Computed tomography has become the main method of early diagnostics of COVID-19 during the pandemic of the novel coronavirus infection. Based on results of computed tomography of the chest it is possible to diagnose viral pneumonia associated with COVIS-19, to quickly assess the lung damage volume and severity of changes, to perform quick routing of patients and to start antiviral treatment. Hence, 2020 was associated with a rapid increase in the number of computed tomography examinations with corresponding changes in the structure of X-ray diagnostics. The aim of the current study was to evaluate the impact of the pandemic of the novel coronavirus infection on the structure of X-ray diagnostics and collective doses from medical exposure in the Russian Federation in 2019-2020. The study was based on the results of analysis of the federal state statistical surveillance forms №3-DOZ and №30 as well as on the data on Covid-19 morbidity in the regions of the Russian Federation. The results of the study indicate that there were no significant changes in the structure of X-ray diagnostics in 2020 compared to 2019 except for the increase in the number of computed tomography examinations. Their contribution to the total number of X-ray examinations has increased to 8,2% in 2020 compared to 4,6% in 2019. Contribution of other imaging modalities to the total number of X-ray examinations has not changed significantly. In 2020 the number of X-ray examinations decreased by 20% in average, varying from 6% for diagnostic nuclear medicine to 42% for interventional examinations. At the same time, the number of computed tomography examinations has rapidly increased by 60%. The structure of collective dose from medical exposure has significantly changed in 2020. Contribution of computed tomography to the collective dose in 2020 accounted for to 74% compared to 57% in 2019. Contribution of other imaging modalities has decreased by the factor of 1,5-2. Contribution of radiography examinations has decreased to 10,5% compared to 19% in 2019. Collective doses have correspondingly decreased by 20-30% for all imaging modalities except for computed tomography. Collective dose from computed tomography has increased by 71% compared to 2019. The number of all X-ray examinations in the Russian Federation has decreased by 12%: from 294 million in 2019 to 258 million in 2020. Collective dose from medical exposure has rapidly increased in 2020 by 30% to 115 thousand man. -Sv compared to 88 thousand man. -Sv in 2019. In average, in regions of the Russian Federation in 2020 each second computed tomography examination has been performed as a part of COVID-19 diagnostics with 2,3 computed tomography examinations per person infected with COVID.

The paper presents results of comparative analysis of the regulatory framework of the Russian Federation with the recommendations and requirements of international organizations in relation to the exposure of population and workers to natural sources of radiation. It is shown that the approaches to radiation safety related to exposure to natural sources of radiation in the Russian regulatory documents are somewhat more consistent with the provisions of the EU Council Directive 2013/59/Euratom than with the recommendations of the IAEA Basic Safety Standards. Analysis of requirements of Russian and international documents is the first step on the way to assess the possibility of implementation of recommendations of international organizations into the Russian regulatory documents and to develop the proposals on harmonization of requirements for control of the exposure of population and workers to natural sources of radiation.

Individual dosimetry monitoring of occupational internal exposure due to plutonium intake is performed by the bioassay method which measures the plutonium isotopes in daily urine samples. Then, to estimate normalized values (committed effective dose and intake), biokinetic and dosimetry models are used. The currently valid major instruments of radiation safety in the Russian Federation are based on the requirements and approaches outlined in Publications 68 and 78 of the International Commission on Radiobiological Protection. In implementing the requirements of Publication 130 there will be a need for updating the Russian guidance documents to the new requirements. The purpose of this study was the analysis of correspondence of the current system of individual monitoring of internal exposure caused by plutonium intake to the relevant recommendations of the International Commission on Radiobiological Protection outlined in Publication 130 by the example of the FSUE “Mayak PA” production conditions. As a result of the study, the values of annual limit of plutonium intake were determined based on new biokitetic and dosimetry models, and the measured values were calculated during the current dosimetry monitoring corresponding to the value of committed effective dose limit for Category A, B personnel and women under 45 years of age. It was found that following the introduction of new requirements of the International Commission on Radiobiological Protection for Type M compounds, an intake of more than 1/4 of annual limit of plutonium intake could be determined within a year after intake using the method of alpha spectrometry. To determine an intake of 1/20 of annual limit of intake at the recommended interval of 180 days between measurements, it is necessary to use inductively-coupled plasma mass spectrometry. For the personnel working with insoluble compounds of plutonium, an intake of one annual limit of intake and 1/4 of annual limit of intake can be determined using mass spectrometry, and 1/20 of annual limit of intake can be determined using only a more sensitive method.

During a stay in a radioactively contaminated forest, a person is inevitably exposed to ionizing radiation from the man-made radionuclides. The purpose of this study was to evaluate the external component of the annual effective dose due to exposure in the forests contaminated following the Chernobyl accident. The study was conducted in the south-western districts of the Bryansk region of Russia in the period 2015–2021. Field (in situ) gamma spectrometric measurements were carried out on 46 forest plots located in the areas of 27 settlements. As of 01.01.2017, the officially established values of soil contamination density with ¹³⁷Cs in the territory of the settlements themselves were in the range from 33 to 2050 kBq/m² . According to the field gamma spectrometry, the density of soil contamination with ¹³⁷Cs on the forest plots varied from 21 to 1930 kBq/m² . The density of soil contamination with ¹³⁷Cs in forest was in good agreement with the officially established level of soil contamination with ¹³⁷Cs in the nearby settlement: the ratio of one indicator to another ranged from 0.70 to 1.32 (mean = 0.94; median = 0.95). The scatter in the measured values of the ambient dose equivalent rate from ¹³⁷Cs was quite significant: more than one order of magnitude, from 31 to 2700 nSv/h. The variability of the ambient dose equivalent rate from natural radionuclides was relatively small: from 13 to 29 nSv/h. Based on the obtained experimental data and on published values of the duration of human stay in forest, the annual effective dose to selected groups of population was estimated. The dose from natural radionuclides, even in the case of a prolonged stay in the forest (1400 hours per year for foresters), did not exceed 0.02 mSv/year. The estimated values of the effective dose from ¹³⁷Cs varied very widely from 0.001 to 1.9 mSv/year, depending on the selected forest plot and population group. On the whole, the data obtained indicate that the officially established values of the density of soil contamination with ¹³⁷Cs in a settlement can be directly used in dosimetric models to estimate the component of the effective dose to a person due to his/her staying in the forest which is located in the area of this settlement. The currently recommended conversion coefficient from the density of soil contamination with ¹³⁷Cs in a settlement to the ambient dose equivalent rate from ¹³⁷Cs in the nearby forest is 1.28 (nSv/h)/(kBq/m² ). To estimate the effective dose from natural radionuclides, it is recommended to use the value of the ambient dose equivalent rate equal to 21 nSv/h.

The article presents the results of a study of the current radiation situation at the uranium legacy site located in the territory of the Bambakai Valley (Transbaikal Territory), formed in the period from 1973 to 1989 due to the discharge of mine water. During the radiation survey, the method of pedestrian gamma survey was used to measure the ambient dose equivalent rate. Soil sampling was carried out to study the radionuclide specific activities in the soil. The activity of gamma-emitting radionuclides in the samples was measured with a stationary gamma spectrometer. The activities of ²¹⁰Po and ²¹⁰Pb were measured after their radiochemical extraction from samples. It was found that the values of ambient dose equivalent rate in the territory of the valley varied over the wide range from 0.1 to 1.4 µSv/h in the areas under manmade contamination. The estimated average value of the gamma background for this place is 0.14±0.02 µSv/h. The specific activities of ²³⁸U, ²²⁶Ra, ²³⁵U, ²¹⁰Pb and ²¹⁰Po in the surface 10-cm soil layer at the site are from 10-40 times higher than the background values. The most part of radionuclides in the soil is in the acid-soluble form. Effective doses of the workers involved in hay harvesting in the area of the fallow land do not exceed 1.5 µSv/year. Doses of terrestrial environmental media (grass, earthworms) are 100 and more times lower than the safe level of exposure to biota.

In radiobiology circulating T-lymphocytes are used as “natural biodosimeters” since the frequency of chromosomal aberrations that occur in them after radiation exposure is proportional to the accumulated dose. In addition, stable chromosomal aberrations (translocations) are detected in them years and decades after radiation exposure. Estimation of doses to circulating lymphocytes requires consideration of two dose components: the dose accumulated by the lymphocyte precursors (progenitors) in the red bone marrow; and dose accumulated by the lymphocytes in the lymphoid organs/tissues during circulation. A recently created model of T-lymphocyte exposure takes into account all these dose components, as well as the age-dependent dynamics of T-lymphocytes. The use of a model approach is especially important in assessing doses from osteotropic beta emitters (^89,90Sr). They accumulate in the bone and locally expose predominately bone marrow. The dose to other lymphoid organs and tissues is much lower. The objective of this study is to evaluate the conversion factors from ingested ^89,90Sr to the cumulative dose to circulating T-lymphocytes and their progenitors (DC_L). For calculations, the previously developed model of T-lymphocyte exposure and new dose coefficients for the red bone marrow, estimated on the basis of a sex-and-age-dependent biokinetic model and a new dosimetric model of the human skeleton were used. As a result, the DCL values were evaluated for the first time. The age at the time of ^89,90Sr intake varied from a newborn to 35 years, the age of T-lymphocyte examination (blood sampling age) was up to 75 years. The maximum values of DC_L for both ⁹⁰Sr and ⁸⁹Sr were typical of children in the first years of life. It has been shown that doses to circulating T-lymphocytes from these radionuclides are lower than those to bone marrow, but are significantly higher than doses to other lymphoid tissues. The effect of sex on DC_L is manifested for children 10 years of age and older. The area of DC_L application covers the population of radioactively contaminated territories (the Urals region, the zone of the Chernobyl accident), as well as personnel of the nuclear industry enterprises.

The aim of the search was to compare the sources of information and evaluate dynamics of changes of the patients doses during x-ray and radionuclide examinations in medical organizations in Moscow from 2017 to 2020. Material and methods: Reporting forms № 3-DOZ, № 30 and Radiation-Hygienic Passport for 2017–2020 from Moscow organizations of different forms of ownership were collected and analyzed. The analysis was performed of the main indicators that determine the radiation safety in medical exposure: the number of medical organizations operating sources of ionizing radiation, the equipment of radiation diagnostics, the structure of radiation diagnostics and collective doses from medical exposure. Results: The analysis of trends of the development of radiation diagnostics in Moscow presented in the paper shows that the number of organizations operating ionizing radiation sources is increasing every year; the number of computed tomography scanners is growing by an average of 10% per year, and there is approximately the same increase in the number of computed tomography examinations. Therefore, in 2017-2019 the annual increase in the number of examinations was 10%; it was 30% in 2019–2020, which is associated with the epidemic of the new coronavirus infection COVID-19. The increase in the collective dose from medical exposure corresponds to the increase in the number of X-ray examinations. Comparison of the considered reporting forms and data from the unified X-ray information system shows that all reporting forms have their advantages and disadvantages, which are discussed in detail in the paper. For a comprehensive assessment of the condition of radiation diagnostics, it is necessary to compile data from different statistical reporting forms, which negatively affects the reliability and representativeness of the data. It should be noted that all the considered statistical reporting forms provide no data on individual and accumulated patients doses, as well as standard (typical) doses for the equipment of X-ray and radionuclide diagnostics. The existing procedure of data collection does not allow to receive and analyze the data online. Conclusion: Among the analyzed statistical reporting forms, there is no one that fully provides the tasks of the current assessment of the situation and operational management of public radiation doses. Some of the data in fact duplicate each other, and the existing discrepancies are more likely express difficulties in collecting and summarizing information than differences in reporting forms. Current statistical reporting forms require revision, consolidation, clarification and automation of data collection processes. Further implementation of electronic systems for recording and controlling patients doses, and generation monitoring and reporting systems, as well as interdepartmental interaction systems and the creation of an electronic office of organizations will reduce the rate of non-submission of reporting documentation. That makes it more objective and provides all the data necessary to optimize radiation protection of patients.

The implementation of targeted medical care to the population of the Republic of Belarus and Russia affected by the Chernobyl disaster is carried out within the framework of national targeted programs, as part of the Union State event «Providing comprehensive medical care to certain categories of citizens of Belarus and Russia exposed to radiation as a result of the Chernobyl disaster» based on medical centers in Russia and Belarus. The relevance of the Measure for the provision of certain types of specialized, including hightech, medical care to citizens of the Republic of Belarus exposed to radiation as a result of the disaster at the Chernobyl nuclear power plant is based on the data on morbidity. The analysis of diseases showed an increase in morbidity rates for such nosological forms as chronic renal failure, secondary and tertiary hypoparathyroidism, diseases of the retina and vitreous body, immunodeficiency states, varicose veins of the lower extremities, acute lymphoblastic leukemia and lymphomas in children. On the territory of the Republic of Belarus in 2016-2021, the provision of comprehensive medical care within the framework of the Measure was carried out at the Republican Scientific and Practical Center for Radiation Medicine and Human Ecology. In 2016-2021, on the base of the Republican Research Centre for Radiation Medicine and Human Ecology 1607 citizens of the Republic of Belarus who suffered from the Chernobyl disaster received high-tech and specialized medical care (in 2016 – 238, in 2017 – 260, in 2018 – 264, in 2019 – 264, in 2020 – 278, in 2021 – 303). The main part of medical care was provided in the surgical applications: transplantation of the kidney and parathyroid glands, surgeries on the posterior segment of the eye, reconstructive surgeries of the pelvic floor in women, laser vein correction. The successful implementation of the Measure in 2016–2021 made it possible to work out the possibility of holding the Measure of the Union State for subsequent years, specifying the amount of funding and additional volumes of comprehensive medical care for citizens in need who were exposed to radiation due to the Chernobyl disaster.

More than half of the Tula oblast territory was contaminated following the accident at the Chernobyl nuclear power plant. This article describes the stages of radiation hygiene monitoring of objects in the habitat in the Tula region impacted by radioactive contamination. Information is given on changes in radioactively contaminated areas at different periods after the accident. An assessment is made of the radiological situation at the initial “iodic” period of the accident, the subsequent “cesium” period, and at the current stage. A description is given of work done by the oblast’s state sanitary and epidemiological service based on radiation monitoring results for reducing the radiation exposure of the population at different stages of supervision. Information is supplied on high levels of gamma background up to 35 mkSv/h during the “iodic” period. Tabulated data are supplied on exceeding the tentative maximum permissible level of iodine-131 content in dairy products produced in Plavski district, the most contaminated area in the region. Data are given on laboratory tests on food products for total beta activity in 1986-87 and the frequency of exceeding the permissible level of cesium-137 content during 1986. The above permissible content of radionuclides in food products was registered only in 1986 due to surface contamination of plants, while in wild mushrooms this took place as late as 2004. Currently, the proved content of cesium-137 and strontium-90 in food products is determined only by the radio-chemical method. A table is supplied showing results of radio-chemical research on major dose contributing food products from 2010 to 2021. The article supplies a table with numeric values of annual average effective doses of radiation sustained by the population of settlements located in the Chernobyl radioactively contaminated zone during 1986 through 2021. The dose of the population’s exposure to the Chernobyl radiation since 1994 does not exceed 1 mSv/year. In 2021, the population’s annual effective dose in 98.3% of settlements amounted to less than 0.2 mSv/year.

More than 36 years have passed since the accident at the Chernobyl nuclear power plant. During these years, a huge number of articles, books, films devoted to this human-made disaster have been published in scientific journals and mass media. The article presents the memoirs of the author – a participant in solving the problems that arose during the liquidation of the consequences of the accident. Specialists of the Institute of Radiation Hygiene worked in the contaminated territories of the Bryansk region, Belarus together with the sanitary and epidemiological service, conducted training seminars for various groups of the public in order to educate and teach the rules of behavior in the current situation. Specialists of the Institute compiled reports on the radiation situation based on data from all sanitary and epidemiological services in the Russian Soviet Federative Socialist Republic on the radioactive state of environmental objects. Based on scientific data, Methodological guidelines and recommendations on the prevention of radiation anxiety, on the work of specialists with medical doctors and other group of population were prepared. Texts of lectures on the effects of radiation on health were written and published in the Znanie society.