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In what units is radiation measured and what allowable doses are safe for humans. What radiation background is natural and what is acceptable. How to convert one unit of radiation measurement to another.

Permissible doses of radiation

• permissible level of radioactive radiation from natural radiation sources, in other words, the natural radioactive background, in accordance with regulatory documents, can be for five consecutive years not higher how

  0.57 µSv/h

In subsequent years, the background radiation should not exceed  0.12 µSv/h



• the maximum permissible total annual dose received from all man-made sources, is
  

The value of 1 mSv/year, in total, should include all episodes of anthropogenic impact of radiation on humans. This includes all types of medical examinations and procedures, including x-rays, dental x-rays, and so on. This also includes flying on airplanes, passing through security screening at the airport, receiving radioactive isotopes with food, and so on.

How is radiation measured?

To assess the physical properties of radioactive materials, the following quantities are used:

• radioactive source activity(Ki or Bq)
• energy flux density(W/m2)

To assess the effect of radiation per substance (non-living tissue), apply:

• absorbed dose(Gray or Rad)
• exposure dose(C/kg or X-ray)

To assess the effect of radiation on living tissue, apply:

• equivalent dose(Sv or rem)
• effective equivalent dose(Sv or rem)
• equivalent dose rate(Sv/h)

Assessment of the effect of radiation on non-living objects

The action of radiation on a substance is manifested in the form of energy that the substance receives from radioactive radiation, and the more the substance absorbs this energy, the stronger the effect of radiation on the substance. The amount of energy of radioactive radiation acting on a substance is estimated in doses, and the amount of energy absorbed by the substance is called - absorbed dose .

Absorbed dose is the amount of radiation absorbed by a substance. The SI system for measuring absorbed dose uses - Gray (Gr).

1 Gray is the amount of energy of radioactive radiation in 1 J, which is absorbed by a substance weighing 1 kg, regardless of the type of radioactive radiation and its energy.

1 Gray (Gy) \u003d 1J / kg \u003d 100 rad

This value does not take into account the degree of impact (ionization) on the substance of various types of radiation. A more informative value is exposure dose of radiation.

Exposure dose is a value that characterizes the absorbed dose of radiation and the degree of ionization of the substance. The SI system for measuring exposure dose uses - Coulomb/kg (C/kg).

1 C / kg \u003d 3.88 * 10 3 R

Used off-system unit of exposure dose - X-ray (R):

1 P \u003d 2.57976 * 10 -4 C / kg

Dose in 1 X-ray- this is the formation of 2.083 * 10 9 pairs of ions per 1 cm 3 of air

Assessment of the effect of radiation on living organisms

If living tissues are irradiated with different types of radiation having the same energy, then the consequences for living tissue will be very different depending on the type of radioactive radiation. For example, the consequences of exposure alpha radiation with an energy of 1 J per 1 kg of a substance will be very different from the effects of an energy of 1 J per 1 kg of a substance, but only gamma radiation. That is, with the same absorbed dose of radiation, but only from different types of radioactive radiation, the consequences will be different. That is, to assess the effect of radiation on a living organism, it is not enough just to understand the concept of absorbed or exposure dose of radiation. Therefore, for living tissues, the concept was introduced equivalent dose.

Dose equivalent is the dose of radiation absorbed by living tissue, multiplied by the coefficient k, which takes into account the degree of danger of various types of radiation. The SI system uses - Sievert (Sv) .

The off-system unit of equivalent dose used is rem (rem) : 1 Sv = 100 rem.

coefficient k
Type of radiation and energy range	Weight multiplier
Photons all energies (gamma radiation)	1
Electrons and muons all energies (beta radiation)	1
neutrons with energy < 10 КэВ (нейтронное излучение)	5
Neutrons from 10 to 100 keV (neutron radiation)	10
Neutrons from 100 keV to 2 MeV (neutron radiation)	20
Neutrons from 2 MeV to 20 MeV (neutron radiation)	10
Neutrons> 20 MeV (neutron radiation)	5
Protons with energies > 2 MeV (except for recoil protons)	5
alpha particles, fission fragments and other heavy nuclei (alpha radiation)	20

The higher the "coefficient k" the more dangerous the action of a certain type of radiation for the tissues of a living organism.

For a better understanding, we can give a slightly different definition of "equivalent dose of radiation":

Equivalent dose of radiation - this is the amount of energy absorbed by living tissue (absorbed dose in Gray, rad or J / kg) from radioactive radiation, taking into account the degree of impact (harm) of this energy on living tissues (K coefficient).

In Russia, since the accident in Chernobyl, the off-system unit of measurement μR/h, reflecting exposure dose, which characterizes the measure of ionization of the substance and the dose absorbed by it. This value does not take into account differences in the effects of different types of radiation (alpha, beta, neutron, gam, X-ray) on a living organism.

The most objective feature is equivalent dose of radiation, measured in Sieverts. To assess the biological effect of radiation, it is mainly used equivalent dose rate radiation, measured in Sieverts per hour. That is, it is an assessment of the impact of radiation on the human body per unit of time, in this case, per hour. Considering that 1 Sievert is a significant dose of radiation, for convenience, a multiple of it is used, indicated in micro Sieverts - μSv / h:

1 Sv/h = 1000 mSv/h = 1,000,000 µSv/h.

Values ​​that characterize the effects of radiation over a longer period, such as 1 year, may be used.

For example, in the radiation safety standards NRB-99/2009 (clauses 3.1.2, 5.2.1, 5.4.4), the norm of permissible exposure to radiation for the population from technogenic sources 1 mSv/year .

The regulatory documents SP 2.6.1.2612-10 (clause 5.1.2) and SanPiN 2.6.1.2800-10 (clause 4.1.3) indicate acceptable standards for natural sources of radioactive radiation, value 5 mSv/year . Used wording in the docs - "acceptable level", very fortunate, because it is not valid (that is, safe), namely acceptable .

But in the regulations there are contradictions on the permissible level of radiation from natural sources. If we sum up all the allowable standards specified in the regulatory documents (MU 2.6.1.1088-02, SanPiN 2.6.1.2800-10, SanPiN 2.6.1.2523-09), for each individual natural radiation source, we get that background radiation from all natural sources of radiation (including the rarest gas radon) should not exceed 2.346 mSv/year or 0.268 µSv/h. This is discussed in detail in the article. However, the regulatory documents SP 2.6.1.2612-10 and SanPiN 2.6.1.2800-10 indicate an acceptable rate for natural radiation sources of 5 mSv / year or 0.57 μS / hour.

As you can see, the difference is 2 times. That is, to the allowable standard value of 0.268 µSv/h, without any justification, a multiplying factor of 2 was applied. This is most likely due to the fact that in the modern world we are massively surrounded by materials (primarily building materials) containing radioactive elements.

Please note that in accordance with regulatory documents, the permissible level of radiation from natural sources radiation 5 mSv/year, and from artificial (technogenic) sources of radioactive radiation in total 1 mSv/year.

It turns out that when the level of radioactive radiation from artificial sources is more than 1 mSv / year, negative effects on humans can occur, that is, lead to diseases. At the same time, the standards allow that a person can live without harm to health in areas where the level is 5 times higher than the safe man-made exposure to radiation, which corresponds to the permissible level of natural radioactive background of 5 mSv / year.

According to the mechanism of its impact, types of radiation radiation and the degree of its effect on a living organism, natural and man-made sources of radiation they do not differ.

What do these rules say, though? Let's consider:

• the norm of 5 mSv / year indicates that a person during the year can receive the maximum dose of radiation absorbed by his body at 5 miles Sievert. This dose does not include all sources of anthropogenic impact, such as medical ones, from environmental pollution with radioactive waste, radiation leaks at nuclear power plants, etc.
• to estimate what dose of radiation is permissible in the form of background radiation at a given moment, we calculate: the total annual rate of 5000 μSv (5 mSv) is divided by 365 days a year, divided by 24 hours a day, we get 5000/365/24 = 0, 57 µSv/h
• the resulting value of 0.57 µSv/h is the maximum allowable background radiation from natural sources, which is considered acceptable.
• on average, the radioactive background (it has not been natural for a long time) ranges from 0.11 to 0.16 µSv/h. This is normal background radiation.

You can summarize the permissible levels of radiation in force today:

• According to the regulations, the maximum permissible level of radiation (radiation background) from natural sources of radiation can be 0.57 µS/h.
• If we do not take into account the unreasonable multiplying factor, and also do not take into account the effect of the rarest gas - radon, then we get that, in accordance with the regulatory documentation, normal radiation background from natural sources of radiation should not exceed 0.07 µSv/h
• the maximum allowable standard total dose received from all man-made sources, is 1 mSv/yr.

It can be confidently stated that the normal, safe radiation background is within 0.07 µSv/h , acted on our planet before the industrial use of radioactive materials by humans, nuclear energy and nuclear weapons (nuclear tests).

And as a result of human activity, we now consider acceptable radiation background is 8 times higher than the natural value.

It is worth considering that before the beginning of the active development of the atom by man, mankind did not know what cancer was in such a massive amount, as it happens in the modern world. If before 1945 cancers were recorded in the world, then they could be considered isolated cases compared with statistics after 1945.

think about it , according to WHO (World Health Organization), in 2014 alone, about 10,000,000 people died on our planet from cancer, which is almost 25% of the total number of deaths, that is in fact, every fourth death on our planet is a person who died of cancer.

Also, according to the WHO, it is expected that in the next 20 years, the number of new cancer cases will increase by about 70% compared to today. That is, cancer will become the main cause of death. And no matter how carefully, the government of states with nuclear energy and nuclear weapons would not mask the general statistics on the causes of death from cancer. It can be confidently stated that the main cause of cancer is the impact on the human body of radioactive elements and radiation.

For reference:

To convert µR/h to µSv/h You can use the simplified translation formula:

1 µR/h = 0.01 µSv/h

1 µSv/h = 100 µR/h

0.10 µSv/h = 10 µR/h

The indicated conversion formulas are assumptions, since μR/h and μSv/h characterize different values, in the first case it is the degree of ionization of the substance, in the second it is the absorbed dose by living tissue. This translation is not correct, but it allows at least an approximate assessment of the risk.

Radiation Conversion

To convert values, enter the desired value in the field and select the original unit of measurement. After entering the value, the remaining values ​​in the table will be calculated automatically.

The radioactivity of a substance is characterized by the number of decays per unit time. The greater the number of decays per unit time, the higher the activity of the substance. The rate of radioactive decay is determined by the value of the half-life (T), i.e., the period of time during which the activity of a radioactive element is reduced by half. For each isotope, the rate of radioactive decay, as will be shown below, is a very important indicator for the hygienic assessment of working conditions and the choice of special protective measures.

To measure radioactivity, a unit is adopted - decay per second, as well as an off-system unit - curie (k), i.e., the activity of such an amount of radioactive substance in which 3.7 10 10 decays occur in 1 second. In practice, units derived from the curie are used: millicurie (mk), microcurie (mkk). The concentration of radioactive substances in air and water is measured in curie per 1 l - k / l.

Gamma activity is expressed in milligram equivalents of radium. It is the gamma equivalent of a radioactive preparation, whose γ-radiation under identical conditions creates the same dose rate as γ-radiation of 1 mg of radium of the State Standard of Radium of the USSR with a platinum filter 0.5 mm thick. A point source of 1 mg of radium in equilibrium with decay products after filtration through a platinum filter 0.5 mm thick of platinum produces a dose rate of 8.4 r per hour at a distance of 1 cm in air.

Roentgen (p) is taken as the unit dose of X-rays and γ-rays. One roentgen is a dose that in 1 cm 2 of air at 0 ° and a pressure of 760 mm Hg. Art. forms ions with a total charge of one electrostatic unit of the amount of electricity of each sign. In practice, x-ray derivatives are used: 1 p \u003d 10 3 mr (milliroentgen) \u003d 10 6 mcr (micro-roentgen). To characterize the distribution of dose over time, the concept of dose rate is introduced: r/h, r/min, r/s, mr/h, mr/min, mr/s, etc.

Previously, the unit of absorbed dose and radiation dose (for all types of radiation) used the physical equivalent of the roentgen (fair). Pair - the dose of any ionizing radiation at which the energy absorbed in 1 g of a substance is equal to the energy loss for ionization created in it by a dose of 1 r of x-rays or y-rays; 1 fair for air is equal to 84 erg/g, for biological tissues - 93 erg/g.

With the same absorbed dose, the biological effect of different types of radiation is not the same; it can be expressed by the following quantities (relative biological effectiveness - obe):

Thus, the biological effect of exposure to a-radiation is 10 times greater, thermal neutrons - 3 times, fast neutrons and protons - 10 times greater than the effect of exposure to y- and X-rays.

Various biological effects mainly depend on the density of ionization created in the tissues by one or another ionizing radiation. At the suggestion of the International Congress of Radiologists in 1953, the unit rad was adopted as the unit of absorbed dose of ionizing radiation energy per unit mass of the irradiated substance. For all types of ionizing radiation, rad corresponds to an absorbed energy of 100 ergs per 1 g of any substance. To take into account the biological effect of various types of radiation, another unit was introduced - the biological equivalent of a rad - rem. For 1 rem, such an absorbed dose of any type of ionizing radiation is taken, which causes the same biological effect as 1 rad of x-rays or y-rays.

The term "relative biological efficiency" is usually used in the comparative assessment of the effects of radiation in radiobiology. Since the value of OBE depends on a number of reasons - radiation energy, criteria for biological action, etc., when solving problems of radiation safety, the so-called quality factors - QC are used, which are quantities that show the dependence of the biological effect of chronic irradiation of the body on the transfer of energy per unit the path length of a particle or quantum. To determine the absorbed dose in rem (Drem), it is necessary to multiply the dose in rad (Drad) by the quality factor and the distribution factor (CR), which takes into account the effect of the inhomogeneous distribution of radioactive isotopes.

Dber \u003d Drad · KK · KR.

Contamination of working surfaces and equipment, hands, overalls and other items with α- and β-emitters is expressed in the number of particles emitted from an area of ​​1 cm 2 per 1 minute.

Radiation is no longer something unknown to humans. In the modern world, if not everything, then quite a lot is known about it. Scientists are constantly studying this radiation to make it as safe as possible for humans. After all, before the terrible tragedy at the Chernobyl nuclear power plant, few people imagined how destructive radiation from the energy released as a result of an atomic reaction could be. From that moment on, in the USSR, every person had to know what radiation is measured in and how to minimize the harm it causes to the body.

Radiation: what is it?

Translated from Latin, the word "radiation" means "radiance". This term includes a general understanding of the propagation of energy in space in the form of various waves and particles. Scientists refer to radiation as UV radiation, thermal or light. They are harmless to humans in limited dosage. But ionizing is a serious source of danger for all living organisms on the planet, they usually mean it when they talk about radiation.

Ionizing radiation: description

Ionizing radiation can be represented as a stream of particles capable of ionizing everything living and non-living. In the process of exposure to biological organisms of various kinds, free radicals are released, which destroy protein bonds and lead to irreversible changes called mutations. In cases of high doses of ionizing radiation, radiation sickness occurs, characterized by complete destruction of internal organs and in most cases leading to death. Ionizing radiation equally detrimental effect on all living organisms without exception. Scientists are still studying all aspects of the effects of radiation on humans and animals.

Radioactivity occurs due to the destruction of nuclei in atomic particles, as a result of this process a large amount of radiation is released. The danger of radiation lies in the fact that it cannot be seen with the eye. It does not smell and at first its effect on the body is almost imperceptible. If you do not know in what units radiation is measured and how to measure it, then you can be in the dark for a long time about the detrimental effect on you.

Types of ionizing radiation

To understand what the level of radiation is measured in, you must first find out what kind of radiation we are talking about. The fact is that ionizing radiation can be of several types:

• alpha rays - practically safe at a distance of two to three meters, in this case, radiation cannot penetrate the skin;
• beta rays - you can protect yourself from them with a distance and several layers of clothing, but with close contact, radiation has a high penetrating power;
• gamma and x-ray radiation - it is highly penetrable, with close contact it completely shines through the human body (you can protect yourself from it by distance and objects containing petroleum products);
• neutron - is one of the most dangerous for humans, as it has a high penetrating power.

Each of the types of radiation at a high dosage harms the body. But scientists still cannot say for sure which rays are safe for the body, although the general indicators of acceptable norms have been deduced. A little later, we will return to the issue of acceptable dosage and find out how the dose of radiation is measured.

Radiation and Radioactivity: Definition and Differences

Before dealing with the question of how and in what radiation is measured, it is necessary to better understand the terminology associated with this topic. The fact is that many people often confuse the concepts of "radiation" and "radioactivity". Despite the similarity, there are significant differences between these terms.

Radiation can be represented as a stream of particles in the surrounding space. Before any object is encountered on the way, the radiation will be randomly distributed in space. But radioactivity is understood as the ability of an object to absorb radiation and subsequently independently emit it.

Sources of radiation

If all of the above scared you, and you are worried about the radiation background around you, then it's time for you to find out what radiation is measured in. But don't panic. Keep in mind that there are a lot of sources of radiation around us. And not all of them harm our body. Almost all objects on planet Earth are radioactive - this is their natural state. In general, all sources of radiation are divided into:

• natural;
• artificial.

We will now discuss them in more detail.

natural sources

Natural radioactivity is characteristic of all the planets of the solar system. We in one way or another receive certain doses of radiation that do not cause significant harm to our body. Although in recent years, scientists have been inclined to conclude that even natural radioactivity, which affects people every day, makes its own adjustments to the development of certain diseases. According to one version, in areas with an increased natural radiation background, the statistics of oncological diseases are several percent higher than in other parts of the planet. What is the source of natural radiation? And how is radiation measured?

Scientists distinguish three types of natural radiation:

1. Solar and space

Space and our Sun are the most powerful source of radiation. It falls on the Earth in a powerful continuous stream, the only protection for all life on the planet is the atmosphere. It acts as a barrier and allows only small doses of radiation to reach the surface of the planet. But the higher a person is above sea level, the greater the dose of radiation he receives. According to some reports, the dose of radiation during an airplane flight is up to ten times higher than the norm.

It's no secret that the earth's crust contains a large amount of radioactive substances. They are located in the bowels of the planet and come to the surface mainly in connection with the extraction of minerals. Quite often, modern building materials have increased radioactivity, and many soil fertilizers differ in the same way. In this regard, a person can receive external and internal exposure.

3. Radon gas

Enough scientific papers and books have already been written about the benefits and dangers of radon. It is a heavy gas found in the bowels of the earth. Through cracks in the earth's crust, it comes to the surface and accumulates in some places. In large quantities, it is very dangerous to humans. It enters modern houses from deep-sea wells, cracks and accumulates in basements or on the first floors of high-rise buildings. Experts advise to ventilate the premises more often in order to reduce the concentration of radon and protect yourself from the consequences of its exposure.

artificial sources

Human activity in the age of high technology is often accompanied by the creation of artificial sources of radiation. They are used in many branches of medicine and industry, modern military technology is also impossible to imagine without the use of nuclear energy.

Quite often, people do not know how close they are to sources of such radiation. For example, many companies hide from the media the location of the landfills where nuclear waste is buried. Near them, suburban villages or country houses may well be built.

The only way to get the necessary information and protect the family from living in a dangerous area is to measure the radioactive background with special devices designed for this purpose. Before buying such a device, you need to find out a few nuances, in particular, to find out what are the permissible doses of radiation and how radiation is measured. The units of measurement of ionizing radiation should be known to all modern people. We will talk about this in more detail now.

What is radiation measured in: units

It is impossible to talk separately about the units of measurement of radiation without mentioning the dose of radiation. These concepts are very closely related and constantly intersect. The dose of radiation is considered to be the amount of radiation absorbed by the body. Doses differ in units of measurement and in the quality of the emitted waves. For example, the impact of gamma rays is usually measured in Roentgens, and quite often the time interval in which the impact occurred is also indicated - an hour or a minute.

There is a dose absorbed by a substance - it is measured in Grays. It can be used to determine the degree of harm that radiation caused to the tissues of a living organism. Most often, when talking about radiation and its doses, people want to find out exactly the degree of danger to themselves and their loved ones. In this case, the absorbed dose of radiation is calculated multiplied by a coefficient that takes into account the degree of harm of various types of radiation. The unit of equivalent dose is the Sievert. This is a fairly large value, so micro-Sieverts are often used in science. For example, one Sievert is equal to one hundred Roentgens.

Dosimeters help in determining radiation. They are for industrial and domestic purposes. Mostly household appliances are on sale, they are available to absolutely everyone. According to them, everyone independently determines the danger to themselves based on the permissible level of radiation, which is fixed in the legislative framework of each state. In Russia, the natural radioactive background cannot exceed 0.57 micro-Sievert per hour, and the maximum harmless dose of radiation per year is equal to one micro-Sievert per hour. This indicator includes natural exposure and that which a person receives as a result of undergoing various medical procedures or in connection with professional activities.

In what units is solar radiation measured?

The system of calculations that we have already described is not suitable for our luminary. Let's find out what solar radiation is measured in. Scientists call this the flow of energy that is converted into heat. Therefore, it is measured in calories or watts. In this case, the amount of energy that falls on one square centimeter or meter of surface in one minute is taken as the basis. Scientists have deduced some solar constant - 1328 watts per square meter, from which they start in determining solar activity. But in fact, this constant is not stable, it changes all the time and is used only for approximate calculations.

It is not worth living in fear of radioactive exposure - it will be present in our lives all the time. Therefore, every responsible person must learn to coexist with this phenomenon and, of course, constantly measure the radiation background with a dosimeter. This device should be in any family.

Radiation (or ionizing radiation) is a set of different types of physical fields and microparticles that have the ability to ionize substances.

Radiation is divided into several types and is measured using various scientific instruments specially designed for this purpose.

In addition, there are units of measurement, exceeding which can be fatal to humans.

The most accurate and reliable way to measure radiation

With the help of a dosimeter (radiometer) it is possible to measure the intensity of radiation as accurately as possible, to examine a certain place or specific objects. Most often, devices for measuring the level of radiation are used in places:

1. Approximate to areas of radiation radiation (for example, near the Chernobyl nuclear power plant).
2. The planned construction of a residential type.
3. In unexplored, unexplored areas during hikes, travels.
4. With the potential purchase of housing stock.

Since it is impossible to clean the territory and objects located on it from radiation (plants, furniture, equipment, structures), the only sure way to protect yourself is to check the level of danger in time and, if possible, stay away from sources and contaminated areas as far as possible. Therefore, under normal conditions, household dosimeters can be used to check the area, products, and household items, which successfully identify the hazard and its doses.

Rationing of radiation

The purpose of radiation control is not just to measure its level, but also to determine whether the indicators correspond to established standards. Criteria and standards for a safe level of radiation exposure are prescribed in separate laws and generally established rules. The conditions for the content of technogenic and radioactive substances are regulated for the following categories:

• food
• Air
• Building materials
• computer technology
• medical equipment.

Manufacturers of many types of food or industrial products are required by law to prescribe criteria and indicators of compliance with radiation safety in the conditions and certification documents. The relevant government services quite strictly monitor various deviations or violations in this regard.

Radiation units

It has long been proven that background radiation is present almost everywhere, but in most places its level is recognized as safe. The level of radiation is measured in certain indicators, among which the main ones are doses - units of energy absorbed by a substance at the time of passage of ionizing radiation through it.

The main types of doses and their units of measurement can be listed in the following definitions:

1. Exposure dose- created with gamma or x-ray radiation and shows the degree of air ionization; non-systemic units of measurement - rem or "roentgen", in the international SI system it is classified as "coulomb per kg";
2. Absorbed dose– unit of measurement – ​​gray;
3. Effective dose- is determined individually for each organ;
4. Dose equivalent– depending on the type of radiation, calculated from the coefficients.

Radiation radiation can only be determined and instruments. At the same time, there are certain doses and established norms, among which the permissible indicators, negative doses of effects on the human body and lethal doses are strictly specified.

Radiation Safety Levels

For the population, certain levels of safe values ​​of absorbed radiation doses are established, which are measured by a dosimeter.

Each territory has its own natural radiation background, but a value equal to approximately 0.5 microsievert (µSv) per hour (up to 50 microroentgen per hour) is considered safe for the population. Under normal background radiation, the safest level of external exposure of the human body is considered to be up to 0.2 (µSv) microsievert per hour (a value equal to 20 microroentgens per hour).

Most upper limit permissible radiation level - 0.5 µSv — or 50 µR/h.

Accordingly, a person can tolerate radiation with a power of 10 μS / h (microsievert), and when the exposure time is reduced to a minimum, radiation of several millisieverts per hour is harmless. This is how fluorography works, X-rays - up to 3 mSv. A snapshot of a diseased tooth at the dentist's office - 0.2 mSv. The absorbed radiation dose has the ability to accumulate over a lifetime, but the amount should not cross the threshold of 100-700 mSv.

Many people face difficulties in determining the units of measurement of radioactive radiation and the practical use of the values ​​obtained. Difficulties arise not only because of their great diversity: becquerels, curies, sieverts, roentgens, rads, coulombs, rhemes, etc., but also due to the fact that not all quantities used are related by multiple ratios and, if necessary, can be translated from one to another.

How to figure it out?

Everything is quite simple, if we separately consider the units associated with radioactivity as a physical phenomenon, and the quantities that measure the impact of this phenomenon (ionizing radiation) on living organisms and the environment. And also, if we do not forget about non-systemic units and units of radioactivity, operating in the SI system (International System of Units), which was introduced in 1982 and is mandatory for use in all institutions and enterprises.

Non-systemic (old) unit of measurement of radioactivity

Curie (Ci) is the first unit of radioactivity, measuring the activity of 1 gram of pure radium. Introduced since 1910 and named after the French scientists K. and M. Curie, it is not associated with any measurement system and has recently lost its practical significance. In Russia, the curie, despite the current SI system, is allowed for use in the field of nuclear physics and medicine without a time limit.

Units of radioactivity in the SI system

The SI uses a different quantity, the becquerel (Bq), which measures the decay of one nucleus per second. Becquerel is more convenient in calculations than curies, since it has not such large values ​​and allows you to determine its amount without complex mathematical operations on the radioactivity of a radionuclide. Having calculated the number of decays of 1 g of radon, it is easy to establish the ratio between Ki and Bq: 1 Ki = 3.7 * 1010 Bq, and also determine the activity of any other radioactive element.

Measurement of ionizing radiation

With the discovery of radium, it was discovered that the radiation of radioactive substances affects living organisms and causes biological effects similar to those of X-ray radiation. There was such a thing as the dose of ionizing radiation - a value that allows you to evaluate the impact of radiation exposure on organisms and substances. Depending on the characteristics of exposure, equivalent, absorbed and exposure doses are distinguished:

1. Exposure dose - an indicator of air ionization that occurs under the action of gamma and X-rays, is determined by the number of radionuclide ions formed in 1 cubic meter. see air under normal conditions. In the SI system, it is measured in coulombs (C), but there is also an off-system unit - the roentgen (R). One roentgen is a large value, therefore it is more convenient in practice to use its millionth (μR) or thousandth (mR) fractions. The following ratios were established between exposure dose units: 1 Р = 2.58.10-4 C/kg.
2. Absorbed dose - the energy of alpha, beta and gamma radiation absorbed and accumulated by a unit mass of a substance. In the international SI system, the following unit of measurement was introduced for it - gray (Gy), although an off-system unit - rad (P) is still widely used in certain areas, for example, in radiation hygiene and radiobiology. Between these values ​​there is such a correspondence: 1 Rad \u003d 10-2 Gy.
3. Equivalent dose - the absorbed dose of ionizing radiation, taking into account the degree of its effect on living tissue. Since the same doses of alpha, beta or gamma radiation cause different biological damage, the so-called QC-quality factor has been introduced. To obtain an equivalent dose, it is necessary to multiply the absorbed dose received from a certain type of radiation by this coefficient. The equivalent dose is measured in bers (Rem) and sieverts (Sv), both of these units are interchangeable, converted from one to another in this way: 1 Sv \u003d 100 Rem (Rhm).

The SI system uses the sievert, which is the equivalent dose of a specific ionizing radiation absorbed by one kilogram of biological tissue. To convert grays to sieverts, one should take into account the coefficient of relative biological activity (RBE), which is equal to:

• for alpha particles - 10-20;
• for gamma and beta radiation - 1;
• for protons - 5-10;
• for neutrons with speeds up to 10 keV - 3-5;
• for neutrons with a speed greater than 10 keV: 10-20;
• for heavy nuclei - 20.

Rem (biological equivalent of X-ray) or rem (in English rem - Roentgen Equivalent of Man) is a non-systemic unit of equivalent dose. Since alpha radiation causes more damage, to obtain a result in rhemes, it is necessary to multiply the measured radioactivity in rads by a factor of twenty. When determining gamma or beta radiation, no conversion is required, since the rhemes and rads are equal to each other.