The third article in a series of publications devoted to the results of studying the current radiation situation in the territories of the Bryansk region bordering the Republic of Belarus presents results of studies of the content  of  radionuclides  (¹³⁷Cs  and ⁹⁰Sr)  in  samples  of  agricultural  food  products  produced  in  the  personal subsidiary plots of the population. The regularities of changing ¹³⁷Cs and ⁹⁰Sr content in samples of cow’s milk and potatoes depending on the level of radioactive contamination of the territory were studied; the present values of the quantities characterizing the distribution of the ratio of the activity concentration of radionuclides in agricultural food products to the density of radioactive contamination of the soil of the territory were deter -mined. The ratios of average values of ¹³⁷Cs activity concentration in milk from stalled and grazing periods for cattle were analyzed. The results of the study show that some dairy product samples (less than 1%) do not meet the radiological safety criterion. Exceedances of the hygienic standards were not found in the studied samples of potatoes, vegetables, and meat of farm animals.

Evaluation of the low dose effect on population health is still a relevant issue. It requires further studies to improve our understanding of these effects. To solve this problem, it is important to conduct studies of the late effects of radiation exposure with direct risk estimation in the population that combines all strata of the society: people of different sex, age, initial health status, social and economic status. Moreover, this population should be sizeable and has been followed up for a long-term period. This manuscript is the first to present the findings of the analysis of the incidence risk of cancer of all the digestive organs, excluding intestines, and stomach cancer taken separately in members of the Southern Urals Population Exposed to Radiation Cohort depending on the dose accumulated in the stomach over the period from 1956 through 2018. This cohort is comprised of individuals exposed in the Southern Urals in two radiation accidents (on the Techa River and in the East-Urals  Radioactive  Trace)  over  the  period  from  01.01.1950  through  31.12.1960.  The  cohort  also  includes those who were born during this period; they could have additional in utero exposure or have exposed parents. The population was affected by long-term combined exposure (external and internal) at the low-to-medium soft tissue dose range (up to 1.1 Gy). The size of the incidence cohort was 47,282 people. Over the follow-up period 01.01.1956-31.12.2018, the number of person-years made up 1  292   930; mean dose to the stomach was 47 mGy, maximum – 1,132 mGy. Excess relative risk of the cancer incidence of the digestive organs was assessed using the Poisson regression analysis. Calculations were performed using the EPICURE Statistical software package. Excess relative risk for stomach cancer with a 2-year minimal, was 0.98/Gy (р=0.026), for  all  cancers  of  the  digestive  organs,  excluding  intestines,  –  0.58/Gy,  р=0.06.  There  was  no  significant modification of the effect by non-radiation factors. These values of excess relative risk do not disagree with the results of similar studies in the Japanese cohort of the atomic bomb survivors who were compatible in terms of age but had acute exposure at higher doses. No significant dose dependence of the cancer incidence of the oral cavity, esophagus, liver, or pancreas was detected at this stage.

Colorectal cancer (colon, rectum, rectosigmoid and anus) is one of the most frequently registered cancer sites. Apart from main risk factors for the development of cancer of this localization (dietary disorders, obesity, alcohol and tobacco use, contact with certain chemicals), a number of authors have noted in their studies the effect of ionizing radiation. The objective of this study was to directly assess the excess relative risk of colorectal cancer in the population exposed to long-term chronic radiation mainly in the range of low-dose and low  dose  rates.  These  people  are  included  in  the  Southern  Urals  Population  Exposed  to  Radiation  Cohort. Materials and methods: the analytical cohort included 47,282 people, the follow-up period was 63 years (from 1956 to 2018), and the number of person years at risk was 1,292,930. The incidence catchment area includes five Chelyabinsk Oblast raions, the cities of Chelyabinsk and Ozersk. For the period from 1956 to 2018, 462 cases of colon cancer were registered in the follow-up territory. The colon dose was used as a reference dose. The mean absorbed dose was 69 mGy, the maximum dose – 1,824 mGy. The analysis was performed using Epicure statistical package programs by Poisson regression method with a simple parametric model of excess relative risk. Significance of the results was assessed by the maximum likelihood method with 95% probability. Results: In SUPER members, baseline colorectal cancer incidence rates were found to be dependent on such factors as sex (p<0.001), ethnicity (p=0.001), attained age (p<0.001), education (p<0.001), year of birth of cohort members (p<0.001), presence of cancer in first degree relatives (p=0.03). The risk analysis did not reveal statistically significant dose dependence of the excess relative risk of malignant neoplasms of the whole large intestine, as well as no significant dependence of the excess risk of malignant neoplasms of the colon and rectum. The influence of modifying factors on the magnitude of radiogenic risk was evaluated. Assessment of the excess relative risk of colorectal cancer in this cohort is carried out for the first time.

In  the  Russian  Federation,  there  is  a  constant  increase  in  the  number  of  radiation  medical  installations  with electron accelerators. Over the past 4 years, their number has increased 2.5 times. These installations contain pulsed electron accelerators that generate pulsed bremsstrahlung radiation with a maximum energy from 6 to 21 MeV. Currently, there are no devices designed for dosimetry of the pulsed photon radiation with energy of more than 10 MeV in the state register of measuring instruments of the Russian Federation. The most widely used radiation monitoring device for pulsed electron accelerators is the DKS-AT1123 X-ray and gamma radiation dosimeter designed for dosimetry of pulsed bremsstrahlung radiation with an energy of up to 10 MeV. The purpose of this work is to evaluate the possibility of using this device for dosimetry of pulsed bremsstrahlung radiation with a maximum energy of up to 20 MeV. The authors calculated the energy spectra of bremsstrahlung radiation for a point source with a maximum energy of 20 MeV behind flat concrete screens with a thickness of 1 m, 2 m and 3 m by the Monte Carlo method using the GEANT4 calculation program. The energy dependence of the registration efficiency of the DKS-AT1123 dosimeter was extrapolated to the energy range of 10–50 MeV in the kerma-approximation without taking into account the energy transfer by secondary electrons. It was assumed that it corresponds to the energy dependence of the total mass attenuation coefficient for the absorbed energy of gamma quanta in water. Using conversion coefficients for converting the fluence of monoenergetic photons into the effective dose rate at an anterior-posterior radiation incidence on the human body, real dose rates were calculated, and using the energy dependence of the dosimeter readings, the predicted results of measuring the unit dose rate with the DKS-AT1123 dosimeter behind a concrete protection with a thickness of 1, 2 and 3 m were obtained. It is shown that the maximum expected underestimation of the measurement results will not exceed 40% and practically does not depend on the thickness of the concrete shield in the thickness range from 1 to 3 m. To account for this underestimation, it is necessary to use the value of additional measurement error due to the energy dependence of the sensitivity of this device for the photon radiation energy of more than 10 MeV, equal to 70%. This makes it possible to use the measurement results obtained using this dosimeter to adequately characterize the state of radiation safety during operation of pulsed electron accelerators with a maximum energy of up to 20 MeV. It is possible to use a correction factor to the measurement results equal to 1.63 ±0.04 to compensate for this underestimation. The proposed approach can be used to create a methodology for using this dosimeter for radiation monitoring of medical electron accelerators with the energy of up to 20 MeV, if there are correction factors for radiation protection configurations and radiation energies encountered in practice.

In the paper, based on the analysis of scientific information regarding the parameters and characteris-tics of radiation fields for three dental X-ray procedures (intraoral radiographs, panoramic radiographs on orthopantomographs and computed tomography), the required thickness of stationary shields for rooms with different X-ray equipment is calculated. It has been shown that in most cases, in rooms where intraoral and panoramic radiographs are taken, conventional 20 mm thick plasterboard interior room partitions provide the necessary protection to comply with the dose limit for the population in the adjacent room. For the rooms where dental examinations are carried out using computed tomographs additional lead shield up to 1.5 mm thick is required depending on the conditions and the category of protected persons in the adjacent room.

Cytogenetic Fluorescence In Situ Hybridization studies, that allow assessing the frequency of stable chromosome  aberrations  in  circulating  T  lymphocytes,  are  commonly  used  in  retrospective  dosimetry  in  cases of uniform whole-body exposure. In the event of ^89,90Sr exposure, interpretation of cytogenetic data is challenging,  especially  if  blood  sampling  occurs  long  after  the  start  of  exposure.  The  weighted  average  dose  to T-lymphocytes at the time of donor blood sampling in the long-term period after exposure to ^89,90Sr does not coincide  with  the  red  bone  marrow  dose.  Previously,  we  developed  a  model  that  allows  us  to  estimate  the weighted average doses to T-lymphocytes upon ^89,90Sr ingress into the body of people belonging to various age groups. In this study, the modeling results were used to estimate the conversion factors from the frequency of translocations to the red bone marrow dose, which is important for assessing radiobiological effects associated with hematological diseases. The objective of our study is to estimate numerically the conversion factors (B_rbm) from the dose to lymphocytes to the dose to red bone marrow for various scenarios of ^89,90Sr ingestion depending on age, sex, and time after the start of exposure. The following scenarios are considered: single, uniform chronic for six months, uniform chronic for 1-5 years, non-uniform intake for 5 years (simulates the dynamics of intake in the Techa riverside settlements in 1950-1954). As a result, it has been found that the B_rbm values significantly depend on the age at the time of ^89,90Sr intake. The older the person is at the start of exposure, the more the cytogenetic dose differs (it is significantly lower) from the dose to the red bone marrow. We can say that the cytogenetic dose corresponds to the red bone marrow dose only in newborns and infants. This is due to the age-related dynamics of T-cell populations. Sex does not have a significant effect on B_rbm. The effect of the ^89,90Sr intake duration on B_rbm is the most pronounced for 15-year-old adolescents. For them, the difference in B_rbm values for a single and chronic 5-year ingress reaches 13%. Non-uniform intake of ⁹⁰Sr over several years does not have a significant effect on B_rbm and can be modelled by a uniform intake of the same duration.

The study assessed the acceptability of the currently existing approach to calculating shielding in computed tomography rooms and formulated proposals for its improvement, taking into account the parameters of research in domestic medical practice. It is proposed to use the dose-length product as the main measured parameter in the new approach to calculating shielding. Typical tomograph workload values of dose-length product, typical for examinations in the Russian Federation, were assessed. Using thermoluminescent detectors, the experimental assessment of the distribution of absorbed dose in the air in a computed tomography room was carried out. The experimental results showed that the distribution of of X-ray exposure in the central plane is not isotropic. Due to the attenuation of exposure by the gantry design, “shadow” zones are observed, where  the  absorbed  dose  reduction  in  the  air  reaches  10-13  times  compared  to  its  level  in  the  direction  of couch movement. Based on the results of measurements of the distribution of absorbed dose in air, the relative scatter coefficients were calculated. The workload was determined for 7 tomographs (1 in St. Petersburg and 6 in Moscow). For each tomograph, the average weekly number of head and body examinations and the values    of dose-length product for these areas were assessed, taking into account the number of multiphase examinations. The obtained workload values   turned out to be one or two orders of magnitude higher than those currently used in calculating shielding. Based on the results of the study and literature data, the work proposes a  new  approach  to  calculating  shielding  in  computed  tomography  rooms,  based  on  the  value  of  measured dose-length product during the examination and allowing to take into account the specifics of the operation of the device.

The article proposes a new approach to assessing the effective doses of flaw detectorists performing flaw detection using portable radionuclide flaw detectors (gamma flaw detectors). The existing approach to assessing effective doses, based on the use of one individual dosimeter placed on work clothes in the chest area, is inadequate for the actual working conditions of exposure of flaw detectorists. Gamma flaw detectors contain a closed man-made source of ionizing radiation in their head, therefore, even in the non-working position, such flaw detectors pose a radiation hazard. When transporting and preparing gamma flaw detectors for work, the flaw detector operator is in close proximity to the radiation source. The irradiation geometry changing during the technological cycle when working with portable gamma flaw detectors at certain stages creates a sharply uneven  irradiation  of  the  flaw  detectorist’s  body.  Therefore,  after  assessing  the  stages  of  the  technological cycle, an option was proposed for a more conservative assessment of effective doses – to change the location of the individual dosimeter on the working clothes of the flaw detectorist, moving the individual dosimeter to the abdominal area. An anonymous study was carried out with the participation of 15 flaw detectorists; three individual dosimeters were displayed on their working clothes: two of them were experimental and were placed in the chest and abdomen; the third (a control dosimeter) was exposed for the quarter on the chest as part of constant individual dosimetric monitoring. In controlled anonymous measurements, the average effective dose, estimated from the readings of dosimeters exposed in the chest area, was equal to 0,95 mSv (median – 0,92 mSv, maximum value – 1,27 mSv). These values were compared with values obtained using dosimeters that were exposed to the abdomen, and the differences were significant (the average effective dose was 1,24 mSv (median – 1,22 mSv, maximum value – 1,78 mSv).

The paper presents the results of analysis of the Ivanovo Regional databank of radiation doses to the pub-lic from exposure to natural and technologically enhanced radiation background for 2008–2022. Despite the fact that the average individual annual effective dose of public exposure due to natural sources of radiation in the Ivanovo region calculated for the whole 15-year period (4.63 mSv/year) does not qualify as increased (i.e.  does  not  exceed  the  level  of  5  mSv/year),  in  some  years  of  the  period  under  review  the  average  dose repeatedly exceeded this level, reaching 7.50 mSv/year. The analysis of the structure of the doses of public exposure due to natural sources of radiation in the Ivanovo region showed that the contribution of the dose from  internal  exposure  to  radon,  thoron  and  progenies  according  to  measurement  results  from  2008–2022 ranged from 65.98 to 81.47%. The paper provides examples of buildings of different types in settlements of the Ivanovo region, in which the indoor radon isotopes equilibrium equivalent concentrations are more than 1.5 times higher than the established action level for existing dwellings and public buildings (200 Bq/m³). Despite the  significant  amount  of  measurement  data  in  the  Regional  databank,  it  is  necessary  to  obtain  additional information on the indoor radon levels in existing wooden and other low-rise dwellings and public buildings in the most radon-prone areas of the region. For this purpose, a radon survey is planned for 2024-2026 in the cities  of  Ivanovo  and  Kohma,  Privolzhsky,  Gavrilovo-Posadsky,  Teykovsky  and  Zavolzhsky  districts  of  the Ivanovo  region  within  the  framework  of  a  joint  project  of  Saint-Petersburg  Research  Institute  of  Radiation Hygiene after Professor P.V. Ramzaev, the Directorate of the Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing in the Ivanovo region, and the Center of Hygiene and Epidemiology in the Ivanovo region.

Radiopharmaceutical therapy with ¹³¹I has been one of the most common types of radiopharmaceutical therapy  for  many  years.  Radiation  safety  of  the  public  is  ensured  by  limiting  the  patient  contacts  until  the radiological parameters are reduced to the established criteria. To increase the availability of the radiopharmaceutical therapy with ¹³¹I, softer patient release criteria for ¹³¹I have been proposed. However, early patient release may increase exposure to the public, e.g. in transport. The aim of the work is to evaluate the radiation exposure  from  patients  with ¹³¹I -MIBG  and  Na¹³¹I on  the  public  in  transport  considering  the  generation  of biological waste. In this work, ¹³¹I excretion from the body of patients in transport was evaluated for different scenarios of patient travel to the place of residence. As a result, it was found that mitigation of patient release criteria leads to an increase in the effective dose to the public in transport and an increase in the ¹³¹I activity excreted with patient waste. The specific activity in the tanks of biotoilets in transport, generated after the pas -sage of a patient with injected ¹³¹I -labeled radiopharmaceuticals, exceeds the limit value of classifying liquid waste as radioactive. To optimize radiation protection of the public, it is advisable to apply a differentiated approach to release patients after therapy with ¹³¹I: to group non-resident patients into a separate category retaining for them the established release criterion (without mitigation) to minimize the radiation impact on the public.

The  article  presents  results  of  the  analysis  of  questionnaire  survey  data  on  preferences  in  the  choice  of  cooking methods of different types of forest mushrooms by residents of the most contaminated south-western  districts  of  the  Bryansk  region  in  the  remote  period  after  the  Chernobyl  accident.  In  the  period  from  2019  to 2022, the employees of Federal Budgetary Institution of Science «Saint-Petersburg Research Institute of  Radiation Hygiene after Professor P.V. Ramzaev» conducted a face-to-face questionnaire survey of the adult  population.  In  addition  to  general  questions  about  the  respondent,  the  questionnaires  included  questions  about the species composition of the mushroom basket, the volume and proportion of consumption of each type  of mushroom by the respondent and his family members (both in the current and last year), as well as methods  of culinary processing of the mushrooms consumed. Based on the analysis of individual survey data, a group  of 1 311 respondents, whose diet included various types of mushrooms, was selected. Analysis of the survey  results showes that respondents prefer to process a large proportion of freshly picked forest mushrooms (59%)  for  long-term  storage  (pickling,  freezing,  drying,  salting,  etc.);  41%  of  mushrooms  are  consumed  immediately. The most popular pretreatments of freshly picked mushrooms are washing and boiling (34 and 26%,  respectively). When freezing, pickling and pickling up to 97% of respondents carry out pre-treatment (rinsing,  soaking and / or boiling) of freshly picked mushrooms. Less popular methods of the mushroom preparation  (from 2 to 4%) are pickling, drying and frying of fresh mushrooms with their subsequent preservation. Thus,  the majority of respondents actively use various types of culinary processing with the use of preliminary stages  of technological processing in the form of rinsing, soaking and (or) boiling. The use of the above methods of  pre-cooking of freshly harvested mushrooms leads to a decrease in the  ¹³⁷Cs content in the consumed product.

The Arctic zone is a strategically important territory of the Russian Federation from the point of view of socio-economic, scientific, and technological components, as well as in terms of planning the development of a system for ensuring national defense, state, and public security. Intensive exploration and development of Arctic territories, combined with a rapidly changing environment due to global climate change, carries a few risks for the environment. This determines the need to assess potential environmental damage and determine the significance of factors of potential negative impact on unique Arctic ecosystems now and in the future. The article presents current data from a radiation survey of the coastal zone of residential areas close to the site of the sinking of the nuclear submarine ‘K-159’ – Teriberka village and Kildin Island, Murmansk region, as well as the sea area to assess the primary levels of man-made and natural radionuclides before starting work on the potential lifting of the submerged object. This work was carried out as part of the implementation of the State Program of the Russian Federation ‘Health Development’ (approved by Decree of the Government of the Russian Federation dated December 26, 2017, No. 1640). The results of measuring the ambient dose equivalent rate of gamma radiation in open areas and determining the content of man-made and natural radionuclides in samples of environmental media (soil, aquatic vegetation, marine aquatic organisms) and food products of local origin and production (mushrooms, berries, fish, milk). The research results showed that the state of the study area is generally stable in terms of the radiation factor, the content of radionuclides is at the background level. As part of this work, electronic database modules have been developed based on the results of radiation monitoring in Teriberka village and on Kildin Island. Certificate No. 2022621890 was received on registration of a database with the results of the radiation situation of the above-mentioned territories.

The paper presents comments, remarks and opinions on the material presented in the publication “Radon regulation crisis in Russia: scale of the problem and proposals for remediation” by Tsapalov A., Miklyaev P., Petrova T., Kuvshinnikov S., published in the Russian peer-reviewed journal “ANRI” (“Radiation measurement equipment and news”), 2024, No. 1.

The paper (in two parts) presents an overview of the new guidelines MR 2.6.1.0333-23 (approved on 01 December 2023) that supersede guidelines MU 2.6.1.2838-11, which were used for organizing radiation surveys of residential, public and industrial buildings and facilities and their sanitary assessment in terms of radiation safety indicators over the past 12 years. Due to a large number of critical comments on the document received during this period, a need for significant revision emerged. The scope of the revised document was expanded and now covers all stages of the life cycle of buildings and facilities: commissioning; operation period; overhaul and reconstruction; demolition. In the first part of the paper, the structure and legal status of the new guidelines are considered, as well as the main innovations in terms of measuring the ambient dose equivalent rate of gamma radiation, searching and identifying local radiation anomalies and sites of radioactive contamination, measuring surface contamination levels, and determining the minimum number of premises to be surveyed. The reasons for the introduction of certain changes are outlined. The issues of evaluation of measurement uncertainty, reporting of measurement results and registration of test reports are covered in detail. In the second part of the paper, numerous innovations will be considered in terms of estimating the indoor average annual equilibrium equivalent concentration of radon isotopes.

Activities of gamma-emitting radionuclides were measured in glassy inclusions (particles) found in soil samples from the “Taiga” peaceful nuclear explosions site (the Perm region, Russia). The measurements were performed using a stationary semiconductor gamma spectrometer. Activity concentrations were determined for the following technogenic radionuclides: ⁶⁰Co, ⁹⁴Nb, ¹³⁷Cs, ¹⁵²Eu, ¹⁵⁴Eu, ¹⁵⁵Eu, and ²⁴¹Am. The activity concentrations of ²⁴¹Am in the glassy inclusions were one to two orders of magnitude higher compared to the level of minimum significant activity concentration (1 Bq/g for ²⁴¹Am) established by the Russian Radiation Safety Standards “NRB-99/2009”. Earlier, exceeding this level for the ²⁴¹Am activity concentration in the native (unfractionated) soil samples from the “Taiga” site was reported by other researchers. In accordance with current Russian legislative and regulatory provisions regarding use of nuclear charges for peaceful purposes, the soil and radioactive glassy inclusions found in the soil correspond to the category of special radioactive waste. Considering the long half-life of ²⁴¹Am (432 years), radiologically significant contamination by this radionuclide will persist at the “Taiga” site for the foreseeable future.