Occupational Exposure in Radiation Applications in India: Trends and Distribution Analysis

Occupational exposure data in radiation applications provide a good insight on the radiation risks to workers from occupational hazards, the safe practices adopted and in deriving methods to prevent possible radiation exposures. The analysis of occupational exposure may be used to provide regulatory guidance and more focused attention to improve the safety systems, thus improving the personnel and environment safety. In this study, occupational exposure from radiation applications during 2004–18 amounting to a total number of 1951 486 occupational dose data are collected and analysed using the statistical software package, SPSS. As recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation, four critical parameters viz., annual collective effective dose, average annual effective dose, individual dose distribution ratio and the annual collective dose distribution ratio for each practice are estimated. Using the trend observed for these parameters, it is predicted that occupational exposure in diagnostic radiology in the year 2023 would increase by 80% in total number of monitored with 76% increase in average collective dose and no significant change in average annual effective dose. In the same manner, nuclear medicine would see 28% of increase in radiation workers with the increase of 24% in collective dose with no significant change in average annual effective dose. Further, the reasons and area of regulatory focus for the different practices are discussed.

REASSESSMENT OF RADIATION EXPOSURES OF UNDERGROUND NON-URANIUM MINE WORKERS IN WESTERN AUSTRALIA

In the 1990, radon and radon progeny was reported to contribute approximately 70% of the average 1.4 + 1.0-mSv annual dose across 26 Western Australian underground non-uranium mines. The Western Australian underground mining workforce has expanded significantly, and parameters used to calculate doses have changed significantly, warranting a review of the 1990’s data. The review concludes that doses received by the contemporary mining workforce has increased on average, by 5.4%, with annual dose estimates ranging from 0.53 to 3.56 mSv, with a mean of 1.33 mSv. Doses in 12 of the 23 underground mines exceed 1 mSv and are required to comply with radiation safety legislation. It is estimated that 5400 underground workers will fall into the greater than 1-mSv category. The collective dose to the underground worker population has increased by 4.5 times from 3060 man mSv (2173 workers) to 13 669 man mSv (8597 workers).

PRELIMINARY ASSESSMENT OF STRUCTURE AND COLLECTIVE DOSE FROM CT EXAMINATIONS RELATED TO COVID-19 DIAGNOSTICS IN THE RUSSIAN FEDERATION IN MARCH -JUNE 2020

The use of computed tomography (CT) for the diagnostics of COVID-19 in the Russian Federation led to significant changes in the structure of X-ray diagnostics and levels of medical exposure of the patients. This study was aimed at the preliminary operative assessment of changes in the structure and collective dose from CT examinations in several representative hospitals, regions and on the level of the Russian Federation. The results of the study indicate that during the transformation of hospitals from general medical practice into dedicated COVID-19 facilities, the number of CT examinations increased up to 30%; the collective dose from CT exams increased up to a factor of 1.5. During a partial transformation of a medical facility into the hospital with separate COVID-19 departments, the increase in the number of CT examinations in the facility was more significant (up to a factor of 2 or more). These numbers correspond to 1.5 - 2.5 chest CT examinations (from 1 to 6) per patient admitted to hospital with COVID-19 diagnosis; and 1.2 chest CT examinations per patient in outpatient facilities, including a mandatory CT scan for the staging of COVID-19. The collective dose from CT examinations in the Russian Federation for March-June period of 2020 increased by the factor of 2 (from 16k man-Sv to 32k man-Sv); the collective dose of COVID-19 patients was about 12k man-Sv. For a more detailed and reliable assessment of the dynamics of changes in the structure of diagnostic radiology and levels of radiation exposure of patients in the Russian Federation, data collection in the regions of the Russian Federation and individual medical facilities will continue.

Monitoring of Tritium Internal Exposure Doses of Heavy-Water Reactor Workers in Third Qinshan Nuclear Power Plant

To analyze the tritium internal exposure dose of workers in the Third Qinshan Nuclear Power Plant over the past 15 years. Urine samples provided by workers are tested directly to analyze the tritium concentrations and estimate internal exposure dose. Since 2004, an average of approximately 1600 workers have been monitored annually, with an average annual monitoring frequency of approximately 11 000. Since 2004, the average annual collective dose of tritium internal exposure was 149.62 person·mSv, accounting for 19.07% of the total annual collective dose. A total of 18 workers’ annual individual internal tritium radiation doses exceeded 2 mSv, of which 5 workers’ internal tritium radiation doses in a single intake exceeded 2 mSv. The occupational population with the largest total internal tritium radiation doses consists of maintenance personnel, fuel operators, and radiation protection personnel, whose collective doses of internal exposure account for 75.51% of the total collective doses within the plant. Over 15 years of operation, the internal tritium radiation doses of workers in the Third Qinshan Nuclear Power Plant have been strictly controlled within the national regulatory limit and power plant management target, ensuring the health and safety of the workers.

The 1957 accident: radiological situation and radiation doses of participants in the liquidation of the accident on the territory of PA “Mayak” industrial site

Purpose: to assess the radiation situation on the industrial site of the PA “Mayak” during the accident in 1957 and the radiation doses of the participants in the liquidation of consequences of this accident. Materials and methods: on the basis of the archival documents analysis, radiation situation data for 1957 – 1960, IDC data and calculated doses of the Mayak workers, as well as supporting organizations personnel and military units involved in the liquidation of the accident consequences and covered by individual monitoring are presented. Results: in 1957 – 1959 about 38,5 thousand people took part in the works on the territory of the PA “Mayak” industrial site for liquidation of consequences of the accident, including persons exposed at the time of the accident: employees of “Mayak”, military and civil builders. Radiation doses from 25 to 30 R received about 10,5 thousand people, while there were single cases of exposure in doses up to 100 R. Conclusion: the collective dose received during the accident and liquidation of its consequences in 1957 was about 820 000 person-R. Collective doses recorded in 1958 and 1959 amounted to 250 000 person-R and 54 000 person-R, respectively.

Radiation-hygienic monitoring and assessment of the doses of the public residing on the radioactively contaminated territories of the Tula region

Aim of the study: analysis of the results of the radiation-hygienic monitoring of the territories of the Tula region, contaminated due to the Chernobyl NPP accident; concentration of 137Cs and 90Sr in the locally produced food products and analysis of the annual effective dose of the public. Materials and methods: the study was performed in the Tula region in 1997-2018. It included the evaluation of the indicators of the radiation safety of more than 50 thousand samples of the main food products, sampled in the areas of the radioactive “Chernobyl” contamination of the region with the simultaneous measurement of the external gamma-radiation dose rate in the stationary control points. Additionally, it included the assessment of the dynamics of concentration of 137Cs and 90Sr in food products, maximal values of mean annual effective doses of the public and contribution of the collective dose from medical exposure into the structure of the annual collective dose of the public. Results: The study allowed estimating the concentration of 137Cs and 90Sr in the main local food products. Estimated values of gamma radiation dose rate were stable and laid in the range of normal variations specific to the middle latitudes of the European part of Russia. The values of maximal mean annual effective doses of the public indicate the stable radiation environment and do not exceed 1 mSv. It should be mentioned that the contribution of collective dose from medical exposure into the annual collective dose of the public as well as the values of mean individual effective doses from medical exposure are reducing with the increase in the number of X-ray examinations. Conclusions: The lack of exceedances of the permissible levels of 137Cs and 90Sr in the locally produced food products and the reduction of the mean annual effective dose of the public indicates the possibility of the transfer of the settlements affected by the Chernobyl NPP accident into the normal living conditions within the program of the transfer of the settlements from the “Chernobyl” zone.

RESULTS OF RADIATION AND HYGIENIC PASSPORTIZATION OF THE CITY OF MOSCOW IN THE PERIOD FROM 2013 TO 2016

Introduction. The article discusses the results of a general analysis of information on the radiation-hygienic passports of Moscow in the period from 2013 to 2016, providing objective and accessible information about the characteristics of all sources of ionizing radiation (man-made, medical, natural) and the resulting radiation doses for the population Moscow. Material and methods. A qualitative and quantitative assessment of doses for the population from natural sources, medical exposure of patients during X-ray examinations was carried out, the objects of Moscow using sources were studied. Results. The number of sources in Moscow has been established to be indicated inaccurately, as a result of which unaccounted sources are identified during control and supervisory measures. The leading role in the structure of collective doses of radiation to the population of Moscow according to the data of 2016 was shown to come from natural sources and medical research as much as 81.5 and 18.3%, respectively. A continuous increase in the dose from computed tomography and its significant contribution to the collective dose from medical exposure of Moscow residents was noted. In 2016, its contribution amounted to 59.9%. Discussion. To determine the qualitative and quantitative assessment of the doses to the population of Moscow from all sources, the radiation hygienic passports of the city of Moscow were studied from 2013 to 2016. Conclusions. On the basis of the study conducted to assess the doses of radiation to the population of Moscow, an underestimation of the effective doses of patients during medical research was established. There is a continuous increase in the dose from computed tomography, its significant contribution to the collective dose from medical exposure of the population of Moscow. In order to update the radiation hygienic passport of Moscow, it is necessary to achieve the presentation of complete information by objects using sources, as well as the relevance of legal acts, taking measures to prevent an unreasonable increase in doses of medical exposure to residents of Moscow while actively introducing highly informative diagnostic methods in medicine.

Modern principles of the radiation protection from sources of ionizing radiation in medicine. Part 1: Trends, structure of x-ray diagnostics and doses from medical exposure

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.