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Identification, prevention and response to events in medical exposure are an integral part of the radiation safety system in medicine. The existing approaches in the Russian Federation, presented in the current regulatory and methodological documents, need to be updated and harmonised with international practice. At the same time, it is advisable to focus on events related with patients, because of potential overexposure of workers and public is presented comprehensively. The study presents suggestions for amendments to terminology in medical exposure events of patients and development of classification of the events criteria as well. Schemes to identify and respond to events in medical exposure that related to overexposure of patients are defined. It is advisable to implement the results of the study into the section on radiation safety in medical exposure in the updated version of OSPORB-99/2010.

Sources of ionizing radiation are an integral part of modern healthcare and are widely used for diagnostic and therapeutic purposes. One of the key aspects of the safe use of ionizing radiation in medicine is the competence of medical professionals in the field of radiation protection. The aim of this study is to investigate the level of awareness and understanding of radiation protection among interventional radiologists in the Russian Federation. The research was conducted through an online survey. The link to the questionnaire was shared in communities of interventional radiologists in social networks. A total of 78 interventional radiologists participated in the survey. The questionnaire consisted of 26 questions, 11 of which focused on assessing knowledge of radiation protection. Each question addressed a fundamental aspect essential for understanding and application in medical practice. None of the respondents answered all radiation protection questions correctly. The average score among all participants was 6.1 out of a maximum of 11. The level of knowledge did not significantly depend on years of professional experience (p>0,05). The most challenging questions concerned the biological effects of ionizing radiation. Most participants assessed their knowledge of radiation safety as satisfactory (46,1%) or good (33,3%). Self-assessment of knowledge levels also did not significantly depend on professional experience (p>0,05). As preferred sources of information on radiation safety, interventional radiologists identified online resources, scientific conferences, educational materials, and training courses. Currently, no regularly updated, unified information online resource in Russian is available. Developing such a resource represents the most cost-effective approach to ensuring and improving the awareness of interventional radiologists regarding radiation protection. Simultaneously, efforts should be directed toward enhancing the quality of training courses on radiation protection.

Today in the Russian Federation, the existing method for assessing patients` effective doses during computed tomography in the form of conversion coefficients from the dose-length product provides for the area from the head to the upper third of the femur but does not consider the possibility of scanning the whole body including the lower extremities. In this case, for some nosologies, the lower extremities may be involved. The aim of the study was to develop conversion coefficients from the dose-length product to the effective dose for whole-body computed tomography scanning including the patient's lower extremities. The coefficients for whole-body computed tomography scans (including the lower extremities) were determined for a sample of computed tomography scanners that are part of positron emission tomography combined with computed tomography devices of different models for adults and children of different age groups. In NCICT 3.0 software absorbed organ doses were calculated taking into account the specific model of devices and scan length. Effective doses were determined in accordance with the methodology presented in Publication 60 of the International Commission on Radiological Protection and Radiation Safety Standards 99/2009. Separately, conversion coefficients were developed from the dose-length product to the absorbed dose in uterus to enable predictive assessment of doses in the fetus in pregnant women. The study presents the average values of the received effective doses, absorbed doses in uterus and conversion coefficients for all considered models of devices. Conversion coefficients for protocols with automatic tube current modulation were lower compared to those for protocols without automatic tube current modulation, especially for pediatric patients: for children with an average age of 0 years – 9 times, for children an average age of 1 year – 6 times, for children an average age of 5 years – 5 times, for children an average age of 10 years – 3 times, for children an average age of 15 years – 2 times; for adults the difference was 20%. Comparison of the conversion coefficients from the dose-length product to the effective dose for computed tomographic scanning of the whole body area limited to the upper third of the femur, presented in guidelines 2.6.1.3584-19, with the values obtained in this study for the whole body area with the lower extremities without automatic tube current modulation showed that for all age groups, with the exception of newborns, the conversion coefficients for the scanning area with the lower extremities are lower than those presented in the guidelines. Using the conversion coefficients from the Guideline 2.6.1.3584-19 for whole-body computed tomography scanning with the lower extremities will lead to a significant overestimation of patient doses. The calculated conversion coefficients from the dose-length product to the absorbed dose in uterus and from the dose-length product to the effective dose for computed tomography examination of the whole body with the lower extremities for different age groups of patients are suitable for assessing the effective doses of patients and for prognostic estimates of absorbed dose in the fetus in pregnant women.

Computed tomography has become increasingly common for diagnosing socially significant diseases in recent years. In foreign practice, screening schemes for lung cancer in people belonging to risk categories have been developed and implemented. These schemes have been successfully used over the past 10 years. In this case, “low-dose” scanning protocols are used, which make it possible to perform examination with patient effective dose several times lower compared to standard protocols. Lung cancer screening methods using low-dose computed tomography are beginning to be introduced in the Russian Federation. To ensure the radiation safety of those individuals eligible for inclusion in screening programs or participating in biomedical research testing lung cancer screening, it is necessary to evaluate effective doses from low-dose computed tomography and compare these doses to established radiation dose limits. This study assessed the patients’ effective doses who underwent different types of low-dose computed tomography of chest at two medical organizations. The results of the study show that it is possible to achieve non-exceedance of the current annual effective dose limit of 1 mSv only for patients weighing less than 90 kg. For patients with higher body weight, the minimum effective dose will be in the range of 1.2 – 1.4 mSv. The results of the study indicate the need to make changes to the current regulatory and methodological documents of Rospotrebnadzor to ensure the possibility of using low-dose computed tomography as part of screening for all categories of people.

Biological excretion from patients (urine) generated during radionuclide diagnostics enters directly into the hospital sewage system. The establishment of new clearance level according to Resolution of the Government of the Russian Federation No. 1069 of October 19, 2012 may entail amendments to regulatory documents for radionuclide diagnostics departments. One of these requirements is a mandatory dedicated sewage system. Establishment of the requirement may lead to an increase the cost of the radionuclide diagnostic examinations, and to a decrease the accessibility of radionuclide diagnostic. The aim of this study was to estimate the activity of radionuclides in patient urine after radionuclide diagnostic and activity concentration in sewage water in the hospital and in the transport tank of toilet for evaluation of paths of waste manage. Based on published literature data, models of biological excretion were constructed for the following radiopharmaceuticals: 99mTc-pyrophosphate, 64Cu-Labeled Monoclonal Antibody, 18F-FDG, 68Ga-PSMA-617. The activity of radionuclides in the patient waste in the hospital and in public transport during the patient transportation to home was calculated. Various scenarios of patient transportation were considered. The values of the excreted activity, activity concentration and dose rate at 1 m from the tank with sewage water for each type of transport were calculated. The calculated values of the radionuclide activity concentration in sewage water in transport tank of toilet for the majority scenarios exceed the clearance level (up to 180 times for 68Ga-PSMA-617 when traveling by bus). According the regulatory requirements, it is necessary to collect patient excretions after radionuclide diagnostic examinations and hold it for decay. However, estimated effective doses of individuals from the public from contact with biological patient waste do not exceed the acceptable value. This is due to the short half-life of diagnostic radionuclides. The paths of management system of biological patient waste were proposed.

Radiation events (accidents) appearance is an integral part of the use of ionizing radiation sources in medicine in general and nuclear medicine in particular. To minimize the negative impact on patients, workers, and public due to such events, it is necessary to have reliable information about real prevalence of the radiation events (accidents). The current work presents the analysis of the radiation accidents with medical ionizing radiation sources registered in the “Data bank of radiation accidents and incidents” of the Rospotrebnadzor Information and Analytical Centre for Radiation Safety and the results of workers questionnaires conducted in 25 nuclear medicine departments (about 30% of all nuclear medicine departments in the Russian Federation). The results of the analysis showed that the most common registered radiation accidents in the “Data bank of radiation accidents and incidents” are identification of passengers with high external dose rate as well as identification of waste contaminated by medical radionuclides. The results of the questionnaire showed that the most common radiation accidents (events) in nuclear medicine are contamination of work clothes or work surfaces with radionuclides, or patient fluids containing radionuclides; conducting examination without proper referral; extravasation of radiopharmaceutical. Existing systems of identification and registration of radiation accidents do not allow to identify radiation events (accidents) specific to nuclear medicine. The further research aimed at developing a classification of radiation events (accidents) in medicine and methods for responding to such events are feasible.

Diagnostic reference levels are one of the effective tools for optimizing patient radiation doses in diagnostic radiology. The staff of domestic radiology departments does not have an understanding of the development process and use of diagnostic reference levels during X-ray examinations, although this tool is a generally accepted in practice abroad. The article shows the experience of forming regional diagnostic reference levels based on measurements provided by the accredited testing laboratory of the Scientific and Practical Clinical Center for Diagnostics and Telemedicine Technologies of the Moscow Healthcare Department. The diagnostic reference levels for radiography in Moscow were developed for eight of the most common types of examinations based on the operation of 216 digital X-ray machines. The resulting levels, expressed in the dose-area product (cGy-cm2) and effective dose (mSv), were compared with the local diagnostic reference levels for the Ryazan region, Russia, and national diagnostic reference levels for other countries. The analysis showed continuity in the values. Some types of studies have been optimized. The developed diagnostic reference levels are the quality performance indicators foe diagnostic radiology departments and will be used to optimize a patient radiation dose during diagnostic studies in Moscow.

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 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.

Medical diagnostics procedures involving the use of ionising radiation is one of the most intensively developing areas in medical diagnostics. At the same time, medical exposure of patients has a number of fundamental differences from other routine situations of planned exposure. As a rule, medical exposure is acute, and radiation doses in some types of examinations exceed the level of natural and man-made exposure associated with normal operation of radiation facilities. In such a situation, risk differentiation is of great importance, taking into account the different radiosensitivity of individual sex and age groups of patients. Radiation risks should be taken into account both when prescribing examinations involving the use of ionising radiation and when analysing the benefit-harm ratio associated with their application to specific patients. Another reason why risk assessment is an urgent task is the need to inform patients and/or their legal representatives about the health risks associated with the carrying out of examinations, including radiation risks. Within the framework of the present work, the risks associated with fluoroscopic examinations were assessed. To characterise the risk we used the DALY indicator, which is more and more frequently used in risk assessment, reflecting the possible number of lost years of healthy life as a result of radiation exposure during the study. The aim of the work was to calculate DALY values for different sex and age groups of patients from the Russian population during fluoroscopic examinations. To achieve this aim, the method of estimating the number of healthy life years lost due to exposure to ionising radiation, which was developed in the course of the research work, was used. The paper presents the results of calculating DALY values for three types of fluoroscopic examinations. This work represents the next step in the direction of harmonisation of radiation risk assessment methodology with the methodologies of risk assessment of other nature. One of the directions of using the calculation results is the development of methodological approaches to the calculation of sex- and age-dependent risk coefficients associated with medical exposure of patients. The analysis of the obtained results showed that the contribution of oncological diseases to the total radiation harm in older men was significantly higher than in women.

Introduction of new methods of nuclear medicine, X-ray diagnostics and therapy using medical sources of ionizing radiation inevitably leads to an increase in the number and types of accidents (abnormal situations). In international practice in recent years, special attention has been paid to the prevention of radiation accidents and incidents from medical exposure. The main focus is put on accidental exposure (overexposure) of patients in X-ray and radionuclide diagnostics and therapy. These approaches are implemented in Russian regulatory and methodological documents in a limited and formal way. The main attention is paid to large-scale technogenic radiation accidents, and accidents (abnormal situations) from medical irradiation are undeservedly ignored. The aim of the work was to analyze the terminology and classification of radiation accidents and incidents from medical exposure in the Russian Federation and foreign countries to develop proposals to improve approaches to their classification within the framework of revision of existing regulatory and methodological documents. The results of the work indicate that it is necessary to actualize Russian approaches to the definition and classification of radiation accidents in medicine considering the specifics of medical exposure. For this purpose, it is advisable to introduce different levels of accidents (abnormal situations), differing from each other by the scale of impact and consequences for patients, workers and public. Considering the absence of elaborated scenarios of accidents (abnormal situations) in Russian regulatory and methodological documents, such gradation can be borrowed from international regulatory documents provided that it is adapted to the specifics and realities of the Russian health care system

Interventional examinations are associated with high levels of patient exposure per examination, which makes it particularly important to monitor individual patient doses and to assess radiation risks. The aim of this study was the assessment of effective doses for fluoroscopy-guided balloon dilatation of benign esophageal strictures, whichwasperformedonpediatricpatientsaged 1 to 2 yearsatthe Departmentof Radiosurgical Methodsof Diagnosis and Treatment of St. Petersburg State Pediatric Medical University. Patient exposure patterns were basedonourowndatacollection. Thecalculationofeffectiveandorgandosesofpatientsnormalizedbythevalue of the dose area product measured during the study was carried out using PCXMC 2.0 software. The conversion coefficients from the dose area product to the effective dose were calculated using tissue weighting coefficients from the ICRP Publications 60 and 103 their values were 10.7 and 11.7 µSv/cGy cm2, respectively. The results of verification of the method indicated that the use of inappropriate conversion coefficients leads to an almost double underestimation of children’s effective doses. Differences in the values of conversion coefficients are significant and are explained by differences in voltage, source to image distance, and irradiation field size. A simplified model of patient exposure was proposed, which is described by a single irradiation field. The assessment of effective doses using multi-field and single-field irradiation model shows comparable results, which allows using the differentiated approach to the assessment of radiation doses of patients.

The aim of this study was to evaluate the activity of 225Ac in urine of patients undergoing radionuclide therapy with 225Ac-DOTA-TATE. Activity concentration was determined in the urine samples collected within 72 hours after injection of 225Ac-DOTA-TATE, using the ORTEC semiconductor gamma spectrometer, model TSP-DX-100T-PAC-PKG-1. Calculation of excreted activities was additionally performed based on scintig- raphy scans of patients receiving 225Ac-DOTA-TATE. Scans were conducted 5 times for each patient: immedi- ately after injection, at 4 hours, and on the 1st, 2nd, and 3rd days after injection of the radiopharmaceutical. Absolute activity values and fractions of the injected activity were calculated based on the specific activity values. The results of the calculated activity concentration values demonstrate that maximum excretion was observed within the four hours after 225Ac-DOTA-TATE injection. Significant differences between the two methods of determining 225Ac activity were observed only on the third day after radiopharmaceutical injection, which allows for the simplification of future experimental work by using indirect radioactivity measurement methods for activity calculations. There were no significant differences between patient groups with different number of 225Ac-DOTA-TATE injection, which allows for the exclusion of this parameter in the evaluation of experimental results. The results of this study represent the first published experimental data on the determi- nation of actinium excretion in patients.

There is a well-established opinion that the radiation safety of the patient and staff lies within the scope of the activities and responsibilities of the radiation diagnostics departments. However, repeated referrals and unjustified X-ray examinations from clinicians can make a significant contribution to the radiation load of the patient and the workload of the staff. The radiation safety requirements formulated in the article are designed for an effective monitoring tool for unjustified studies – the Clinical Decision Support System. The modern park of domestic software in this area was also analyzed. It was found, that the existing domestic Clinical Decision Support Systems do not fully meet the formulated current radiation safety requirements. The majority of clinical decision support system do not offer a choice of the most sparing methods of X-ray examinations (only 31% offer), and do not contain information about the accumulated patient dose for making a decision on the appointment of studies (only 23% contain). The developed methodology for assessing the Clinical Decision Support Systems will allow choosing and implementing the most optimal system in terms of radiation safety into clinical practice.

The development of nuclear medicine and, in particular, radionuclide diagnostics in the Russian Federation and the introduction of new technologies causes the necessity of the development and actualizing of the methods of the radionuclide diagnostics optimisation. Patient radiation protection optimisation through the equipment quality control and calibration is necessary to minimize the patient exposure levels and to obtain accurate and reproducible results of the uptake activity evaluation and high-quality image. However, in the national practice, conducting the equipment quality control and calibration is difficult due the lack of the requirements and methodology for quality control. The aim of the current study is the determination of the list of the necessary equipment quality control and calibration procedures in the radionuclide diagnostics department which will be harmonized between national and foreign standards and guidelines. The analysis of the national and the foreign documents standardized and recommended the gamma-camera and single photon emission computed tomography quality control and calibration procedures was performed in the study. The analysis demonstrated the national standards do not involve the frequency of the quality control for the most parameters. However, the methodology in the national standards is completely described, meets with foreign methodology and can be interchangeable, and can be used for quality control. Based on the analysis the list of the gamma camera and single photon emission computed tomography quality control and calibration procedures with recommended frequency, which is necessary for patient radiation protection optimisation and achievement of the accurate diagnostic results, are presented in the study.

adiation risks assessment in medical exposure of patients is one of the mandatory steps in justifying the medical radiological examinations. The main objectives of such assessment are the need for benefit-harm analysis, when prescribing a study, and informing patients or their legal representatives about the radiation risk associated with the recommended examination. The traditional approach to radiation risk assessment is the use of measures based on lifetime morbidity and/or mortality due to radiation exposure in risk characterization. However, the development of the methodology of population health assessment and the need to harmonize the methodology of radiation risk assessment with risks from exposure to factors of other nature imply the use of more informative generalized health indicators in the assessment of exposure to harmful environmental factors. The aim of actual work was to apply the developed methodology of radiation detriment assessment to characterize the risk by calculating DALY (number of years of healthy full life lost due to exposure to ionizing radiation) values for different sex and age groups of Russian patients undergoing computed tomography. To achieve this goal, the previously developed method of estimating the number of years of healthy life lost due to exposure to ionizing radiation was used. Calculations were performed with the use of a specially developed computer program based on the models of the International Commission on Radiological Protection using medical and demographic data of Russian population. The article presents the results of DALY calculation for six types of computed tomographic examinations. The use of DALY to characterize risk instead of the most widely used value of radiation detriment (or lifetime risk of death, relating the harm from the reduction in the quality of life in the case of non-fatal oncological disease) is an attempt to harmonize the methodology of radiation risk assessment with the methodologies of other kind of health risks. One of the directions of calculation results usage is the development of sexand age-dependent risk coefficients associated with medical exposure of patients. The analysis of the obtained results showed that the age distribution of risks agrees well with the data presented in the methodological recommendations MR 2.6.1.0215-20 “Assessment of radiation risk to patients in radiology examinations”. It is also shown that the DALY indicator can serve as a basis for comparative assessment of obtainable and avoidable risks in the field of medical radiation exposure of patients.

The article presents the analysis of the structure of computed tomography diagnostics according to the forms of the federal state statistical observation (radiation-hygienic passports in 2011–2021, forms № 3-DOZ in 2011-2021 and forms № 30 in 2014–2020) in order to assess the status of CT diagnostics in the Russian Federation and identify the main trends in the development of this type of radiation diagnostics and patient doses. In 2011–2021, there was a sharp development of CT diagnostics in the Russian Federation – an increase in the number of CT examinations per 1000 people (up to a factor of 5.9 – from 32 CT examinations per 1000 people to 189 CT examinations per 1000 people) and the contribution of CT in the collective dose from medical diagnostic exposure (3 times from 26% to 77%). The number of CT examinations per 1 CT device from 2014 to 2019 increased by 2 thousand (52%), and in 2020 by another 1.85 thousand (32% compared to 2019) and reached 7.7 thousand. The increase in the number of CT examinations was mainly due to the increased use of CT equipment. The main contribution to the structure and collective dose of computed tomography in 2021 is made by examinations of chest (58%/65%), abdomen (8%/14%), pelvis and hips (3%/4%), skull and maxillofacial area (18%/7%). In 2011-2021 for chest CT examinations, the average effective dose was in the range from 4.2 to 5.9 mSv per examination, for abdomen – from 6.5 to 9.2 mSv, for pelvis and hips – 5 to 6.7 mSv, for skull and maxillofacial area – 1.5 to 2.4 mSv. The COVID-19 pandemic in 2020-2021 caused a change in the structure of CT examinations and collective dose in the Russian Federation – the chest CT examinations occupied the first place of the contribution to the number of examinations and the collective dose. The number of CT examinations per 1000 people and the contribution of CT to the collective dose from medical diagnostic exposure in the Russian Federation were significantly lower than those in foreign countries (up to a factor of 3.5 in the number of CT examinations per 1000 people and up to a factor of 1.6 of the contribution of CT to the collective dose).

Current patient release criteria established in NRB-99/2009 relate to four radionuclides used in Russia that period of the document preparation. These criteria were calculated only considering the radionuclide decay. Thus, these criteria give conservative assessments which require the patient to stay in dedicated protected room (“hot” room) of the radiotherapy department for several days and do not allow to radionuclide therapy to be given in the outpatient hospital which certainly reduces the availability of this type of treatment. Consideration of the biological excretion of the radiopharmaceutical will be able to make the patient release criteria after radionuclide therapy significantly softer. Recently, new promising radionuclides and radiopharmaceuticals for therapy have appeared, the introduction of which into medical practice is obstructed by the lack of the patient release criteria. Current study is devoted to justification of improvement the approach to definition of patient release criteria after radionuclide therapy with promising and applied radiopharmaceuticals considering biological excretion of radiopharmaceutical. As examples, calculations of patient release criteria were performed for 177Lu-PSMA, 177Lu-DOTA-TATE, 131I-mIBG и Na131I. The dosimetric model used for calculation is based on the model which was used for definition of the current patient release criteria in NRB-99/2009. Additionally, the biological excretion of the radionuclide in radiopharmaceutical, which was assessed according to the published data, was considered. Two phases of biological excretion were evaluated for considered radiopharmaceuticals (fast and slow fractions). The main contribution of the radionuclide decrease in the patient’s body during the first hours after the injection is made by the fast-eliminated fraction. During 4-6 hours after the administration about 50% of these radiopharmaceuticals eliminated via urine. The calculation of patient release criteria were performed for slow-elimination fractions which characterize the decrease of radionuclide activity in the body after the patient release. The following effective half-lives were used: 177Lu-PSMA – 60 hours, 177Lu-DOTA-TATE – 100 hours, 131I-mIBG – 45 hours, Na131I – 7.5 days. The calculations demonstrate when planning a course of radionuclide therapy with four administrations of 177Lu-PSMA, the release of a patient is allowed at the dose rate of 20 μSv/h from the patient at the distance of 1 m; in case of radionuclide therapy with 177Lu-DOTA-TATE, release of a patient is allowed at the dose rate of 12 μSv/h. Considering the fast-eliminated fraction in the first hours after the administration, it can be assumed that more patients with normal renal function can undergo radionuclide therapy with 177Lu-PSMA in the outpatient hospital. Some patients after the 177Lu-PSMA administration and patients in the therapy with 177Lu-DOTA-TATE may be held in the department in the “hot” rooms for 1-2 days until the dose rate decrease to the acceptable levels. The consideration of biological excretion of radiopharmaceutical makes it possible to soften patient release criterion for 131I-mIBG by four times and for Na131I – by 10%. It will allow to release patients after radionuclide therapy earlier without reduce of radiation safety of people around the patient and will increase the capacity of radionuclide therapy department.

Analysis of levels of exposure of public of the Russian Federation by sources of ionizing exposure is one of main parts of the activities conducted by the Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing. Data on the doses of public of the Russian Federation from medical exposure on facility, regional and federal levels is collected using the form of federal governmental statistical surveillance № 3-DOZ “Data on patient doses from medical X-ray examinations”, that is active since 2000. For the last 20 years there were no significant updates of the form № 3-DOZ. According to the decision of the Board of the Rospotrebnadzor from 11.09.2020, a complex program on update and modernization of form № 3-DOZ was initiated, that has resulted in the approvement of new form № 3-DOZ by the order of Rosstat № 880. The form has been significantly changed to reflect the modern condition of X-ray diagnostics in the Russian Federation. The aim of the current study was to analyze main components of medical exposure dose data collection system that required update and modernization. The study was performed based on the results of assessment of the forms № 3-DOZ from different medical facilities and regions in 2015-2020. The results of the study allowed developing main approaches to the update of the form № 3-DOZ that were implemented in a new edition of the form.

The federal forms of statistical reporting (3-DOZ form, form No. 30 of the Ministry of Health of the Russian Federation and radiation-hygienic passports of the subjects of the Russian Federation for 2015–2020) were analyzed in order to estimate the current status of nuclear medicine and assess the perspective and developing proposals for improving the national system of radiation protection in nuclear medicine. Over the past six years, the number of radionuclide examinations in the Russian Federation has been at the same level: on average 530 thousand per year. In 2020 the number of examinations decreased that was caused by the epidemic of coronavirus infection. The largest number of examinations in 2015-2020 were performed in Moscow (21%) and St. Petersburg (11%). Federal medical centers equipped with high-tech equipment are located in these cities, and patients from different regions are examined in these centers. The examination of bone is the most common examination in Russia: 40% from all of nuclear medicine examination; there is a moderate increase of that examinations. There is a high number of renal examinations (17%). The next most frequent are examinations of myocardium, thyroid, liver and lungs; the number of these examinations are decrease. Due to the development of modern diagnostic technologies, installation of new positron emission tomography departments and replacement of the old equipment with the new one (decrease in the number of renographs and increase the number of positron emission tomographs), the number of “other” examinations are increased with a factor of 3.7 since 2015 but the number of “functional” examinations is decreased. About two thousand studies per year were examined on a scanner (renograph, gamma camera, single-photon emission tomography), and about 0.6 thousand hybrid imaging examinations per year were performed on a single-photon emission tomography combined with computed tomography. The annual collective dose of radionuclide diagnosis in the country has increased from 1.2 to 3.7 thousand man-Sv since 2015. The main contribution to the collective dose in Russia was associated with “other” examinations, which include hybrid imaging and whole body positron emission tomography: 55% (39% in St. Petersburg, 60% in Moscow). Due to the limitations and heterogeneous content of the federal forms of statistical reporting it is difficult to assess the current state of nuclear medicine in the Russian Federation. The authors of the study were updated of the data collection system in the radionuclide diagnosis in 3-DOZ forms; it is under approval. For detailed and reliable assessment of the nuclear medicine in the country, it is necessary to conduct a separate survey to determine the types of nuclear medicine examinations, the gender and age profile of patients and patient doses. That survey should be conducted in St. Petersburg or Moscow, as model subjects of the Russian Federation.

The development of nuclear medicine technologies in the Russian Federation contributes to the implementation of new diagnostic radiopharmaceuticals in practice. Theranostic pairs such as antibodies and peptides labeled diagnostic and therapeutic radionuclides are beginning to be commonly used. The use of radionuclides with a longer half-life in radionuclide diagnostics causes the updating of the approaches to management of liquid waste generated as a result of the patient’s metabolic activity during the time spent in the radionuclide diagnostics department. Management of liquid radioactive waste in radionuclide diagnostic department is regulated by guidelines MU 2.6.1.1892-04. The guidelines are not the regulatory document. These were developed about 20 years ago, and do not considering features of the modern methods in radionuclide diagnostics, promising radionuclides with half-life of several days, and new criteria for classifying as a radionuclide waste in accordance with Resolution of the Government of the Russian Federation No. 1069. The aim of the study was the assessment of the radionuclide activities excreted from patient after radiopharmaceutical injection in radionuclide diagnostics departments in order to define the waste management pathways. In a result, all diagnostic and therapeutic radiopharmaceuticals were divided into the categories: radiopharmaceuticals with ultrashort-lived radionuclides, which can be discharged into the hospital sewerage without any restrictions; radiopharmaceuticals with 131I, which need the special sewerage; the other radiopharmaceuticals, which need to assess the volume of discharged radionuclide activities during the projection of the nuclear medicine department. The method of assessment of the radionuclide activities entering the hospital sewerage is presented.

This study is focused on the description of management of data on the exposure of the Russian population for the State report on the evaluation of sanitary-epidemiological well-being of public in the Russian Federation, that was presented by the Federal service of surveillance on consumer rights protection and human wellbeing. It is shown that the mains sources of data on the radiation situation and public exposure are system of social-hygienic monitoring, Joint state system of control and accounting of public doses; and radiationhygienic passportization, functioning under the control of Rospotrebnadzor facilities.

Computed tomography has become the main method of early diagnostics of COVID-19 during the pandemic of the novel coronavirus infection. Based on results of computed tomography of the chest it is possible to diagnose viral pneumonia associated with COVIS-19, to quickly assess the lung damage volume and severity of changes, to perform quick routing of patients and to start antiviral treatment. Hence, 2020 was associated with a rapid increase in the number of computed tomography examinations with corresponding changes in the structure of X-ray diagnostics. The aim of the current study was to evaluate the impact of the pandemic of the novel coronavirus infection on the structure of X-ray diagnostics and collective doses from medical exposure in the Russian Federation in 2019-2020. The study was based on the results of analysis of the federal state statistical surveillance forms №3-DOZ and №30 as well as on the data on Covid-19 morbidity in the regions of the Russian Federation. The results of the study indicate that there were no significant changes in the structure of X-ray diagnostics in 2020 compared to 2019 except for the increase in the number of computed tomography examinations. Their contribution to the total number of X-ray examinations has increased to 8,2% in 2020 compared to 4,6% in 2019. Contribution of other imaging modalities to the total number of X-ray examinations has not changed significantly. In 2020 the number of X-ray examinations decreased by 20% in average, varying from 6% for diagnostic nuclear medicine to 42% for interventional examinations. At the same time, the number of computed tomography examinations has rapidly increased by 60%. The structure of collective dose from medical exposure has significantly changed in 2020. Contribution of computed tomography to the collective dose in 2020 accounted for to 74% compared to 57% in 2019. Contribution of other imaging modalities has decreased by the factor of 1,5-2. Contribution of radiography examinations has decreased to 10,5% compared to 19% in 2019. Collective doses have correspondingly decreased by 20-30% for all imaging modalities except for computed tomography. Collective dose from computed tomography has increased by 71% compared to 2019. The number of all X-ray examinations in the Russian Federation has decreased by 12%: from 294 million in 2019 to 258 million in 2020. Collective dose from medical exposure has rapidly increased in 2020 by 30% to 115 thousand man. -Sv compared to 88 thousand man. -Sv in 2019. In average, in regions of the Russian Federation in 2020 each second computed tomography examination has been performed as a part of COVID-19 diagnostics with 2,3 computed tomography examinations per person infected with COVID.

The aim of the search was to compare the sources of information and evaluate dynamics of changes of the patients doses during x-ray and radionuclide examinations in medical organizations in Moscow from 2017 to 2020. Material and methods: Reporting forms № 3-DOZ, № 30 and Radiation-Hygienic Passport for 2017–2020 from Moscow organizations of different forms of ownership were collected and analyzed. The analysis was performed of the main indicators that determine the radiation safety in medical exposure: the number of medical organizations operating sources of ionizing radiation, the equipment of radiation diagnostics, the structure of radiation diagnostics and collective doses from medical exposure. Results: The analysis of trends of the development of radiation diagnostics in Moscow presented in the paper shows that the number of organizations operating ionizing radiation sources is increasing every year; the number of computed tomography scanners is growing by an average of 10% per year, and there is approximately the same increase in the number of computed tomography examinations. Therefore, in 2017-2019 the annual increase in the number of examinations was 10%; it was 30% in 2019–2020, which is associated with the epidemic of the new coronavirus infection COVID-19. The increase in the collective dose from medical exposure corresponds to the increase in the number of X-ray examinations. Comparison of the considered reporting forms and data from the unified X-ray information system shows that all reporting forms have their advantages and disadvantages, which are discussed in detail in the paper. For a comprehensive assessment of the condition of radiation diagnostics, it is necessary to compile data from different statistical reporting forms, which negatively affects the reliability and representativeness of the data. It should be noted that all the considered statistical reporting forms provide no data on individual and accumulated patients doses, as well as standard (typical) doses for the equipment of X-ray and radionuclide diagnostics. The existing procedure of data collection does not allow to receive and analyze the data online. Conclusion: Among the analyzed statistical reporting forms, there is no one that fully provides the tasks of the current assessment of the situation and operational management of public radiation doses. Some of the data in fact duplicate each other, and the existing discrepancies are more likely express difficulties in collecting and summarizing information than differences in reporting forms. Current statistical reporting forms require revision, consolidation, clarification and automation of data collection processes. Further implementation of electronic systems for recording and controlling patients doses, and generation monitoring and reporting systems, as well as interdepartmental interaction systems and the creation of an electronic office of organizations will reduce the rate of non-submission of reporting documentation. That makes it more objective and provides all the data necessary to optimize radiation protection of patients.

Radioactive waste management is a modern-day issue in terms of radiation safety due to the development of radionuclide therapy, the emergence of new radiopharmaceuticals, radionuclides, and treatment methods, which allow for radionuclide therapy in a day hospital. According to the current domestic regulatory and methodological support biological wastes generated during the patient’s metabolic activity after injection of the radiopharmaceuticals for the therapy refer to the liquid radioactive waste. These wastes must be collected and kept for decay in hospitals to the safe levels before being spilled into the municipal sewerage. It requires additional expenses to the hospital for making the special sewerage. To increase the availability of radionuclide therapy, it is necessary to update the requirements of the liquid radioactive waste management in nuclear medicine departments, considering the volume activities of different diagnostic and therapeutic radionuclides in wastes generated after the injection of radiopharmaceuticals to the patients. On the basis of findings, it is possible to evaluate the feasibility of the binding requirement for the availability of special sewerage in the departments of the radionuclide therapy. In this work, excretion of the radiopharmaceuticals used in therapy: 89Sr-dichloride, 223Ra-dichloride, 131I-MIBG, 177Lu-PSMA, and 225Ac-PSMA was studied based on published data to determine the activity levels of radionuclides in waste of patients. As a results of preliminary computations, some nuclear medicine procedure will not lead to generation of liquid radioactive waste from biological waste of patients in sewerage system in usual operating condition and special sewerage is not strictly necessary. For example, estimations of radionuclide activity in wastes showed the volume of current sewerage system in a small hospital with a limitation of 50 beds can be enough to reduce the level of specific activity of radionuclides in wastewater from one patient a day after radionuclide therapy with 89Sr-chloride and 223Ra-dichloride. In order to revision of requirements to special sewerage in each department of radionuclide therapy and to development of differentiated approach to the management of biological waste of patient in nuclear medicine departments, which ensure environment protection and radiation safety of people, it is necessary to continue the research including development and modeling of realistic scenario of staff and patient radiation exposure confirmed experimental results.

The aim of this study was to demonstrate how the severity of radiation damage in the case of bone marrow syndrome due to acute irradiation depends on the non-uniform irradiation of the body. We used the calculation method that involves the evaluation of organism mortality as a function of bone marrow cells colony survival vs dose for different radiation profiles. It was presumed that the probability of the death for the organism is the same for the same value of survival level of the bone marrow cells regardless of the dose distribution by mass of the organ. The dose of uniform irradiation that is equivalent to the dose for the L-th case of non-uniform irradiation is calculate based on the survival level of the total marrow cells. After that the probability of the death of the organism is estimated according to the dose response curve. Dose distribution in bone marrow of computational MIRD-5-type stylized model adult man for different geometries of exposure by point source of 137Cs was evaluated. Larger non-uniformity of the dose distribution in the bone marrow at the same dose in free air in the site of human location causes a greater probability of survival due to a greater proportion of bone marrow cells that have preserved the possibility of reproduction. The values of mean 50% lethal dose for cases of approximately uniform irradiation of the body surface (point source at a distance 10m) and sharply non-uniform irradiation (point source at a distance of 0.5 m) differ approximately by the factor of 1.7 – 2.5 depending on direction of irradiation. Additionally the values of conversion coefficients from the reading of an individual dosimeter to the value of an effective dose for various geometries of irradiation of emergency workers from the 137Cs point source were calculated. The average value of the conversion coefficient from personal dose to effective dose for the considered exposure situations is 0.7 Sv Cy-1 and the 90% confidence interval is 0.49 – 0.99 Sv Gy-1.

Risk communication is one of the stages of health risk analysis and is an interactive process of exchange of information and opinions about risks, including medical risks, between risk assessment specialists, decision makers, the media, stakeholder groups and the public. In organizing interaction with stakeholders in the risk communication process, sociological research helps to explore the attitudes of the actors. One of risk communication situations in the field of radiation protection is information provision to patients and their legal representatives about radiation health risks due to the medical radiology examinations. The aim of this study was to assess the radiation risk perception among parents and legal representatives of children undergoing radiological examinations. Parents and legal representatives of children undergoing hospital treatment from November 2021 to March 2022 were interviewed in a large pediatric infectious diseases hospital. A questionnaire designed at St. Petersburg Research Institute of Radiation Hygiene was used for the interviews. In total, 125 people were interviewed. The study showed that there were no significant differences in the perception of radiation risks among parents and legal representatives of children undergoing inpatient treatment with different socio-demographic characteristics. The level of knowledge was not identified as a factor shaping a tolerant attitude toward medical radiation risks. Parents and legal representatives of children undergoing hospital treatment show high rates of trust in the attending physicians and medicine in general. The study results show that those who have been informed about the risks generally have lower risk perception for radiological medical examinations than those who have not been informed about the risks.

As a part of administrative reform and “regulatory guillotine” in Russia in 2020-2021, several significant changes in the governmental regulation of dental care have occurred: implementation of new version of Order of provision of dental care and infrastructure of governmental dental facilities; approval of Rules of carrying of X-ray examinations; development of changes in the sanitary-epidemiological requirements to medical facilities. Meanwhile, the requirements on the radiation safety in the medical facilities remained the same. The lack of coordination during the development of new documents between the Ministry of Healthcare and Rospotrebnadzor resulted in preservation of the existing problems with the use of X-ray equipment in dentistry (for example, related to the allocation of dental X-ray units in residual and public buildings) and appearance of new problems (for example, removal of a requirement for the license in radiology for dentists). The study is focused on the analysis of the issues of regulation of the provision of radiation safety for dental care of public of the Russian Federation. It includes a review of the acting regulatory documents of the Ministry of Healthcare and Rospotrebnadzor, regulating the allocation of dental X-ray units and provision of dental X-ray examinations, with subsequent identification of the major issues and problems. The results of the study indicate that changes in the regulatory documents of the Ministry of Healthcare implemented in 2020-2021 contradict the acting requirements on radiation safety. It is necessary to further improve the legislative base regulating the dental care: harmonization of the acting requirements on the equipment of the dental rooms, orders and standards of dental care, training of staff. The harmonized base should result in a provision of qualitative dental care and radiation safety.

After the publication of ICRP Publication 103 in 2007 and IAEA Basic Safety Standard “Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards. General safety requirements Part 3” in 2014, there is an ongoing process in the Russian Federation on the harmonization of the norms of the radiation safety and basic rules on the provision of the radiation safety with the international requirements. According to the Decree of the President of the Russian Federation № 585 “On the establishment of the basis of the governmental policy in the field of the provision of nuclear and radiation safety in the Russian Federation in the period up to 2025 and the future perspective” and the Plan of the execution of the “basis of the governmental policy…”, approved by the Decree of the Government of the Russian Federation №139-r, 02.02.2019, a work has been initiated on the development of the changes and additions into the Federal State Laws № 170-FZ “On the use of the nuclear energy” and № 3-FZ “On the radiation safety of the public”. For the successful execution of the mission it is necessary to develop joint inter-agency workgroups with the parallel development of the changes and additions to the № 170-FZ. №3-FZ, NRB and OSPORB.

Today, the treatment of cancer with the use of radiopharmaceuticals is a developing method all over the world. The preparation of the radiopharmaceuticals and its quality control prior to its administration to the patient is one of the important elements of nuclear medicine procedures. The instability of the compound can lead to a change in the distribution of the radionuclide in the patient’s body, a decrease in the effectiveness of treatment, as well as to unjustified irradiation of healthy organs and tissues. The aim of this work was to estimate the absorbed doses in human organs and tissues during radionuclide therapy using 225Ac for the case of the 225Ac release. The absorbed doses were calculated for the model presented in ICRP Publication 141 for healthy people. This model consists of 18 cameras (blood, cortical volume, cortical surface, cortical red bone marrow, trabecular volume, trabecular surface, trabecular red bone marrow, kidneys (two chambers), bladder, liver (two chambers), gonads, contents of the small intestine, contents of the upper large intestine, soft tissues. Time-integrated activities were calculated using the specialized software SAAM II v2.3. The calculation of absorbed doses was performed using the IDAC-Dose 2.1 software. The highest absorbed doses were obtained for liver, testes, ovaries and red bone marrow, which leads to an increase in doses in these organs in comparison with doses from 225Ac-PSMA up to a factor of two. A change in the biodistribution of 225Ac in a patient’s body, associated with the release of a radionuclide from the radiopharmaceuticals, can lead to an increase in doses in healthy radiosensitive organs and tissues, as well as to a decrease in the effectiveness of treatment.

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.

The number and contribution of high dose imaging modalities, computed tomography in particular, is rapidly increasing both in the 'Russian Federation and other developed countries. Maximal increase in the number of computed tomography examinations in Russia was observed in 2020 due to the full-scale application of this imaging modality for the diagnostics of the novel coronavirus infection COVID-19. The use of computed tomography for the examination of the chest for the pregnant women is associated with several issues. An internationally accepted approach for the provision of the radiation safety of the pregnant patients is the assessment of the absorbed dose in the fetus after each X-ray examination. However, there are no existingn approved methods for the assessment of the absorbed dose in the fetus in the Russian Federation. The aim of the current study was to assess the doses in the fetus for the pregnant women undergoing computed tomography of the chest due to the COVID-19 and to estimate the probability of the development of the deterministic effects for the fetus. The study was based on the collection of the parameter of Russian and international computed tomography protocols. Parameters of the international computed tomography protocols were collected viameta-analysis of the existing publications; Russian protocols — via data collection in computed tomography departments in St-Petersburg hospitals. Absorbed dose in the uterus of the female patient and effective dose for the fetus were calculated using NCICT 3.0 software for 8, 10, 15, 20, 25, 30, 35 and 38 weeks of pregnancy. The results of the calculations indicate the lack of significant differences between absorbed doses in the uterus and effective doses for the fetus for all stages of pregnancy. Maximal doses for the selected computed tomog­ raphy protocols were in the range of 0.5 mGy (mSv) for 8-25 weeks, 0.6 mGy (mSv) for 30 week, 1.4 mGy (mSv) for 35 week and 2.7 mGy (mSv) for 38 week. The threshold for the development of the deterministic effects equal to 100 mGy cannot be exceeded even for repeated (10-15) computed tomography chest scans. Hence, the use of computed tomography as the primary method of COVID-19 diagnostics and staging will not be associated with the development of deterministic effects in the fetus.

The aim of the study was to develop a methodology for assessing radiation risk for patients undergoing medical examinations in the Russian Federation. The methodology is based on the risk model of the ICRP Publication 103, the coefficients of lifetime radiation risk for the Russian population and the results of evaluating the doses of patients in the Russian Federation. For thirty examinations that define about 80% of the collective dose of the population of the Russian Federation from medical exposure, the radiation risk was calculated using «gold standard», — the organ doses and the corresponding sex/age risk coefficients for the Russian population. For other examinations (with the exception of mammography) the values of the risk coefficients normalized on 1 mSv of effective dose, which is the averaged value for four selected anatomical areas of the body: head, neck, chest and abdominal cavity — pelvis, were used. It is assumed that for such examinations the error of risk assessment will increase relative to the error of risk assessment for the aforementioned 30 examinations not more than 30%. It is shown that risk estimates for some examinations calculated using the “gold standard” may differ from such estimates on the base of effective dose and nominal risk coefficients averaged by age and the sex to the order of magnitude.

This paper demonstrates the shortcomings of the existing method of radiation control in the X-ray rooms and the interpretation of the results of the measurements to assess the compliance of the working conditions of various groups of exposed individuals with radiation safety requirements. A new method of interpretation of the measurement results is proposed, considering the relative time spent by certain categories of exposed persons in the corresponding rooms during the use of the X-ray units, as well as the use of personal protective equipment (lead aprons). The interpretation of the measurement results in the treatment room according to the new approach has demonstrated the compliance of the working conditions to the Norms and Rules of radiation safety, provided that the worker is wearing a protective apron. The proposed approach to the interpretation of the results of the measurements in adjacent rooms leads to both reduced and stricter requirements for the stationary shielding. The paper includes a special focus on the incorrect calculation of stationary shielding for the installation of several X-ray units in one X-ray room within the framework of the current approach.

The aim of the study was to estimate the patient effective doses from hepatic arterial chemoembolization. The study was based on the parameters of the protocols of liver chemoembolization collected for 67 patients in Angiography department of the «A.M. Granov Russian Scientific Center of Radiology and Surgical Technologies» of the Ministry of Health of the Russian Federation. The parameters were collected using a dedicated questionnaire and exported from digital image files in DICOM format with preliminary anonymization. The simulation of patient exposure was performed using PCXMC 2.0 software. The median values of the patient dose-related quantities (minimum and maximum values) were as follows: total dose–area product – 6.1 Gy×cm2 (3.4-693Gy×cm2), fluoroscopy time – 7.5 min (2.0-28.3 min), effective dose – 11.7 mSv (0.6-132 mSv). For three patients effective doses exceeded 100 mSv. In two cases, total dose-area product exceeded the control values for deterministic effects in the skin. No tissue reactions were identified for the whole patient sample.

The paper presents the data that allow calculate the attenuation factors in lead, tungsten and concrete of various thicknesses or the thickness of shielding made of these materials for a given attenuation factor for the spectra of gamma radiation of 131I and 177Lu radionuclides. Using these data the effectiveness of the protection of supporting equipment (portable containers, shielded syringes, etc.) and the possible doses of external radiation of medical personnel in the radionuclide therapy department were calculated. It is shown that there are short-term operations in the production process when a radiation source (container with a capsule with activity, syringe with activity), being near the body of a medical worker, creates a significant dose rate. For this reason the annual individual dose of external exposure of a medical worker can approach or exceed 1/3 of the dose limit. Calculation of the attenuation of 131I gamma radiation by stationary shield showed that the thickness of walls and floors made of concrete 200 – 400 mm will ensure that the permissible values of the dose rates of gamma radiation in the air do not exceed at annual turnover of activity in the radionuclide therapy department of ~ 3.3 · 1012 Bq.

To ensure the quality assurance of CT-examinations, it is necessary to obtain the high-quality diagnostic information and maintain the optimal exposure levels of patients and medical staff. This paper is focused on the requirements and main aspects of quality assurance of CT-examinations, which include quality control of the equipment, methods of CT-image quality control, optimization of radiation protection, as well as management of the unintended and accidental medical exposure. The paper contains recommendations on quality control of diagnostic equipment, methods for monitoring the quality control of CT-images, values of diagnostic reference levels for the detection of abnormally high patient doses and optimization of the radiation protection of patients, as well as the recommendations for management of radiation and non-radiation accidents. All main sections of the paper represent an unified quality assurance system in computed tomography.

Radionuclide therapy with 223Ra-dichloride is used to treat bone metastases and to improve the quality of life of patients with metastatic castration-resistant prostate cancer. At the present time there is no reliable data on the biodistribution of the 223Ra-dichloride in the patient body. The aim of this study was to assess absorbed, equivalent doses in radiosensitive organs and tissues and effective dose from internal exposure for patients with metastatic castration-resistant prostate cancer treated with 223Ra-dichloride. Internal doses from 223Ra-dichloride were calculated for a chamber model specific for patients with metastatic castration-resistant prostate cancer. This model consists of 8 chambers (blood plasma, two chambers describing bone tissue, small intestine, upper large intestine, lower large intestine, feces and the rest of the body). Time-integrated activities were calculated using the SAAM II v2.3 software. The IDAC-Dose 2.1 software was used to calculate the absorbed doses. The highest absorbed doses in organs and equivalent doses were determined for the bone surface and red bone marrow. The absorbed dose from a-radiation in the bone surface for a set of six therapeutic procedures with 223Ra-dichloride was estimated as 1 Gy; in the red bone marrow — 0.14 Gy. However, the approach used does not specifically consider accumulation of the radiopharmaceutical in metastases, which can lead to a significant overestimation of the absorbed dose in the healthy part of the bone surface and red bone marrow.

The aim of the current study was to perform a comparative assessment of the radiation and non-radiation health risks for the sample of transgenders as well as the assessment of their perception of these risks. The study was performed on the sample of patients, undergoing the gender reassignment surgery from female to male. The structure of surgical procedures and the corresponding X-ray examinations was analyzed with the subsequent assessment of the radiation and non-radiation health risks. The level of patient knowledge on the risks and benefits of the medical procedures and perception of the ratio of radiation and non-radiation risks were evaluated based on the results of the sociological study. The study included the patients that underwent gender reassignment surgery in August 2012 – February 2018 on the base of I.M. Sechenov First Moscow State Medical University. Data collection and questioning were performed in August 2019 – March 2020. Data on the structure of the surgical procedures and X-ray examinations was collected for 99 patients; 86 patients agreed to participate in the questioning. The results indicate that the selected sample of patients, undergoing the gender reassignment surgery from female to male, is a high risk group both for radiation and non-radiation factors. For the whole multi-stage gender reassignment surgery, a patient could receive a total effective dose up to 250 mSv due to repeated computed tomography scans of chest, abdomen and head with contrast, corresponding to the lifetime attributive radiation risk of up to 1×10-2. Comparison of radiation and non-radiation risks for that patient sample indicates the dominance of the risk of successful suicide attempts (5×10-2). Radiation risks are equal to or even exceed (for the final stages of the gender reassignment surgery) the other risks of mortality from the non-radiation factors (anesthesia – 5,4×10-5, thrombosis – 2×10-5, post-surgical complications – 6×10-2). The reduction of suicide risks, as a result of the treatment, outweighs all other risk factors and justifies the gender reassignment surgery. The results of a sociological study show a decrease from 77% to 23% of suicidal thoughts among the patients. The study indicates that risk-communication was performed on the unsatisfactory level: less than 40% of the patients were informed about the possible health risks during the treatment; less than 50% of respondents knew about the benefits of X-ray examinations. About 70% of the patients rate their current problems with health higher compared to the risks from diagnostics and surgery. It explains the lack of interest to the radiation risk.

High levels of tuberculosis morbidity in the Russian Federation lead to the extensive use of X-ray diagnostics for the tuberculosis screening and assessment of the effectiveness of treatment. Digital radiography and computed tomography are traditionally used for the diagnostics of tuberculosis. These methods are associated with significant drawbacks: low specificity for radiography, high costs per examination, significant patient doses, and limited availability for computed tomography. As an additional method for the assessment of the effectiveness of the tuberculosis treatment it is possible to use linear tomography performed on the digital X-ray units. The aim of the current study was to evaluate the possibility of utilization of the digital linear tomography for the control of the effectiveness of tuberculosis treatment in a dedicated antitubercular medical facility. The study was divided in two stages. The first stage was aimed at the assessment of the diagnostic image quality of the digital linear tomograms obtained using the previously developed low-dose imaging protocols. Image quality assessment was performed using an anthropomorphic chest phantom and dedicated imitators of the lung lesions. Image quality was assessed by the experts (radiologists) based on the developed image quality criteria. Results of the first stage of the study indicate that all low-dose protocols allow obtaining images with at least acceptable image quality. Hence it was possible to propose low-dose protocols for clinical evaluations. The second stage of the study was performed as a prospective cohort survey aimed at the evaluation of the structure of X-ray examinations, patient doses and clinical image quality of the digital linear tomograms in antitubercular early treatment center. The cohort survey included two patient samples, uniform by age and gender composition, anthropometric characteristics and structure of diagnosis. One of the samples was imaged using standard (vendor) digital linear protocols, other – using the proposed low-dose protocols. Dose data collection (measurement of dose-area product and subsequent calculation of effective dose) and expert image quality assessment was performed for each patient. The results of the second stage of the study indicate that the use of the low-dose protocols allow reducing the patient effective doses per examination up to a factor of 6–8 (0.56 – 5.9 mSv for standard protocols; 0.2 – 1.15 mSv for low-dose protocols) due to the reduction in tube current-time product (126 mean mAs and 11 mean mAs, respectively). The dose reduction is accompanied by the reduction in the image quality of the linear tomograms (from “excellent” or “good” for standard protocols to “acceptable” for low-dose protocols). However, that dose not hinder the conclusion decision and identification of pathologies. Results of the study indicate that digital linear tomography can be used for the evaluation of the dynamics of the pathological process in the lungs with the previously defined localization of the pathology. The presented low-dose protocols were implemented into radiological practice of the antitubercular early treatment center. Currently, the proposed low-dose protocols are under evaluation for the large-scale study on the base of general practice hospitals

The current study was aimed at the justification and proposal of the supplements and corrections that are planned for the implementation in the updated version of the Methodical guidelines “Control of the effective doses of the patients from the X-ray examinations” (MU 2.6.1.2944-11). This study included estimation and/ or update of the values of the conversion coefficients from measurable dose characteristics (entrance-surface dose, dose-area product) to the effective dose for various X-ray examinations. Estimation of the updated conversion coefficients was based both on the home analytical and experimental studies based on the modern protocols of the X-ray examinations, and the results of the published data. Updated values of the conversion coefficients were presented for: fluoroscopic examinations of the gastro-intestinal tract with barium media for adult and pediatric patients; interventional examinations of the adult patients; computed tomography examinations for adult and pediatric patients; dental intraoral examinations. For the first time, the methods of the estimation of the effective dose and corresponding conversion coefficients were presented for: computed tomography of the extremities, whole body, scan of several anatomic regions; angiographic examinations of the heart vessels of the pediatric patients of different age categories; slot-scanning X-ray examinations; bone densitometry.

According to the Decree of the President of the Russian Federation №585, 13.10.2018, the main approaches to the provision of the radiation safety of the public of the Russian Federation from the use of the sources of ionizing radiation in medicine are the harmonization of the national legislative documents with the international recommendations and the development of the new and improvement of the existing methods of the assessment of the individual patient doses and corresponding radiation risks. The current study was aimed at the justification of the complex of actions to prevent the unnecessary medical exposure of the Russian population. That required to analyze the existing national and international approaches to the assessment of the radiation risks from medical exposure and the results of the existing epidemiological studies, as well as to assess the risks from the most common and/or high dose X-ray examination (computed tomography, interventional examinations, nuclear medicine) for pediatric and adult patients. It was indicated, that these examinations correspond to the “Low” and “Moderate” radiation risk categories. The level of the lifetime radiation risk of cancer morbidity in the Russian Federation for the computed tomography was estimated as 1 case per 3-30 thousand examinations. The performed analysis of the existing international regulatory and methodical documents indicated the significant differences in the practice of the radiation protection in medicine. International practice is mainly based on the practical application of the principle of justification by using the X-ray examination referral guidelines and various methods of risk communication with patients. Main actions to reduce the patient doses and to improve the diagnostic image quality are performed on the hospital level by medical physicists in collaboration with medical staff and representatives of the vendor. It should be noted that dose limits are not applied to the exposure of healthy individuals from screening X-ray examinations. Based on the results of the comparison of the national and international practices of the radiation protection in medicine, both general and specific (for different X-ray modalities) recommendations for the improvement of the system of the radiation protection of the patients and staff were developed. These recommendations should be implemented on practice in the form of the complex program of the optimization of the radiation protection of the public of the Russian Federation from medical exposure. This program can be developed and implemented through the collaboration of the Federal Service of Surveillance on Consumer Rights Protection and Human Well-being and the Ministry of Healthcare of the Russian Federation.

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.

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.

Dose limits are commonly not applied for the radiation protection from medical exposure in the international practice; the principles of justification and optimization are used instead. However, the Russian Norms of the Radiation Safety NRB 99/2009 provide for the limitation (non-exceedance) of the doses for the healthy individuals undergoing X-ray examinations related to the employment-related, legal or screening purposes by 1 mSv per year. The aim of the study was to assess the feasibility of limiting the doses for the healthy individuals undergoing diagnostic medical X-ray examinations in the context of the revision of the Norms of the Radiation Safety. The study included the analysis of the existing Russian legislative documents regulating the medical exposure related to the employment-related, legal and screening purposes; evaluation of the imaging modalities commonly used for these purposes and conservative estimation of the effective doses per employment-related medical examination or a periodic health assessment. The results of the study indicate that a limit of 1 mSv per year is systematically exceeded for the healthy individuals undergoing X-ray examinations related to the employment-related, legal or screening purposes. Implementation of the modern screening methods (low-dose computer tomography, breast tomosynthesis) would lead to the significant increase of the effective dose per periodic health assessment up to 3-8 mSv per year. Hence, it is proposed to use the principle of the optimization with the establishment of the diagnostic reference levels for the screening X-ray examinations for the radiation protection of healthy individuals from medical exposure.

Fluoroscopic examinations of the upper gastro-intestinal tract and, especially, barium meal examinations, are commonly performed in a majority of hospitals. These examinations are associated both with substantial individual patient doses and contribution to the collective dose from medical exposure. Effective dose estimation for this type of examinations is complicated due to: 1) the necessity to simulate the moving X-ray irradiation field; 2) differences in study structure for the individual patients; 3) subjectivity of the operators; and 4) differences in the X-ray equipment. The aim of the current study was to estimate conversion coefficients from dose-area product to effective dose for barium meal examinations for the over couch and under couch exposure conditions. The study was based on data collected in the X-ray unit of the surgical department of the St-Petersburg Mariinsky hospital. A model of patient exposure during barium meal examination was developed based on the collected data on fluoroscopy protocols and adult patient irradiation geometry. Conversion coefficients were calculated using PCXMC 2.0 software. Complete examinations were converted into a set of typical fluoroscopy phases and X-ray images, specified by the examined anatomical region and the projection of patient exposure. Conversion coefficients from dose-area product to effective dose were calculated for each phase of the examination and for the complete examination. The resulting values of the conversion coefficients are comparable with published data. Variations in the absolute values of the conversion coefficients can be explained by differences in clinical protocols, models for the estimation of the effective dose and parameters of barium meal examinations. The proposed approach for estimation of effective dose considers such important features of fluoroscopic examinations as: 1) non-uniform structure of examination, 2) significant movement of the X-ray tube within a single fluoroscopic phase, and 3) the variety of exposure geometries within complete examination.

Objective: to search for the possibility of lowering a dose burden on a patient during preventive chest radiography.Material and methods. The investigation was carried out in two hospitals (City Mariinsky Hospital, Saint Petersburg, Russia) and (Skane University Hospital, Malm ° ö, Sweden) in 2013–2015. The existing protocols for this type of investigation were corrected by changing the anode voltage, the thickness of complete filtration, and the refusal to use a raster to determine the optimal dose/image quality ratio.Results. The investigation showed the possibility of reducing the values of the products of the dose per area (PDA) by 47% and lowering the effective dose (ED) by 33%, by increasing the tube voltage (up to 125 or 150 kV) and decreasing the thickness of full filtration of direct beam radiation (to 3 mm Al). The refusal to use a raster could further reduce the value of PDA and ED to 75%.Conclusion. Comparison of the dose values of Russian and Swedish X-ray apparatuses showed that the absolute values of PDP and ED are 10 times lower for Swedish devices in the same modes of chest radiography. This fact can be explained by the use of various image receivers and automatic exposure control settings.

Diagnostic reference levels are the main and the most effective tools of optimization of the radiation protection of patients from medical exposure. Diagnostic reference levels should be established based on the results of dedicated dose surveys, allowing evaluating typical patient dose distributions in a selected dose quantity for the selected X-ray examinations. The aim of the current study was to assess the distributions of typical effective doses in representative Russian regions. Materials and methods: Typical patient effective doses for the 13 most common radiographic X-ray examinations were collected in 203 X-ray rooms in 101 hospitals in six regions of Russian Federation in 2009–2014. A differentiated approach was used for the estimation of the typical effective doses depending on the image acquisition technology. Effective doses were estimated using «EDEREX» (Russia) computational software. Results and discussion: Results of the dose data analysis indicate the lack of significant differences between the distributions of the typical effective doses between the selected regions, allowing merging the regional samples and further evaluating the pooled (joint) sample. A significant ratio of maximum to minimum (up to two orders of magnitude) due to a presence of X-ray units with abnormally high and low typical effective doses was observed for all 13 selected X-ray examinations. Abnormally high typical effective doses can be explained by performing the examinations using high values of tube current-time product (150–600 mAs) on a maximum field size (up 40×40 cm). Removal of the typical effective doses below 5%-percentile and above 95%-percentile of typical effective dose distributions for all examinations would result in a reduction of a mean effective dose by up to 30% and reduction of a 75%-percentile of the distributions by up to 15%. No significant differences between the distributions of TED for analogue and digital X-ray units were observed for the pooled sample for selected examinations except for the examination of the chest in posterior-anterior projection. Conclusions: These results should be considered in the process of establishing and implementing DRLs as well as in the cost-benefit analysis of the optimization in radiography.

The modern approach to the radiation protection of the patients from medical exposure is mainly based on the principle of optimization using diagnostic reference levels. Implementation of diagnostic reference levels and optimization in Russian radiological practice is limited due to lack of methodology of data collection and patient dose assessment, investigation and management of abnormally high and low patient doses. Current study is focused on the justification of the diagnostic reference levels concept and practical aspects of establishment of diagnostic reference levels for common radiographic X-ray examinations and their use in clinical practice. It is proposed to establish diagnostic reference levels as the 75%-percentiles of X-ray unit distributionby the patient standard doses for a given X-ray examination. Methodology for standard doses assessment is presented for different types of X-ray units. Based on the results of dose data collection in different regions of the Russian Federation in 2009–2014, the national diagnostic reference levels values are estimated in terms of effective dose for the radiographic examinations of skull, chest, cervical, thoracic and lumbar spine,abdomen and pelvis. The methodology of the optimization process is developed for the hospital use. It includes a comparison of the patient standard doses with the national diagnostic reference levels, investigation and correction of abnormally high and low patient doses. A list of corrective measures is proposed: from additional training of the staff and manual adjustment of the parameters of examinations to the replacement of an X-ray unit. It is conferment that even a limited implementation of the optimization methodology would allow to reduce standard doses with a factor of 1,5.

Saint-Petersburg Institute of Radiation Hygiene has undertaken in 2009-2010 selective regional study of exposure levels of adult patients during radiological diagnostic procedures in 20 hospitals of the city Saint-Petersburg and the Leningrad region. We examined 52 X-ray machines, 14 computed tomography rooms and 9 angiography rooms. The average effective doses, depending on the technology and type of patient examination, varied within the following limits: routine radiographic procedures - from 0.05 mSv to 0.6 mSv, computed tomography procedures - from 0.6 to 17.5 mSv, interventional examinations - from 6 to 60 mSv. The obtained effective doses of the patients in the studied hospitals of Sant-Petersburg and Leningrad region are compared with the average values recommended in the statistical form 3-DOS, and with published foreign data.