Implementation of modern highly informative methods of X-ray diagnostics (computed tomography, interventional examinations, nuclear medicine), associated with the increase of doses to the public and patients, requires the development and improvement of the existing system of the radiation protection from medical exposure. Despite the prevalence of the traditional imaging modalities in the structure of X-ray diagnostics in the Russian Federation (radiography and fluorography compose up to 95% out of 280 mln. X-ray examinations performed in 2017), the major contribution into the collective dose from medical exposure is due to the computed tomography (50,5%). Comparison of the structure of X-ray diagnostics in the Russian Federation with European Union indicates the absence of fluorography examinations and significantly (up to a factor of 5) higher contribution of computed tomography in European countries. An average collective dose from medical exposure in European countries is composed of 80% of computed tomography and of 10% of nuclear medicine; a mean effective dose per X-ray examination are higher up to a factor of 3 compared to Russia. The analysis of the trends of the development of the X-ray diagnostic in the Russian Federation allows predicting a further increase of the number of computer tomography, interventional and nuclear medicine examinations as well as an increase of the collective dose from medical exposure up to a factor of two in the  next decade. This will be associated with changes in the structure of the X-ray diagnostics and an increase of the mean effective doses from X-ray examinations.

The aim of this study was to analyze the current radioecological situation in agriculture in five south-west districts of the Bryansk region, which were exposed to the most radiation influence due to the accident at the Chernobyl NPP. Currently, there are 135 collective farms in the observed areas. The total area of agricultural lands was 266.2 thousand hectares. The area of agricultural lands with 137Cs contamination over 37 kBq/m2 was 244.8 thousand hectares in 2018. The area of arable land, hay fields and pastures located in the zone with a 137Cs soil surface activity in a range of 37–185 kBq/m2 is 135.1 thousand hectares, 185–555 kBq/m2– 88.3 thousand hectares, 555-1480 kBq/m2 – 19.8 thousand hectares. At present, only 21.4 thousand hectares (8% of the agricultural lands in the considered areas) don’t exceed contamination levels of 137Cs 37 kBq/m2, and they can be classified as “clean territory”. Analysis of the agricultural products radiation monitoring data from the collective farms of the south-west districts of the Bryansk region showed that the part of feed and crop products exceeded the standards varied from 4 to 15% in 2017-2018. The high content of 137Сs in the feed of several collective farms determined the excess of sanitary and hygienic standards in livestock products from these farms – milk in 4-8% of total samples, beef in 5–8% of total samples. The collective farms located in Krasnogorsky and Novozybkovsky districts of the Bryansk region, with a high risk of exceeding the standards for the content of radionuclides in the agricultural products, was identified. The required volumes of rehabilitation measures in the plant growing and animal husbandry of the south-west districts of the Bryansk region was indicated. It was found that 75 thousand hectares of the total area of agricultural lands need radical improvement and the introduction of higher doses of agromeliorants to produce plant-growing and fodder products corresponding to the legislation standards. To produce milk and beef that comply with sanitary and hygienic standards for livestock products, it is necessary to use ferrocyanide treatment in volumes of 10.5 t/a. It was shown that most radioactively contaminated rural areas need individual programs for the application of rehabilitation technologies. Such programs should provide the population safety and domestic activity. 

Previous studies conducted by the Federal Service for Surveillance on Consumer Rights Protection and Human Well-Being (Rospotrebnadzor) in Sakhalin Region, Russia in 2011–2012 have shown that soils on the southern Kuril Islands were contaminated with 137Cs and 134Cs due to the accident at the Fukushima-1 NPP. In this study, we evaluated the air kerma rate from 137Cs and 134Cs using earlier published data on the vertical distribution of Fukushima-derived radiocaesium in the soil at grasslands on the islands of Kunashir, Shikotan and Iturup. The air kerma rate due to gamma-rays from pre-Fukushima 137Cs was estimated as well. In the period from May 2011 to September 2012, the air kerma rate due to the fresh fallout of radioactive caesium varied from 0.31 to 0.84 nGy h−1. On average, the contribution of the radiation from Fukushima-derived 134Cs and 137Cs to the total air kerma rate from radioactive cesium was 35% in the fall of 2011 and 25% in the fall of 2012. The mean normalized kerma rate from Fukushima-derived 137Cs was estimated at a level of 1.63 nGy h−1 per kBq m−2 in mid-May 2011, 1.53 nGy h−1 per kBq m−2 in autumn 2011 and 1.45 nGy h−1 per kBq m−2 in autumn 2012. The mean normalized air kerma rate from pre-Fukushima 137Cs at reference undisturbed grasslands was estimated as 0.77 nGy h−1 per kBq m−2. The results of our calculations of the air kerma rate from Fukushima-derived 137Cs were in good agreement with the forecast of the 2013 UNSCEAR model, which was used to estimate the external doses of the Japanese population after the Fukushima accident. For pre-Fukushima 137Cs, the UNSCEAR model underestimated the calculated normalized air kerma rates in Sakhalin Region by approximately 40%. Our calculations showed that, overall, the aboveground biomass of herbaceous plants had practically no effect on the air kerma rate from radioactive cesium contained in the soil. The fallout of 134Cs and 137Cs after the accident at the Fukushima-1 NPP did not lead to any significant increase in the gamma dose rate in the air at grasslands on Kuril Islands. In 2019–2020, the contribution of radiocaesium to the total gamma dose rate in air will not exceed 5%. 

The paper describes for the first time the results of the radiation effect study using the example of the analysis of circulatory system disease mortality in newly established cohort combining the population exposed in 1950–1960 due to 2 radiation incidents in the Southern Urals (the Techa River and East-Urals radioactive Trace). The cohort consists of 60,205 people. Over a 65-year follow up period 14,830 deaths from all diseases of the circulatory system were registered. Out of this number 6,163 deaths were from ischemic heart disease, and 4,388 deaths were from cerebrovascular diseases. Analysis was performed on the basis of individualized estimates of dose accumulated in muscle tissue (both internal and external components of the dose), calculated with new Techa River Dosimetry System 2016. As per the latest calculations, mean dose to muscle tissue in members of the combined cohort was 34 mGy, maximum dose was 995 mGy. Simple parametric model of excess relative risk (ERR) was used in the analysis. The number of person-years at risk was 1836,203. The findings of the analysis show linear increase of mortality risk per unit dose from all the disease of circulatory system (ERR/100 mGy was 3%; 95% CI: 0,8%; 5,2%) and from ischemic heart disease (ERR/100 mGy was 9,2%; 95% CI: 5,4%; 13,5%). with 15-year latent period. No statistically significant increase in mortality from the cerebrovascular diseases in the combined cohort of the population exposed in the Southern Urals over a 65-year period received evidence. The obtained results are in good agreement with those received in the analysis of the effect in the Techa River Cohort in 2013. The latter covered a 53-year period (with minimum latent period of 15 years) and revealed statistically significant linear dose response for all diseases of the circulatory system (ERR/100 mGy – 0.036) and ischemic heart disease (ERR/100 mGy – 0.056).

Assessment of the quality of the images obtained using optimized (low-dose) protocols is the inherent part of the optimization in X-ray diagnostics. To perform the objective quantitative image quality assessment one can use dedicated test-objects, including several components for the simultaneous measurement of the different physical image characteristics (contrast and spatial resolution). The use of such test objects allows estimating and assessing the relations between the patient dose, parameter of the X-ray examination and image quality. That is especially important for the optimization of the digital radiographic examinations performed with automated exposure control. The aim of the current study was to evaluate the possibilities of the patient dose reduction using “contrast-detail” test-object for the digital radiography of the chest in posterior-anterior projection performed with automated exposure control. The study was performed in St-Petersburg Mariinsky hospital on a digital X-ray unit “ARC-Electron” with a flat-panel detector. The combination of a test-object and a tissue-equivalent phantom were imaged on a range of chest X-ray protocols: on a 60–150 kV tube voltage range with automated exposure control; and using fixed 90 kV tube voltage on a range of 2–100 mAs tube current-exposure time product. Dose-area product (cGy×cm2) was measured for each exposure; effective dose (mSv) was estimated for each exposure based on dose-area product. A dedicated software was developed for the automated image quality assessment. The results of the study indicate that the use of a high tube voltage (140–150 kV) with current automated exposure control settings would lead to 60% and 95% reduction of the dose-area product and effective dose, respectively, compared to the standard protocol. The adjustment of the current automated exposure control settings with the reduction of the tube current-exposure time product from 11,2 mAs to the 4,2 mAs for the tube voltage of 90 kV would lead to the reduction of both the dose-area product and effective dose up to a factor of three, compared to the standard protocol. For both scenarios image quality characteristics decreased by less than 15%. The proposed low-dose protocols are under the clinical approbation at Mariinsky hospital. The proposed method of image quality assessment and development of low-dose protocols is recommended for inclusion in the quality assurance program for the radiography examinations.

The aim of the study was to justify and develop a model of risk communication with the public on radiation protection issues and to conduct research based on it in St. Petersburg and the Leningrad Region. The proposed model of risk communication consists of five continuously and cyclically alternating each other stages: 1) scientific research; 2) a scientifically based system of practical measures; 3) a regional risk communication program on the radiation protection of the public; 4) practical arrangements for the implementation of the program; 5) research to assess the effectiveness of risk communication. Four sets of questions to be answered in the framework of scientific research were identified: 1) the characteristics of the radiation-hygienic environment; 2) the demographic situation and the state of health of the public; 3) attitudes of the participants of the risk information field; 4) information field characteristic. The results obtained through the  research allowed substantiating the system of practical measures: 1) to determine the directions of risk communication, 2) to assess the need for developing local programs within the framework of regional ones; 3) to assess the level of knowledge and perceptions of the public about possible sources of radiation risk; 4) to identify stakeholders in risk communication; 5) to determine the types and list of information materials and information resources that are optimal for different groups of stakeholders. The conducted studies indicate that the radiation situation in St. Petersburg and the Leningrad Region is stable. These regions contain all exposure situations that require the development of local risk communication programs. p Several differences were revealed in health indicators of the public in St-Petersburg and the Leningrad region. Public knowledge on radiation protection issues can be characterized as fragmented and uncertain. The preferred source of information for the public is the Internet. Among all sources of information, unconditional leaders in the level of public confidence are the employees of the Ministry of Emergency Situations, scientists and specialists. More than half of the respondents in St-Petersburg and the Leningrad Region (73% and 60% respectively) had no  information about key public organizations covering issues of the radiation protection of the public, which indicates a rather low effectiveness of the activity of these public organizations. Both in all and in certain categories of mass media, a significant part (more than 50%) are publications with a neutral presentation of information. Only the media of the city of Sosnovy Bor is characterized by the active involvement of specialists in the radiation safety of the public in the preparation of information materials. 

During 2001–2017 more than 800 thousand records containing the results of measurements of radon concentration taken in 78 regions of Russia were accumulated in the Federal databank of radiation doses to the population of the Russian Federation. The paper presents the procedure and results of the first data analysis carried out to check the conformity of radon concentrations in the regions of Russia with the lognormal distribution and to calculate the parameters of these distributions. The procedure included verification and validation of data, plotting the frequency distribution histograms and Q-Q plots (normal probability plots) and the use of some methods of elimination of plateaus on the Q-Q plots and the distribution recovery. As a result, in 74 of 78 analyzed regions radon concentrations conform quite well or almost perfect to a lognormal distribution up to a certain level (this level ranged from 55 to 4915 Bq/m3). For all 78 regions geometric means with 95% confidence intervals, geometric standard deviations and arithmetic means were calculated. It should be noted that due to the fact that the Federal databank is a database containing results of measurements taken with different techniques (instant measurements, charcoal canisters, radon monitors and etched track detectors), the lognormal distributions for most regions are in fact contaminated distributions, and currently it is impossible to calculate the parameters of separate distributions that form the mixture. The results show that dose assessment based on arithmetic means could lead to an  overestimation of the doses from radon up to 2.1 times compared to that based on geometric means. The calculated medians can also be used for risk assessment purposes.

Computed tomography (CT) is commonly associated with relatively high patient doses. In order to keep the patient doses from the CT examinations on the acceptable level it is necessary to apply the principle of optimization. An essential part of optimization is the achievement of the compromise between the patient dose reduction and the maintenance of the image quality that provides accurate diagnostic information. The aim of the study was to determine the relations between the patient doses, CT image quality and the parameters of the tube current modulation program (Auto mA, CareDose and DoseRight) for the examination of the chest. The study was performed on the three most common modern tomographs in Russia: Ingenuity Core 128, Philips; Optima 64, General Electric; Definition AS, Siemens. The anthropomorphic phantom Lungman (Kyoto Kagaku CO., LTD) was used in the study. In order to assess the tube current modulation for the range of tube voltage (80–120 kV), the reference mA∙s (ref. mAs), Noise Index (NI) and Dose Right Index (DRI) were changed for the CareDose (Siemens), Auto mA (GE) and RightDose (Philips),  respectively. Estimation of the effective dose was performed using the method from Methodical guidance 2.6.1.2944-11 (MU 2.6.1.2944-11). In order to evaluate the image quality, the noise of a CT image in the mediastinum was selected as the most homogenous for chest region. It was estimated, that for the GE units with Auto mA, the noise of CT image had a liner relationship with NI; the patient dose decreased with the increase of NI. For the Siemens units with CareDose, the noise of CT image decreased with the ref.mAs for the range of tube voltage (80–120 kV); the patient dose was directly proportional to the ref.mAs and increased with the tube voltage. For the Philips units with DoseRight, the noise of CT image decreased with the DRI for the range of tube voltage (80–120 kV); the patient dose was directly proportional to the DRI and had no dependence on the tube voltage. The tube current modulations are proprietary for each manufacturer; it is necessary to consider  them for the protocol development. The obtained dependences could be useful for optimization of CT protocols. 

The paper presents results of radiation monitoring of the Dehmoy tailings pond and the nearest inhabited locality, Goziyon village. It is shown that the average gamma dose rate on the surface of Dehmoy tailings pond reaches 20 μSv/h, density of radon flux from the surface reaches 65 Bq/(m2∙s), and the outdoor radon concentration at the Dehmoy tailings pond varies from 200 to 1000 Bq/m3. It was found that the activity concentration of 238U in the tailing material reaches 980 Bq/kg and the activity concentration of 226Ra reaches 7620 Bq/kg. Potential doses for three hypothetical groups of the population living in the village of Goziyon were assessed and the following sources and ways of exposure were taken into account: external gamma radiation due to soil contamination; internal exposure due to inhalation of 222Rn and its progeny, as well as longlived radionuclides with aerosols from atmospheric air; internal exposure due to ingestion of soil particles. The hypothetical doses range from 0.4 to 17.0 mSv/year. The most significant contributors to the dose are the external gamma radiation and the internal exposure due to inhalation of 222Rn and its progeny. The  contribution of internal exposure due to the ingestion of soil particles  in the case of working in windy conditions and the lift of dust from the surface of the tailings pond can also be significant. The hypothetical annual doses to three hypothetical groups of the population can be considered as the basis for estimating the safe working time at the tailings pond during its rehabilitation. The calculated dose estimate (up to 17 mSv/year) is rather high and unacceptable compared to the dose limit for the population of 1 mSv/year above the background level. 

In this article it made analysis of concepts and values used in NRB-99/2009 and a number of national methodological documents on the assessment of risks associated with irradiation. It is concluded that NRB-99/2009 violates the logic in the presentation of this issue. It can be restored if a special section is introduced in the developed NSB-2019, with more detailed coverage of the terminological and methodological aspects of the assessment of such risks. The draft section is attached to this article In the draft introduces a number of new terms (radiogenic risk, nominal radiogenic risk, radiogenic risk of death from cancer and radiogenic risk of cancer and a number of others) with a clear interpretation of their meaning and purpose, as well as the sphere application of the relevant values. The draft proposes to replace the term generalized risk with radiation risk, which is more in line with its meaning. Given also specific formulas to calculate the radiogenic risk coefficients for different types of irradiation based on the real demographics data for exposed populations. Because of the cumbersome formulas, they can be given to the Annex of the NRB-2019 or issued in methodical instructions prepared in the elaboration of the provisions of the NRB-2019.