This paper continues the series of publications on evaluation of the consequences of the Fukushima-1 nuclear power plant accident and the impact of the emergency radionuclide discharges on the contamination of the sea biota and coastal areas of the Far-East regions. In autumn 2019, the fourth scientific expedition of the Russian geographic society on the monitoring of the radiation situation in Kurily-Kamchatka region was performed on the training vessel «Professor Khlyustin». The expedition included 9 specialists from noncommercial organization «Polar research Fund «Polar Fund», «Russian state hydrometeorological institute», «Radium institute after V.G. Khlopin» of the State Corporation «Rosatom», «Kurchatov institute», «SaintPetersburg research institute of radiation hygiene after prof. P.V. Ramzaev» and «Marine state university after admiral G.I. Nevelsky». The aim of the fourth expedition was to evaluate the radiation situation in the Sea of Japan and Kurily-Kamchatka region after the Fukushima-1 NPP accident as a continuation of the similar marine expeditions in 2011, 2012 and 2014. The survey was performed in the water area of the sea of Japan and Okhotsk sea. The results indicate that the concentration of 137Cs and 90Sr in sea water, hydrobionts, soil, ground and sea vegetation is still on the baseline level due to the global fallouts.

The paper deals with the evaluation of the efficiency of the implemented protective measures in the event of accidental exposure of the Urals region population due to radioactive contamination of the Techa River and the 1957 accident. Both of the accidents occurred in one and the same region within approximately the same time frame, and were caused by discharges of Mayak Production Association radioactive waste into the Techa River (1949–1956) and into the atmosphere (1957). Counter-measures that had been undertaken to provide radiation safety of the population differed both in nature and in timeline. Their efficiency was insufficient in the Techa River basin as they were delayed in time and were not implemented to a full extent. But countermeasures in the East Urals Radioactive Trace were much more effective according to medical and dosimetric criteria. As a result, residents of the Techa riverside settlements received much higher organ doses, including doses to red bone marrow, and health effects of accidental exposure were registered in them both soon after and long after the radiation exposure.

The paper is devoted to comparing the models and the doses of the population external exposure from radioactive fallout after the accident at the Chernobyl and Fukushima-1 NPPs estimated with their help. In the case of the Fukushima-1 accident, the model proposed by the UNSCEAR was used. Both the values of the doses of gamma radiation in the environment and the values of the effective doses of external exposure of comparable population groups normalized to the same surface activity of radionuclides were close for both accidents. The reasons for this are both the similarity of the isotopic compositions of the radioactive fallout and the fact that the “Japanese” model of external exposure was based on the “Chernobyl” model up to using the same numerical values for some parameters, due to the lack of specific Japanese post-accident data for the moment of the first dose estimates for the inhabitants of Japan. For a more accurate comparison of the external exposure of residents after two accidents it is necessary to verify the values of the parameters of the Japanese model using the results of measurements of gamma radiation dose rates in the environment and individual external doses of the residents after the accident at the Fukushima-1 NPP.

The aim of this study was to determine the dynamics of decrease of the dose rate of gamma radiation in air from 137Cs in typical rural locations in the remote period after the Chernobyl accident. The dose rate measurements were performed in the areas of 15 settlements of the Zlynka, Klintsy and Novozybkov districts of the Bryansk region of Russia in the period 1998–2012. After the accident in 1986, the density of contamination of the territory with 137Cs in all settlements was higher than the value of 555 kBq/m2 . Monitoring measurements of the dose rate were performed in eight locations commonly used in assessing the radiation doses to the rural population after the Chernobyl accident: 1) virgin soils (meadows) located outside settlements, 2) virgin soils located inside settlements, 3) forests, 4) arable fields, 5) kitchen gardens, 6) other ground surfaces (earthen yards next to residential buildings), 7) single-story wooden houses, 8) asphalted areas (streets, roads, courtyards next to residential buildings). The number of observation sites in individual locations ranged from 6 to 19 (a total of 103 sites). Series of measurements at individual sites were launched in the period 1998–2001 and completed in 2009–2012. On average, the duration of the series was 11.1 years. The measurements were made in the spring-autumn period annually (in some years at some sites two to three times a year) using a portable gamma-ray spectrometer-dosimeter. In the initial period of the study (1998–2001), the values of the absorbed dose rate in air from 137Cs were in the range from 40 to 2020 nGy/h. The maximum values were recorded in virgin meadows and forests, and the minimum ones were observed inside houses and over asphalted surfaces. By the end of our series of observations (2009–2012), the dose rate decreased at all sites, by an average of 33% (range 6–64%). The values of the ecological period of half-reduction of the dose rate, calculated for individual sites, ranged from 14 to 320 years and averaged 34 years (virgin soils located outside settlements), 30 years (virgin soils located inside settlements), 37 years (forests), 93 years (arable fields), 99 years (kitchen gardens), 33 years (other earth surfaces), 45 years (wooden houses), 60 years (asphalted areas). The deduced values of the rate of decrease of the dose rate of gamma radiation in the air in the surveyed locations were used to estimate the ecological period of the half-reduction of the effective external dose for rural population living in wooden houses. On average, this period was equal to 50 years. Given the radioactive decay of 137Cs, we can expect that the external dose from Chernobyl 137Cs to the rural population will decrease by approximately 4% per year. Our estimate of the rate of decrease of the external effective dose from 137Cs in the remote period after the Chernobyl accident is in agreement with the estimates that were previously given by other authors for the slow component of decreasing external doses from 137Cs to adults living in rural settlements of the Bryansk region.

High levels of tuberculosis morbidity in the Russian Federation lead to the extensive use of X-ray diagnostics for the tuberculosis screening and assessment of the effectiveness of treatment. Digital radiography and computed tomography are traditionally used for the diagnostics of tuberculosis. These methods are associated with significant drawbacks: low specificity for radiography, high costs per examination, significant patient doses, and limited availability for computed tomography. As an additional method for the assessment of the effectiveness of the tuberculosis treatment it is possible to use linear tomography performed on the digital X-ray units. The aim of the current study was to evaluate the possibility of utilization of the digital linear tomography for the control of the effectiveness of tuberculosis treatment in a dedicated antitubercular medical facility. The study was divided in two stages. The first stage was aimed at the assessment of the diagnostic image quality of the digital linear tomograms obtained using the previously developed low-dose imaging protocols. Image quality assessment was performed using an anthropomorphic chest phantom and dedicated imitators of the lung lesions. Image quality was assessed by the experts (radiologists) based on the developed image quality criteria. Results of the first stage of the study indicate that all low-dose protocols allow obtaining images with at least acceptable image quality. Hence it was possible to propose low-dose protocols for clinical evaluations. The second stage of the study was performed as a prospective cohort survey aimed at the evaluation of the structure of X-ray examinations, patient doses and clinical image quality of the digital linear tomograms in antitubercular early treatment center. The cohort survey included two patient samples, uniform by age and gender composition, anthropometric characteristics and structure of diagnosis. One of the samples was imaged using standard (vendor) digital linear protocols, other – using the proposed low-dose protocols. Dose data collection (measurement of dose-area product and subsequent calculation of effective dose) and expert image quality assessment was performed for each patient. The results of the second stage of the study indicate that the use of the low-dose protocols allow reducing the patient effective doses per examination up to a factor of 6–8 (0.56 – 5.9 mSv for standard protocols; 0.2 – 1.15 mSv for low-dose protocols) due to the reduction in tube current-time product (126 mean mAs and 11 mean mAs, respectively). The dose reduction is accompanied by the reduction in the image quality of the linear tomograms (from “excellent” or “good” for standard protocols to “acceptable” for low-dose protocols). However, that dose not hinder the conclusion decision and identification of pathologies. Results of the study indicate that digital linear tomography can be used for the evaluation of the dynamics of the pathological process in the lungs with the previously defined localization of the pathology. The presented low-dose protocols were implemented into radiological practice of the antitubercular early treatment center. Currently, the proposed low-dose protocols are under evaluation for the large-scale study on the base of general practice hospitals

The purpose of the work was to study the ability of the NOS inhibitor T1023 to prevent late radiation injuries. Methods: the effects of T1023 (75 mg / kg, once i.p. 30 minutes before the irradiation) on the development of post-radiation pulmonitis and pneumofibrosis in rats with thoracic exposure to g-radiation at  a dose of 12.5 Gy were studied histopathologically and morphometrically. The results of the studies showed that there wasn’t a significant objective effect of T1023 on the development of early radiation-induced lung injuries  (9 weeks after irradiation). But it prevented late radiation induced lung injuaries (26 weeks after irradiation) – there were a significant lesser pathomorphological manifestations of post-radiation pulmonitis, proliferation of connective tissue and the development of fibrotic changes in the lung parenchyma. At this stage, the action of T1023 clearly contributed to the preservation of the normal histostructure of the lungs, reducing by 40% the content of compaction zones in the parenchyma. The ability of the NOS inhibitor T1023 to significantly limit the development of lungs late radiation reaction confirms the promise of further development  of this compound as a means for prevention radiation therapy complications.

The article presents the results of radon monitoring on the territory of Northern Tajikistan. Analysis of the results of the monitoring shows that at present, relatively high values of radon concentration in the atmospheric air are found in the areas where uranium tailings are located, primarily in the city of Istiklol and the Dehmoy tailings dam. This is primarily due to the lack of protective coatings on the surface of the tail material, which turns this area, in fact, into radon-prone areas of technogenic origin. In different parts of the Dehmoy tailings dam, the radon concentration in the atmospheric air varies between 200 and 1000 Bq/m3, and the radon flux density from the surface reaches 65,000 mBq/(m2∙s). On the territory of tailings dam in the city of Istiklol, the value of radon concentration in the atmospheric air is in the range of 44–195 Bq/m3. At the same time, it was found that the radon potential of the tailings dams, where the surface has a protective coating, is much lower. For example, the radon flux density from the surface of the Gafurov tailings dam, where surface is covered with loess-like loams up to 2.5–3.0 m thick, does not exceed 100 mBq/(m2∙s), with average values of 40-60 mBq/(m2∙s); the radon concentration in the atmospheric air is about 55 Bq/m3. Despite the intense exhalation of radon from the surface of some tailings dams, their territory is not currently a residential zone and, accordingly, does not affect the radon situation in buildings located in the settlements nearby. In the cities of Khujand, Buston, Gafurov, Istiklol and the village of Adrasman, the average values of indoor radon concentration do not exceed maximum permissible levels. It is recommended to conduct a full rehabilitation of uranium legacy sites, primarily uranium tailings dams in the city of Istiklol and Dehmoy tailings dam, for the improvement of the radon situation in Northern Tajikistan with consideration for possible expansion of the settlements.

The article provides a brief description of organizational and technical measures aimed at ensuring radiation safety during the decommissioning of the heavy-water research nuclear reactor of Institute for Theoretical and Experimental Physics after A.I. Alikhanov of National Research Centre «Kurchatov Institute». Information is provided on the history and features of the operation of the reactor, including parameters and characteristics that are significant for planning and conducting work. The peculiarities of legal regulation in the field of ensuring radiation safety are given; regulatory acts and rules accompanying other activities during decommissioning and directly related to radiation safety are also considered. The paper describes the work done in preparation for dismantling, the initial and current state of the installation, forthcoming work with examples of dismantled equipment. Methods for handling radioactive waste arising during decommissioning are considered, including methods for fragmentation of large structural elements (examples of mechanical devices are given), methods for sorting according to different specific activity (high activity, low activity), radionuclide composition and physical properties (solid, metallic, non-metallic, liquid). A special method for handling liquid radioactive waste is described, which includes the collection and temporary storage system. To assess the radiation situation at workplaces during the dismantling of the reactor structures, calculations of radiation transfer were carried out on the running and shutdown reactor, during which it was established that the expected dose to the personnel when performing activities on decommissioning of TBR is much lower than the limit values, established by regulatory documents. In accordance with the estimated radiation doses, rules and instructions for personnel were determined, including the procedure for using personal protective equipment, the necessary measures for surface decontamination, etc. Information is given on the procedure for radiation monitoring at all stages of dismantling and at the final stages of decommissioning including control of premises, personnel, equipment, waste of various types, atmospheric air.

The article provides brief information about the life and working activities of the first head of the Department of Radiation Hygiene of the Central Institute for Advanced Medical Training, academician, Doctor of Medical Sciences, Professor, Major General of the medical service F. G. Krotkov in the field of military hygiene during its formation in the Soviet health care, in the pre-war years and during the great Patriotic War. The direction of the scientific work of F. G. Krotkov at the Department of hygiene of the Military Medical Academy and contribution to the basis of the Aviation Scientific Research Institute of Sanitary in the WorkerPeasant Red Army and the Special Food Research Institute of the Red Army and its role in improving the combat capability of the Army and Navy as the head of the sanitary Department of the Main military-sanitary Directorate of the Red Army. It also reflects the activities of Professor F. G. Krotkov on the development of radiation hygiene as the head of the country’s first specialized Department in the Central Institute for Advanced Medical Training. The paper provides information on perpetuate the name of Professor Krotkov on his small Home in S. Mosolovo, the Ryazan oblast and in Moscow city, where he worked for many years.

The object of the study is the cohort of individuals exposed in the Southern Urals in the 1950s at the age of 0–19 years. The relevance of the creation of the cohort of individuals exposed in childhood and adolescence is determined by their high sensitivity to radiation exposure and is associated with the need for differentiated assessments of the radiation risk of morbidity and mortality for individuals exposed at different stages of ontogenesis. The work includes definition of the cohort, the criteria for inclusion and exclusion from the cohort. According to the data as of 01.01.2019, the created cohort includes 32,461 potential members exposed as a result of living in the riverside villages of the Techa River and on the territory of the East Ural radioactive trace; the follow-up period of the cohort is 70 years (from 1950 to 2019). The cohort has an almost equal number of men and women, includes two ethnic groups (Slavs and Turks), the age range is from 0 to 91 years. The formed cohort can be used to assess the radiogenic risk of cancer and non-cancer morbidity and mortality for the low and medium doses of exposure

Peculiarity of various methodology aspects for estimate radiation risk in dependence of using area are discussed in this article; perspective of the estimate perfection is discussed too. It is consideration such area of using as medico-biology, epidemiology, radiation protection, medical exposure. The opinion expressed that it is difficult to insert subjectively-psychological perception of risk in the methodology. It is generalized systematically author’s methodological judgement, which been published before. The article contain discussion moment, which is inevitable in given theme.

This article presents the review on the monograph “Scientific bases of radiation protection in modern medicine “volume 1” X-ray diagnostics “ by M.I. Balonov, V.Yu. Golikov, A.V. Vodovatov, L.A. Chipiga, I.A. Zvonova, S.A. Kalnitsky, S.S. Sarycheva, I.G. Shatsky, edited by Professor M.I. Balonov. – St.-Petersburg Institute of Radiation Hygiene after prof. P.V. Ramzaev, 2019. Due to the increasing use of ionizing radiation in medicine, implementation of new imaging modalities and equipment, increase of the patient and staff doses, the aspects of their radiation protection are very relevant. The monograph is based on the analysis of data from national and foreign studies, as well as the data from own research conducted in the laboratory of radiation hygiene of medical facilities of the St. Petersburg Research Institute of Radiation Hygiene named after Professor P. V. Ramzayev for almost 20 years. It reflects the current trends in radiation protection for various imaging modalities and it will be useful to a wide range of readers, especially specialists in the field of X-ray diagnostics and radiation hygiene.