This article is devoted to the topic of absorbed doseradiation (ionization), ionizing radiation and their types. It contains information on diversity, nature, sources, methods of calculation, units for measuring the absorbed dose of radiation, and much more.
The dose of radiation is the quantity that is usedsuch sciences as physics and radiobiology, in order to assess the degree of exposure to radiation of the ionizing type on the tissues of living organisms, processes of their vital activity, and also on substances. What is called the absorbed dose of radiation, what is its significance, form of influence and variety of forms? It is mainly represented in the form of interaction between the medium and ionizing radiation, but is called the ionization effect.
The absorbed dose of radiation has its own methods andunit of measurement, and the complexity and diversity of processes under the influence of radiation give rise to some species diversity in the forms of absorbed dose.
Ionizing radiation is the flow of varioustypes 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 apply to this kind of radiation, nor does it include infrared radiation and radio frequencies, which is due to their small amount of energy, which is not enough to create atomic and molecular ionization in the ground state.
The absorbed dose of ionizing radiation canmeasured in different SI units, and depends on the nature of the radiation. The most significant types of radiation: gamma radiation, beta particles of positrons and electrons, neutron, ion (including alpha particles), X-ray, electromagnetic with short waves (high energy photons) and muon.
The nature of ionizing radiation sources canbe diverse, for example: spontaneously occurring radionuclide decay, thermonuclear reactions, rays from space, artificially created radionuclides, nuclear-type reactors, particle accelerator, and even an X-ray apparatus.
Depending on the mechanism by whichinteract, matter and ionizing radiation, it is possible to distinguish the direct flow of particles of a charged type and radiation that acts indirectly, in other words, the photon or proton flux of neutral particles of the flow. The formation device makes it possible to isolate the primary and secondary form of ionizing radiation. The power of the absorbed radiation dose is determined according to the type of radiation to which the substance is exposed, for example, the force of the effective dose of rays from space on the earth's surface, outside the shelter, is 0.036 μSv / h. It is also worth noting that the type of measurement of the dose of radiation and its index depend on the sum of a number of factors, speaking of cosmic rays, it also depends on the latitude of the geomagnetic form and the position of the cycle of eleven-year activity of the sun.
The range of energy of ionizing particles is in the range of values from a couple of hundred electron volts and reaches the values of 1015-20 electron-volt. The length of the run and the ability to penetrate can vary greatly, and lie within a few micrometers, up to thousands or more kilometers.
The ionization effect is considered to be the maincharacteristic of the form of interaction of radiation with the medium. At the initial period of the formation of radiation dosimetry, the study was mainly studied, the electromagnetic waves of which were within the limits of the parameters between ultraviolet and gamma radiation, because it is widespread in the air. Therefore, the quantitative measure of the radiation for the field was the level of air ionization. Such a measure became the basis for creating an exposure dose, determined by air ionization under normal atmospheric pressure, while the air itself must be dry.
Exposure absorbed dose of radiation servesa means of determining the ionizing radiation capabilities of X-rays and gamma rays, shows the radiated energy that, having undergone the transformation, has become the kinetic energy of charged particles in the proportion of the air mass of the atmosphere.
Unit of absorbed dose of radiation forExposure type is a pendant, a component of the SI system divided by kg (Cl / kg). The type of the non-system unit of measure is X-ray (P). One pendant / kg corresponds to 3876 roentgens.
The absorbed dose of the formulation, as a clear definition,became necessary to man in connection with the variety of possible forms of the effect of radiation on the tissues of living beings and even inanimate structures. Expanding, a certain range of ionizing species of energy has shown that the degree of influence and impact can be very diverse and not subject to the usual definition. The beginning of chemical-physical changes in tissues and substances subjected to irradiation can only a specific amount of absorbed energy of radiation of ionizing type. The very number necessary to trigger such changes depends on the type of radiation already. The absorbed dose of i-tion arose precisely for this reason. In fact, this is an energy value that has been absorbed by a unit of matter and corresponds to a ratio of the energy of the ionizing type that was absorbed and the mass of the subject or object absorbing radiation.
Measure absorbed dose using the gray unit(Гр) - an integral part of the C system. One gray is the dose that can transmit one joule of ionizing radiation to 1 kilogram of mass. Rad is an extrasystem unit of measurement, with a value of 1 Gy corresponds to 100 rad.
Artificial irradiation of animal tissues andof plant origin clearly demonstrated that different types of radiation, being in the same absorbed dose, can differently affect the body and all the biological and chemical processes taking place in it. This is due to the difference in the amount of ions produced by lighter and heavier particles. For the same path along the tissue the proton can create ions more than the electron. The more closely the particles are collected as a result of ionization, the more damaging the radiation will be to the organism, under the conditions of the same absorbed dose. It was in accordance with this phenomenon, the difference in the strength of the effect of various types of radiation on the tissue, that the designation of an equivalent dose of radiation was introduced into use. The equivalent dose of absorbed radiation is the data on the radiation received by the body, calculated by multiplying the absorbed dose rate and the special coefficient, which is called the relative biological efficiency factor (RBE). But it is also often referred to as a quality factor.
Units of absorbed dose of radiation equivalenttype are measured in SI, namely in sievert (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 1 Gy of photon-type radiation. Baer - is used as an off-system measuring indicator of the biological (equivalent) absorbed dose. 1 Sv corresponds to one hundred beers.
The effective dose is an indicator of the 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 his individual radiosensitivity. The absorbed dose of radiation is equal to the product of the biological dose in parts of the body for a certain weighted coefficient.
Different human tissues and organs havedifferent radiation susceptibility. Some organs may, at a single value of the equivalent absorbed dose rate, be more likely to develop cancer than others, for example, the chance of such a disease in the thyroid is less than in the lungs. Therefore, a person uses the created coefficient of radiation risk. CRC is a tool for determining the dose of i-tion affecting the organs or tissues. The total index of the degree of effect on the body of the effective dose is calculated by multiplying the number of the corresponding biological dose in the CRC of a particular organ, tissue.
There is a notion of a group dose of absorption,which is the sum of the individual set of effective dose values in a particular group of subjects over a certain time interval. Calculations can be made for any settlements, including states or whole continents. To do this, multiply the average effective dose and the total number of subjects exposed to radiation. Measure such an indicator of the absorbed dose with the help of man-sievert (man-Sv.).
In addition to the above-mentioned forms of absorbed doses,there is also a commision, threshold, collective, preventable, maximum permissible biological dose of gamma-neutron radiation type, lethal-minimal.
Indicator of radiation intensity - substitutiona specific dose under the influence of a certain radiation for a time measuring unit. This value is inherent in the dose difference (equivalent, absorbed, etc.) divided by the unit of time. There are many specially created units.
The absorbed radiation dose is determined bya formula suitable for a specific 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 measuring units are used. Examples of measuring units are:
There are other measuring units corresponding to other forms of absorbed radiation dose.
Analyzing these articles, we can conclude thatthere are many types, both the ionizing ionization itself, and the forms of its influence on the substances of living and inanimate nature. All of them are measured, as a rule, in the system of SI units, and each type corresponds to a certain system and non-system measuring unit. Their source can be very diverse, both natural and artificial, and the radiation itself plays an important biological role.
