Comparative Analysis of Approaches to Regulation and Monitoring of Workers for Internal Radiation Exposure

Purpose: Harmonization and improvement of the system for regulating the internal radiation exposure of workers and the basic requirements for ensuring radiation safety with international requirements and recommendations. Material and methods: Issues related to the development of approaches to regulation and monitoring of workers for internal radiation exposure in the process of evolution of the ICRP recommendations and the national radiation safety standards, are considered. The subject of analysis is the standardized values: dose limits for workers and permissible levels as well as directly related methods of monitoring of workers for internal radiation exposure, whose purpose is to determine the degree of compliance with the principles of radiation safety and regulatory requirements, including non-exceeding the basic dose limits and permissible levels. The permissible levels of inhalation intake of insoluble compounds (dioxide) of plutonium-239 are considered as a numerical example. Results: Based on the analysis of approaches to the regulation and monitoring of workers for internal radiation exposure for the period from 1959 to 2019, it is shown that a qualitative change in the approach occurred in the 1990s. It was due to a decrease in the number of standardized values by introducing a single dose limit for all types of exposure: the effective dose E, which takes into account the different sensitivity of organs and tissues for stochastic radiation effects (WT), using the previously accepted concepts of the equivalent dose H and groups of critical organs. From the analysis it follows that the committed effective dose is a linear transformation of the intake, linking these two quantities by the dose coefficient, which does not depend on the time during which the intake occurred, and reflects certain exposure conditions of the radionuclide intake (intake routes, parameters of aerosols and type of radionuclide compounds). It was also shown that the reference value of the function z(t) linking the measured value of activity in an organ (tissue) or in excretion products with the committed effective dose for a reference person, which is introduced for the first time in the publications of the ICRP OIR 2015-2019, makes it possible to standardize the method of measuring the normalized value of the effective dose. Based on the comparison of the predicted values of the lung and daily urine excretion activities following constant chronic inhalation intake of insoluble plutonium compounds at a rate equal annual limit of intake (ALI) during the period of occupational activity 50 years it was shown that the modern biokinetic models give a slightly lower level (on average 2 times) of the lungs exposure compared to the models of the previous generation and a proportionally lower level (on average 1.4 times) of plutonium urine excretion for the standard type of insoluble plutonium compounds S. However, for the specially defined insoluble plutonium compound, PuO2, the level of plutonium urine excretion differs significantly downward (on average 11.5 times) compared to the models of the previous generation. Conclusion: With the practical implementation of new ICRP OIR models, in particular for PuO2 compounds, additional studies should be carried out on the behavior of insoluble industrial plutonium compounds in the human body. Besides, additional possibilities should be used to determine the intake of plutonium by measuring in the human body the radionuclide Am-241, which is the Pu-241 daughter. To determine the plutonium urine excretion, the most sensitive measurement techniques should be used, having a decision threshold about fractions of mBq in a daily urine for S-type compounds and an order of magnitude lower for PuO2 compounds. This may require the development and implementation in monitoring practice the plutonium-DTPA Biokinetic Model.

Boris Belousov, Talented Scientific Chemist Dedication Page of Biography

The article contains material on scientific activity of the famous scientific chemist B. Belousov, the head of the laboratory of the Institute of Biophysics of the Ministry of health of the USSR, the creator of an effective anti-radiation drug, the author of the invention of the vibrational reaction Belousov-Jabotinsky.

Harmonization of the Russian Federation Legislation with Current International Recommendations

Purpose: Harmonization of the Russian Federation legislation with current international recommendations Results: The concept of the radiation safety system has been significantly modified by recommendations of ICRP (2007) and IAEA (2014). An analysis of existing international regulatory framework for radiation safety allowed to identify the main provisions to be implemented in the Russian legal and regulatory framework. It’s showed that the current Federal Law of 09.01.1996 No. 3-FZ «On Radiation Safety of Population» must be ultimately revised to be harmonized with international documents. General approaches to legal regulation of radiation safety should be essentially modified to create a strong relationship between this law and other regulatory and legal documents in force in the Russian Federation. Conclusion: An article-by-article analysis of the current Federal Law of 09.01.1996 No. 3-FZ «On Radiation Safety of Population « showed the need to modify 22 existing articles and add 12 new articles in order to harmonize it with international documents. Given such a large volume of modification it is advisable to pass a new law with simultaneous abolition of the current federal law. A new name has been proposed: Federal Law of the Russian Federation «On Radiation Safety in the Russian Federation». The enactment of the Federal Law of the Russian Federation «On Radiation Safety in the Russian Federation» with the main by-laws approved by the Russian Federation Government – «Radiation Safety Standards» and «Basic Rules for Ensuring Radiation Safety» – will allow to establish an actual regulatory framework for ensuring radiation safety of personnel and population in Russia.

Possibilities of Local Microwave Hyperthermia in Oncology

The review analyzes the features of the interaction of electromagnetic (EM) energy with various tissues and the temperature distribution in model, experimental and clinical studies from emitters for external and intracavitary microwave hyperthermia (MWHT). The effect of MWHT on the antitumor efficacy of radiation (RT) and / or chemotherapy (CT), as well as toxic effects on normal tissues, was studied. Based on the literature data and our own experience, some approaches to the treatment of cancer patients have been identified. The general principles of the method, the design features of the applicators and their role in creating a hyperthermic regime in tumors of superficial and subsurface localization are also considered. The development of methods for thermometric control and supply of the EM field, allowing relatively uniform heating of tumors, as well as the determination of the minimum effective thermal doses, remains a priority area of research both in MW and other hyperthermia methods. Based on the literature data and our own experience, some approaches to the treatment of cancer patients have been identified.

Total Brain Irradiation for Metastatic Lesions in Breast Cancer Patients

Purpose: Brain metastasis (BM) has a significant negative impact on the survival of breast cancer patients. An intensive search is underway for a multi-modal approach to identify the most effective methods of treating such patients. Material and methods: The study included 40 patients with breast cancer who were diagnosed with BM on magnetic resonance imaging (MRI) of the brain. Total brain irradiation (TBI) up to 30 Gy (3 Gy) was used as the main treatment method. The median age was 48 (31–70) years. In 75 % of cases, a nonluminal subtype of breast cancer was found, in 57.5 % of cases–T2 breast cancer, in 70 % of cases–N0-1. Results: The median survival after TBI was 12 months, 6-month survival rate was 70 %, and 12 – month survival rate was 47.5 %. The risk of death was significantly increased (HR=3.309; 95 % CI: 1,184 – 9,250, p=0.023) in patients whose time interval from the manifestation of 1 relapse to BM was ≤24 months. In these patients, the survival was only 9.5 months and was significantly lower (p=0.0136) than in the patients with the same time interval was >24 months – 30 months. Conclusions: It was found that the effectiveness of total brain irradiation in patients with breast cancer brain metastasis is the highest if the time interval from the moment of manifestation of first relapse to brain metastasis is more than 24 months.

Analysis of the Appearance of Micronuclei in the Erythrocytes and Activity of Bone Marrow Cells Proliferation after the Prolonged Low Dose Fast Neutrons Irradiation of Mice

Purpose: To analyze the level of cytogenetic damage and the activity of bone marrow cells proliferation in C57BL/6 mice after prolonged fast neutrons low dose irradiation at 10–500 mGy. Material and methods: Male C57BL/6 mice at the age of 7–8 and 16 weeks were used in the experiments. Irradiation was carried out on an OR-M installation in the field of fast neutrons and gamma quanta using five Pu(α,n)Be radionuclide sources with a high fast neutron yield at a dose rate of 2.13 mGy/h. The frequency of polychromatophilic (PCE) and normochromic (NCE) erythrocytes with micronuclei (MN) and the ratio of PCE and NCE were analyzed using light microscopy after cytochemical staining of the bone marrow cells of control and irradiated mice. The proliferation activity of bone marrow cells was determined by the number of Ki-67+-cells. The parameters of the cell cycle and the level of apoptosis were studied after DNA staining with DAPI using flow cytometry. Statistical processing of the results was carried out according to the Student’s method using the computer program Origin. Results: It was found that prolonged irradiation of mice with fast neutrons at a low dose rate (2.13 mGy/h) at doses from 10 to 500 mGy after 24 h led to statistically significant increase in the frequency of PCE with MN at all studied doses. No dose dependence of this parameter was observed in the studied range. The increase in the frequency of PCE with MN at a dose of 500 mGy was prolonged and persisted for at least 72 h. A significant increase in the frequency of NCE with MN 24 h after irradiation was found only at a dose of 500 mGy, which persisted up to 48 h. At this dose, there was also a decrease in the number of nucleated cells in the bone marrow 24 – 72 h after exposure, a decrease in the number of Ki-67+-cells 24 h after irradiation of mice, a block of the cell cycle in the G2/M phase, and a decrease of cells in the G0/G1 phase, but after 48 h, there were no disturbances in the cell cycle. Conclusion: It has been shown that after a single total prolonged irradiation of mice at low doses (10–500 mGy), when analyzing the frequency of PCE with MN, cytogenetic damage is recorded in the bone marrow, which indicates the genetic danger of exposure to even such low levels of fast neutron irradiation. A decrease in Ki67+ cells and cell cycle arrest at the G2/M phase were found only after irradiation of mice at a dose of 500 mGy and only 24 h after exposure, while the number of nucleated cells in the bone marrow at this dose was reduced, at least to 72 h.

Psychophysiological Adaptation of a Patient with Acute Radiated Sickness of Average Degree and Acute Leukemia

Purpose: Clinical and psychophysiological assessment of the adaptation of a patient who suffered from acute radiation sickness of moderate severity after the Chernobyl accident and acute leukemia, which began 30 years after the transferred ARS. Material and methods: A clinical and psychophysiological examination of a patient who suffered from acute radiation sickness of moderate severity after the Chernobyl accident and acute leukemia that occurred 30 years after the Chernobyl accident was carried out. The object of the study was the patient D.R.I., born in 1950, deputy. Head of the Chernobyl NPP workshop, participant in the liquidation of the consequences of the 1986 Chernobyl accident. On April 26, 1986, during an emergency, he underwent relatively uniform beta-gamma radiation with the development of ARS II (moderate) severity. Within 3.5 hours after the accident was in the premises of the Chernobyl nuclear power plant. In the structure of ARS, bone marrow syndrome of the second degree and oropharyngeal syndrome of the first degree of severity were observed. The radiation dose, according to a cytogenetic study, was 3.4 Gy. A psychophysiological study was carried out using the MMPI methodology, the Cattell’s 16 Personality Factors Test, the Expert automated software and methodological complex, designed to study the personality characteristics of a person, the cognitive and intellectual characteristics of a person, the Raven’s Progressive Matrices, simple and complex sensorimotor reactions and reactions to a moving object, 15 (2001) and 30 years (2016) after the Chernobyl radiation accident. Results: The clinical and psychophysiological assessment of the personality and the actual mental state made it possible to determine the demonstrative-hypochondriacal type of disturbance in the psychophysiological adaptation with the tendency for the anxiety-depressive behavior of the patient to progress to a state of increasing depression, more pronounced in dynamics. Conclusion: The psychophysiological assessment of the personality and current mental state of the patient who had ARS, moderate and, 30 years after the Chernobyl accident, acute leukemia showed a demonstrative-hypochondria type of adaptation disorder, as a variant of a disharmonious combination of hypochondria, anxiety-depressive and demonstrative tendencies with a predominance of demonstrativeness (the first, second and third scale of the MMPI methodology) with a significant decrease on the ninth scale in the form of an increase in depression in dynamics. The prevalence of demonstrativeness over growing depression in a person with high intellect, good figurative and logical thinking, and a lack of sensorimotor inhibition is a manifestation of optimism and resistance to a serious illness.

Comparison of Radiation Risk of Cancer Incidence among PA Mayak Workers Hired at Different Calendar Periods

Purpose: comparative epidemiological analysis of cancer incidence rates among PA Mayak workers hired at different calendar periods. Material and Methods: The cohort of PA Mayak workers hired at reactors, radiochemical, plutonium, water preparing and repair plants in 1948-1982 was selected for analysis of solid cancer (except lung, liver and bone) incidence. The cohort was divided into two subcohorts 1948-1958 and 1959-1982 years of hire. Regression models of relative risk included the description of background rates and excess radiation risk was used. Results: The radiation relative risk per 1 Gy was (ERR/Gy: 0.11; 95 % CI: 0.02; 0.21) in the subcohort of workers hired in 1948–1958 and was close to the estimates from previous studies for the whole cohort. In the subcohort of workers hired in 1959–1982 the point estimate of ERR/Gy was 3 times higher than in the subcohort 1948–1958 years of hire, but it was not statistically significant in the whole dose range. Restriction of doses up to 2 Gy allowed to get significant estimate of ERR/Gy (0.45; 95 % CI: 0.04; 0.95), which 4 times higher the estimate in the first subcohort calculated with the same restriction (0.11; 95 % CI: -0.01; 0.25). All subcohorts differences were not statistically significant and we can say about point distinctions only.

The Comparison of the Results of Ultrasound, CT and MRI in the Diagnosis of Angiomyolipoma Kidneys, Including Complicated by Development of the Syndrome Wunderlich

Purpose: Analysis the effectiveness of various methods of radiation studies for the detection of renal angiomyolipomas (RAMLs), including the diagnosis of Wunderlich syndrome. Material and methods: The analysis of the results of a comprehensive radiation study of the kidneys of 115 patients who were diagnosed with focal formation in primary renal ultrasound was carried out. Further, of those 115 people, 47 patients underwent MRI of the kidneys, 60 patients – CT and 8 patients complex MRI+CT, including contrast-enhanced vasculature. Results and discussion: Angiomyolipoma was detected by ultrasound in 38 (33.0 %) of 115 patients, and according to MRI and CT in total in 27 (23.5 %) patients. Coincidence of ultrasound findings and MRI and CT results was in 18 patients. Consequently, the sensitivity of ultrasound in the diagnosis of RAML was compared with MRI – 45 %; when compared with CT – 42.8 %, and specificity – 55 % and 57.1 %, respectively. Reliable signs of RAML in ultrasound were hyperechogenic homogeneous structure, clear smooth contours of the formation. The rounded form of education is statistically unreliable. Statistically significant characteristics of RAML in magnetic resonance imaging are heterogeneous structure, heterogeneous hyperintense MR-signal on T1 and heterogeneously hypointensity on T2-weighted images, always uniformly hypo-Fs for T1 / T2 Fs, with hypo clear boundary between education and renal parenchyma on T1 in the opp phase. Reliable signs of RAML with CT are non-uniform structure of education, with non-uniform x-ray density. Conclusion: Ultrasound diagnosis is necessary for screening kidney disease, while CT and MRI have greater sensitivity and specificity to determine the nature of focal formation. With the development of Wunderlich’s syndrome, a complex of radiological methods, including ultrasound, MRI and CT, allows to diagnose the cause of hemorrhage, as well as to obtain complete diagnostic information necessary for the surgeon to plan treatment.

Radiation Safety in Nuclear Medicine: Report II. Normative Documents

The specifics of improving current regulatory acts on nuclear medicine under the conditions of the "regulatory guillotine" are considered. The current state of regulatory documentation on ensuring the radiation safety of patients, personnel, individuals from the population and the environment, as well as on assessing working conditions and pension provision for personnel of domestic nuclear medicine units, is analyzed. The presence of a large number of provisions that are scientifically unsubstantiated and inconsistent with international recommendations and many years of nuclear medicine practice is shown. A number of proposals have been developed to introduce appropriate amendments to regulatory documents intended for practical use after the end of the “regulatory guillotine”.