This article is devoted to the topic of absorbed dose of radiation (i-niya), 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 type 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 of radiation has its own methods and units of measurement, and the complexity and diversity of the processes occurring when exposed to radiation give rise to some species diversity in the forms of the absorbed dose.
Ionizing form of radiation
Ionizing radiation is a streamvarious types of elementary particles, photons or fragments formed as a result of atomic fission and capable of causing ionization in matter. Ultraviolet radiation, like the visible form of light, does not belong to this type of radiation, nor does it include infrared type radiation and emitted by radio bands, which is associated with 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, neutron, ion (including alpha particles), x-ray, short wave electromagnetic (high energy photons) and muon.
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 ionizing radiation works
Depending on the mechanism by which matter and ionizing radiation interact, it is possible to distinguish a direct flow of particles of a charged type and radiation that acts indirectly, in other words,photon or proton flux, neutral particle flux. 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 ranges from a couple of hundred electron volts to 1015-20 electron volts. Mileage and penetration can vary greatly, ranging from a few micrometers to thousands of kilometers or more.
Introduction to exposure dose
The ionization effect is considered the main characteristic of the form of interaction of radiation with 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. This measure became the basis for creating an exposure dose determined by the ionization of air inconditions 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 capabilities of X-ray and gamma-ray radiation, 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 exposure type absorbed dose unit is the coulomb, the SI component, divided by kg (C/kg). The type of non-systemic unit of measurement is roentgen (P). One pendant/kg corresponds to 3876 roentgens.
Amount consumed
The absorbed dose of radiation, as a clear definition, has become necessary for a person due to the variety of possible forms of exposure to a particular radiation on 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 been absorbed 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.
Measure the absorbed dose 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 value 1 Gy corresponds to 100 rad.
Absorbed dose in biology
Artificial irradiation of animal and plant tissues has 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 the destructive effect of radiation on the body will be, 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 equivalent dose is the amount of radiation received by the body, calculated by multiplying the absorbed dose and a specific factor called the relative biological effectiveness factor (RBE). But it is also often referred to as the quality factor.
The units of absorbed dose of equivalent type of radiation are measured in SI, namely sieverts (Sv). One Sv is equal to the correspondingdose 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 - used as an off-system measuring indicator of the biological (equivalent) absorbed dose. 1 Sv corresponds to one hundred rems.
Effective dose form
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 body parts 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 a group absorption dose, which is the sum of an individual set of effective dose values in a particular group of subjects for a certain timegap. 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.
Strength of dose exposure and units of measurement
Indicator of irradiation intensity - 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 purpose built units.
The absorbed dose of radiation is determined by the 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:
- Integral view - gray kilogram in SI, outside the system is measured in rad grams.
- Equivalent form - sievert in SI, measured outside the system - in rems.
- Exposition view - coulomb-kilogram in SI, measured outside the system - in roentgens.
There are other units of measurement corresponding to other forms of absorbed radiation dose.
Conclusions
Analyzing these articles, we can conclude that there are many types of both the most ionizing emission and the forms of its impact on living and inanimate substances. 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.
