Development of the automated system for assessing radiation risks to the population of the Russian Federation based on the data of radiation-hygienic certification of territories

The assessment of the radiation risk based on the data of the radiation-hygienic passports of the territories makes it possible to give a brief quantitative characteristic of the negative impact of sources of ionizing radiation on the health of the population of various regions of the Russian Federation at the population level. The calculation of individual indicators of radiation risk for the population of particular region of the Russian Federation is a time-consuming task that requires referring to radiation-hygienic passports of territories for particular years. Therefore, the purpose of the performed work was to develop specialized software designed to assess the indicators of radiation risk to the population of the Russian Federation according to the data of the radiation-hygienic certification system of territories. Automation of the calculation of radiation risk allows not only to simplify the calculation procedure but also to carry out a spatial-temporal analysis of risk in dynamics for different regions of the Russian Federation over long periods. The methodological basis for the software development is guideline MR 2.6.1.0145-19 “Calculation of radiation risk according to the data contained in the radiation-hygienic passports of the territories to provide a comprehensive comparative assessment of the radiation safety status of the population of the subjects of the Russian Federation”. To achieve the set goal, two computer programs were developed: 1) to automate the process of calculating radiation risk based on the information contained in the radiation-hygienic passports of territories, a computer program “Calculation of radiation risk indicators according to RGPT data”; 2) for the spatial visualization of the calculations, a specialized geographic information system “Radiation risks of the population of the Russian Federation according to radiation-hygienic certification data”. The computer programs developed in the course of the work allow an automated calculation of radiation risk based on the data of radiation-hygienic passports of territories, visualize the spatially distributed results of calculating radiation risk, carry out a preliminary assessment of the state of radiation safety, based on the data contained in radiation-hygienic passports of territories using radiation risk indicators.

Radiation doses to the population of the Russian Federation in 2020

The article presents estimates of radiation doses of technogenic exposure to personnel and the public due to the normal operation of radiation facilities, exposure to the public due to natural sources and technogenically altered radiation environment, and medical exposure of patients. The doses values were obtained using the Unified System of Individual Dose Control of the Russian Federation citizens for 2020. The authors have analyzed the data contained in the forms of state statistical observation No. 1-DOZ, No. 2-DOZ, No. 3-DOZ and No. 4-DOZ for 2020 submitted by the organizations and territories, the state sanitary and epidemiological supervision of which was carried out by Rospotrebnadzor and Federal Medical Biological Agency of Russia. In the article also were used data obtained within the framework of Radiation-Hygiene Passportization. In 2020, 19 737 organizations dealing with technogenic sources of ionizing radiation submitted forms No. 1-DOZ with the information on the doses to personnel with a total number of 230 318 persons, of which 230 318 persons belonged to the personnel group A and 21 303 persons belonged to the personnel group B. For these groups, the doses were assessed based on results of individual dosimetric control. In 2020, according to Unified System of Individual Dose Control of the Russian Federation citizens data, the average individual annual effective dose of technogenic exposure to the personnel group A was 1.11 mSv, and for the personnel group B it was 0.63 mSv. In 2020, 6 cases of exceeding the average annual effective dose limit (20 mSv) for Group A personnel and 18 cases of exceeding the average annual effective dose limit (5 mSv) for Group B personnel were registered. The total number of X-ray and radiological diagnostic procedures performed in the Russian Federation in 2020 exceeded 275.4 million, or 1.83 procedures per a citizen. The average annual effective dose of medical radiation exposure per one resident of Russia in 2020 was 0.81 mSv, and per procedure – 0.44 mSv. The average annual effective dose of radiation to residents of the Russian Federation from natural sources, according to all measurements for the period from 2001 to 2020, was 3.36 mSv. More than 59% of this dose is associated with the inhalation of radon and its progenies. The average individual annual effective radiation dose to residents the Russian Federation subjects in 2020 ranged from 2.47 mSv (Kamchatka Krai) to 9.06 mSv (Altai Republic) with an average value for the Russian Federation of 4.18 mSv. For eight subjects of the Russian Federation, the average individual annual effective dose to public in 2020 exceeded 5 mSv: the Republics of Buryatia (5.31 mSv), Altai (9.06 mSv), Tyva (6.31 mSv), Magadan (5.07 mSv) and Irkutsk (6.13 mSv) regions, Stavropol (6.31 mSv) and Zabaykalsky (8.19 mSv) krai and the Evreiskaya Autonomous oblast (6.77 mSv).

Consideration of the contribution of the natural background component during individual control of radiation doses to personnel

When ensuring radiation safety in the Russian Federation, there is a principle of separate independent assessment of doses from natural, medical, emergency and technogenic exposure. In practice, it is not always possible to comply with this principled approach. The established dose limits are related only to man-made radiation during normal operation of sources of ionizing radiation. However, during the formation of regional and federal databases on individual doses of personnel exposure, information is entered not on technogenic exposure, but on industrial exposure, that is, without subtracting the natural radiation background. The natural component of the individual dose at low radiation doses is quite significant. Failure to its subtraction leads to an overestimation of the individual dose of external exposure of personnel. Difficulties arise in the implementation of the subtraction of the natural radiation background: 1) in what cases it is necessary to subtract the background, 2) what value to choose for the subtracted background, 3) what method to measure the background, 4) at what stage of processing the measurement information to subtract the background. This article proposes a method for solving the problem of subtracting the natural background radiation from the values of individual doses of external exposure to personnel based on results of individual dosimetric control. Using the example of the city of St. Petersburg, the natural background radiation was measured by the thermoluminescent method of individual dosimetry at 50 control points for three consecutive years (2018-2020). To measure the natural background, we used individual thermoluminescent dosimeters of the same type as those used to measure individual equivalents of external radiation doses to personnel. The choice of using the thermoluminescent method as a predominant one for adjusting the average doses of external radiation from technogenic sources of ionizing radiation when subtracting the natural component of the dose has been substantiated. Comparison of official data on personnel exposure doses with the data obtained as a result of our own measurements is made. Recommendations are given on the use of the obtained values of the average natural radiation background in the formation of regional and federal databases on individual doses of personnel exposure.

Universal calibration of a scintillation spectrometer with a NaI(Tl) detector when measuring 137Cs activity in counting samples of arbitrary density and volume

The article proposes an empirical method for constructing a universal calibration for a scintillation gamma spectrometer, which allows determining the activity and specific activity of 137Cs with an accuracy of no more than 15% in counting samples of arbitrary density and volume in cylindrical containers with a volume of 250 ml and 500 ml. To construct calibration ratios, measurements of 137Cs sample media prepared on the basis of materials of different densities (quartz sand, plastic granules and sawdust) were performed. The calibration was carried out by preparing samples from the listed materials with a volume of 50 to 250 ml in increments of 50 ml for a 250 ml container and 100-500 ml in increments of 100 ml for a 500 ml container. Along with taking into account the volume of the counting sample, its weighing was also carried out. The result of the measurements performed for each material was the ratio of the activity of the counting sample to the counting intensity in the 137Cs window, depending on the volume. The universal calibration factor is obtained by taking into account the counting rate from the mass and volume of the sample for the corresponding measuring vessel.

On the 125th anniversary of the discovery of radioactivity: history of development and current state of regulation of the provision of the radiation safety of the public

This paper is focused on the history of development and current state of regulation of the provision of radiation safety of the public. It includes data on the history of discovery of the X-rays, radioactivity and development of the atomic industry in the USSR and in the world as well as the issues of evaluation of the radiobiological effects of the ionizing radiation on the human and history of the development of regulations. It is indicated, that the principles of the radiation safety, norms and approaches to the provision of the radiation protection presented in the Federal state Law № 3-FZ “On the radiation safety of the public” and NRB 99/2009 fully comply with the ICRP Publication 60 (1990) and International Basic Safety Standard (IAEA, 1997). For decades, FZ-3 and NRB 99/2009 have allowed provisioning the high level of radiation safety of the personnel and the public.

241Am and 137Сs in the Khoiniki district of Belarus: updated radiological assessment of the local existing exposure situation

The results covered in this paper relate to the “Khoiniki” research sub-unit of a larger-scale sequence of studies focused on the local assessments of the present-day 241Am and 137Cs concentrations in the soils and locally produced foods, with the estimation of the public internal radiation doses in the residential areas of the Gomel region of the Republic of Belarus most closely adjacent to the ChNPP resettlement zone. The objective was to make a conservative estimate of a committed annual dose of internal exposure from 241Am and 137Сs received by the villagers of 96 farmsteads in 30 settlements of the private sector of Khoiniki countryside through both, inhalation and consumption of local foodstuffs. The results obtained in this study include an update of the existing contamination levels of 241Am and 137Сs present in the local soils and foods grown or produced in private backyards and households. 241Am in food samples was determined by alpha-spectroscopy radiochemical analysis with the use of selective extraction-chromatographic resins. Gamma-spectrometry techniques were used to measure 241Am in soil samples and 137Сs in soil and food samples. Based on our findings, the present-day deposition density of 241Am in the soils does not exceed 4 kBq/m2 , while the values of 137Cs contamination are by one to two orders of magnitude higher than that of 241Am and vary between 30 and 500 kBq/m2 . Generally, the values of activity concentration of 241Am detected in local soils are well within 10 Bq/kg in the majority of inspected villages, with the exception of three sites where higher levels of 241Am contamination is soils were detected ranging from 14 to 16 Bq/kg. The ambient dose rates in the countryside range from 0.05 to 0.38 μSv/hour, with the average of 0.15 μSv/hour. No cases of 137Сs contamination above the established reference levels of 80, 100 and 90 Bq/ kg have been found in the local food samples of, respectively, potatoes, vegetables (incl. roots and tubers) and grains. The content of 241Am in the staple foods produced in the area varies from single digits to tenths of mBq/ kg, which is less by three orders of magnitude than 137Сs activities concentrationd found in the same staples. Of the two pathways contributing to the local committed internal exposure from 241Am, the dominant one is through inhalation (0.006–0.038 mSv/year) prevailing over the consumption pathway of this same radioisotope by at least one order of magnitude. At the time of gardening and other household field works, the existing levels of 241Am contamination in soils are estimated to produce from 85 to 98% of the internal radiation dose received by individuals from inhaling the total of 241Am and 137Сs. The maximum committed annual doses of internal exposure from 137Сs are estimated to be above 1 mSv/year in 6 out of 30 villages engaged in our study. At the same time, the estimated internal radiation dose due to 241Am does not surpass 0.04 mSv/year. The 137Сs major contribution to the internal exposure of villages in the Khoiniki countryside is through food consumption.

Comparison of early forecasts of the incidence of thyroid cancer in residents of the Russian Federation after the Chernobyl accident with observational data

A review of methods for assessing doses in the thyroid gland, predictions of the long-term consequences of its irradiation and the actual incidence of thyroid cancer in residents of four regions of the Russian Federation with the most significant radioactive fallout after the Chernobyl accident are presented. The method for assessing doses in the thyroid gland is based on the results of monitoring in May-June 1986 of radioiodine in the environment, food and in the body of residents. Thyroid doses in the population were used to justify medical and social protection measures, as well as epidemiological studies. In addition, the authorities needed forecasts of the possible morbidity of the population in order to organize adequate medical care. Most of the thyroid cancer cases were predicted among the adult population, which was not confirmed by observations 35 years after the accident. The prognosis of the incidence of thyroid cancer in preschool children differed in different studies due to the use of different coefficients of reducing the biological effectiveness of 131I radiation in the thyroid gland and long-term external and internal irradiation of the whole body with a low dose rate compared to the effect of acute exposure. The increase in the incidence of thyroid cancer among children began five years after the accident at the Chernobyl nuclear power plant. Examples of the dynamics of the incidence for children in the Bryansk region of the Russian Federation are given. The 2018 UNSCEAR Report showed that for 1986-2015, among children and adolescents under 18 years of age on the day of the accident in Belarus, Ukraine and four regions of Russia, more than 19 thousand thyroid cancer cases were detected, of which the share of radiation-induced diseases was estimated at 25%. For four regions of Russia, this amounts to 460 cases with a range of possible estimates from 130 to 900 cases. The highest morbidity was manifested among younger children exposed at the age of 0-4 years. In older children and adolescents, the proportion of radiation-induced diseases has significantly decreased 30 years after the accident. In general, early forecasts of radiation-induced thyroid cancer incidence in children in four regions of the Russian Federation with high levels of radioactive fallout are consistent with the data of subsequent 30-year epidemiological observations within an order of magnitude. With regard to thyroid cancer in adults, such a comparison is difficult, since no radiogenic increase in the incidence has been detected.

Ambient dose equivalent rate and soil contamination density with 137Cs in kitchen gardens in settlements of the Bryansk region, Russia in 2020–2021

The article provides results of application of the field (in situ) gamma spectrometry method for carrying out mass monitoring measurements of ambient dose equivalent rate and soil contamination density with 137Cs in kitchen garden plots located in the zone of radioactive contamination after the Chernobyl accident. In 2020 and 2021, 115 private farmsteads in 46 settlements of the Bryansk region were surveyed. At the time of the survey, the officially established average density of soil contamination with 137Cs in the settlements ranged from 27 to 533 kBq/m2 . The field spectra were measured using a portable scintillation gamma-spectrometer-dosimeter. Results of the field measurements and subsequent calculations of soil contamination density with 137Cs in the kitchen gardens were in good agreement with official data on the average soil contamination density with 137Cs in the surveyed settlements. The mean value of the ratio of the experimental data to the official data was 1.04. Individual values of experimental data deviated from corresponding official values by no more than two times. The use of the gamma spectrometry method in situ made it possible: 1) to determine separately values of the ambient dose equivalent rate from 137Cs and from natural radionuclides in the soil, and 2) to estimate the effective external doses to a person who worked in the kitchen gardens. The measured values of ambient dose equivalent rate varied from 17 to 53 nSv/h (mean ± standard deviation = 35 ± 9 nSv/h) for natural radionuclides and from 8 to 432 nSv/h (mean ± standard deviation = 125 ± 91 nSv/h) for 137Cs. The ambient dose equivalent rate from 137Cs normalized to the soil contamination density with 137Cs in the same kitchen garden was in the range of 0.41–0.84 (nSv/h)/(kBq/m2 ) with a mean value of 0.55 (nSv/h)/(kBq/m2 ). If a person stayed in kitchen garden for 840 hours per year, the estimated effective external doses from natural radionuclides and 137Cs were respectively in the range of 0.008–0.025 mSv/year and 0.004–0.20 mSv/year.

Analysis of patient medical exposure in X-ray diagnostics in Russia for half a century (1970–2019)

During last 50 years, firstly in the RSFSR in the USSR (1970-80), then in the Russian Federation - RF (1990-2019), the authors studied the radiation safety issues of patients from medical exposure. The reader is offered a complex radiation-hygienic analysis of the 50-year medical exposure of patients and of the population in Russia to inform and analyze the available data on the most common type of use of ionizing radiation sources in the national economy. For a half century, several generations of people have changed and medical diagnostic X-ray equipment and technologies have also radically changed. The information from this article was obtained on the basis of radiation-hygienic statistics, as well as considered our research. The data is presented at the federal level in the form of the volume of research carried out- determined by the number of X-ray procedures, as well as the level of medical exposure in the form of effective dose of patients in Russia - a huge region with a population of about 150 million people, where about 200 million X-Ray procedures were performed annually, i.e. about 10 billion X-Ray procedures for the entire observation period. During the study, a collective effective dose was - 6.5 million person-Sv at the rate of 100 thousand person-Sv and more per year. The paper presents the dynamics and the structure of the studied indicators depending on the type of medical exposure, as well as its localization. The contribution of the X-ray diagnostics to the total volume of radiation diagnostics, which is developing dynamically, is presented. It was found that throughout the study, there were two oppositely directed processes: an increase in the number of X-Ray procedures and a decrease in the effective doses of patients. At present, the minimum dose has been reached, after that it has been increasing began, associated with the use of new computer technologies. It was determined that, depending on the localization, the main radiation load during X-ray procedures falls on the skeleton and digestive organs. It is shown that during the study period (in 1986) there was an accident at the Chernobyl, which significantly affected on medical activities and, in particular, X-ray diagnostic indicators. The paper shows the consequences of these situations. In general, the data presented is huge in volume and significant in information content. The information obtained on the basis of such a unique data is representative and allows, firstly, to analytically study the issues of radiation protection of patients and, secondly, to plan the strategy and tactics of its development.

Features of radiation protection equipment for the staff of X-ray operating rooms

This survey is devoted to the staff radiation protection in X-ray operating rooms. For self-safety staff must regularly and correctly use the protective equipment, which is ensured by their availability, convenience and manoeuvrability during procedures performing. The rapid development of interventional radiology led to the fact that the staff work in this area have one of the highest levels of occupational exposure. Unfortunately, domestic radiation protection system does not keep pace with such a rapid development of this branch of medicine. The article shows the basic principles of the distribution of scattered radiation in the X-ray operating room during the procedures performing. The distribution of scattered radiation around the patient for various modes of C-arm angiographic systems is shown. Graphical examples of scattered radiation distribution in X-ray operating rooms are given. Collective and individual protective equipment specifically designed for staff radiation protection in X-ray operating room are considered in detail. The common data on the protection features of the recommended staff protection equipment are presented. Most of the considered protection equipment is mandatory in many European countries, but not mentioned in domestic regulatory documents yet. The proposals for the modernization of the domestic radiation protection system for staff of X-ray operating rooms have been made. These recommendations focused on providing X-ray operating rooms with relevant radiation protection equipment, including eye protection, following the accumulated world experience and international regulations.