 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 In addition, the following doses are distinguished:

• commitment - the expected dose, half a century dose. 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 irradiation of a group of people; unit - Sievert (Sv). The collective dose is defined as the sum of the products of average doses by the number of people in dose intervals. A collective dose can accumulate over a long time, not even one generation, but covering subsequent generations.
• threshold - the dose below which the manifestations of this radiation effect are not observed.
• maximum permissible doses (PDD) - the highest values ​​of the individual equivalent dose for a calendar year, at which uniform irradiation for 50 years cannot cause adverse changes in the state of health detected by modern methods (NRB-99)
• avoidable - the predicted dose due to a radiation accident, which can be prevented by protective measures.
• doubling - a dose that doubles (or 100%) the level of spontaneous mutations. The doubling dose is inversely proportional to the relative mutational risk. According to the currently available data, the value of the doubling dose for acute exposure is on average 2 Sv), and for chronic exposure it is about 4 Sv.
• biological dose of gamma-neutron radiation - a dose of gamma-radiation, which is equally effective in damaging the body, taken as a standard one. Equal to the physical dose of the given radiation multiplied by the quality factor.
• minimum lethal - the minimum dose of radiation that causes the death of all irradiated objects.

Dose rate

Dose rate(radiation intensity) - the increment of the corresponding dose under the influence of the given radiation per unit of time. Has the dimension of the corresponding dose (absorbed, exposure, etc.), divided by a unit of time. The use of various special units is allowed (for example, Sv / h, rem / min, mSv / year, etc.).

Units summary table