This article is aimed at methodology development for collective risk assessment of medical irradiation, basing on results of radiation-hygienic passportization in the Russian Federation regions, i.e. using values of collective effective doses for big groups of medical technologies: photoroentgenography, roentgenography, roentgenoscopy, and computer tomography. Use of the effective dose concept for medical irradiation risk definition involves a number of essential restrictions. Age and sex of the employees and of general population (effective dose concept has been developed for these groups of people) may essentially differ from those in patients. Lifelong risk of stochastic effects occurrence in children is 2-3 times higher than the rating values used in effective dose concept, while for elderly people (about 60 years at irradiation time) it’s 4-5 times lower. The article suggests the algorithm of effective doses values correcting factors assessment for consideration of dependence of radiogenic cancer risk factors on age and sex. This enables to assess more correctly collective risk of radiology and nuclear medicine imaging. Since patients tend to be elderly and their risk factor is below the rating used in the effective dose concept, the values of these correcting factors for most radiology and nuclear medicine imaging are below one. Thus, in most cases, the effective dose concept leads to conservative assessment of medical irradiation collective risk.

The paper presents the method of risk assessment for the population of regions of the Russian Federation from exposure to radon based on data from radiation-hygienic passports of territories.

Internal exposure to radon and progeny in dwellings and public buildings prevails in the dose from natural sources of radiation in Russia. The high variability of radon concentration in buildings in different regions of Russia makes it possible to conduct interregional comparisons of radon-induced lung cancer risk.

The data from radiation-hygienic passports include only the effective dose from exposure to radon and progeny and thus reflects only the average radon concentration in a region. There is no description of critical groups of population or detailed characteristics of the exposure. For this reason it seems unpractical to apply risk assessment models with modifying factors that require the development of complex exposure scenarios. In this case it seems reasonable to apply one of the models based on the results of pooled analyses of data from residential case-control studies mentioned in the ICRP Publication 115. Such models take into account the combined effect of smoking and exposure to radon.

The paper describes the procedure for calculating three risk estimates that could be used to characterize a given region or for interregional comparisons. Calculating some of risk estimates requires additional demographic and medical data, which can be obtained from different sources of official statistics.

The methods: Linear differential equations were used to formalize contemporary assumptions of self –sustaining tissue cell kinetics under the impact of adverse factors, on the formation and repairing of cell “pre-cancer” defects, on inheritance and retaining such defects in daughter cells which results in malignant neoplasms, on age-dependent impairment of human body’s function to eliminate such cells.

The results: The model reproduces the well-known regularities of radiogenic cancer morbidity increase depending on instantaneous radiation exposure age and on attained age: the relative reduction at increased radiation age which the model attributes to age decrease of stem cells, relative reduction at increased time after radiation induced by “sorting out” of cells with “pre-cancer” defects, absolute increase with age proportional to natural cause mortality rate.

The relevance of the developed quasi-biological model is displayed via comparison to the ICRP model for radiogenic increase of solid carcinomas’ morbidity after single radiation exposure. The latter model had been developed after Japanese cohort observations. For both genders high goodness-of-fit was achieved between the models at values of Gompertz’ law factor which had been defined for men and women in this cohort via selecting the value of the only free parameter indicating age-dependent exponential retardation of stem cells’ division.

The conclusion: The proposed model suggests that the estimation of radiogenic risk inter-population transfer can be done on the basis of the data on age-dependent mortality intensity increase from all natural causes. The model also creates the premises for inter-species transfer of risk following the well-known parameters of cell populations’ kinetics in animal’s organs and tissues and Gompertz’s law parameters. This model is applicable also for analyses of age-dependent changes of background cancer morbidity.

This work aims at radionuclide diagnostics analyses in the Russian Federation city of St. Petersburg over 2005–2014. The study covers trends and development challenges , availability of radionuclide diagnostics for population needs, exposure doses for patients.

This work aims at radionuclide diagnostics analyses in the Russian Federation city of St. Petersburg over 2005–2014. The study covers trends and development challenges , availability of radionuclide diagnostics for population needs, exposure doses for patients.

Materials and methods. The radionuclide diagnostics temporal and structural changes’ analysis was based on Federal state statistical observation forms No.3-DOZ for St. Petersburg and on the results of radionuclide diagnostics subdivision surveys with radiology physicians’ questionnaires on the amount and composition of conducted examinations, dosages of introduced radioactivity of radiopharmaceticals and patients’ doses.

The results. Since the end of 1990s until 2012 the amount of radionuclide diagnostics procedures had been steadily reducing. 74000 procedures were conducted in 2005 and 35500 in 2012. The number of radionuclide diagnostics procedures per one thousand residents reduced from 16 to 7.2. Both indicators slightly grew in 2013. In 2014 the total number of radiodiagnostic proceduress amounted up to 42000 and 8.2 tests per 1000 residents. Since 2011 the diagnostic equipment was upgraded. Four medical institutions received SPECT (single photon emission computed tomography) or SPECT/CT, two new PET ( positron emission tomographs) – centers were set up, three medical institutions had acquired positron emission tomographs (PET) and are conducting PET – diagnostics receiving radiofarmaceuticals from external PET – center. At the same time one a third of radiodiagnostic units still has been operating obsolete and depreciated equipment dating back to 1980–1990 .

Inspection results indicated that St. Petersburg healthcare centers for in vivo diagnostics were using 24 radiofarmaceuticals, traced 99mTc, 123I, 131I, 67Ga, for PET – diagnostics – radiofarmaceuticals with cyclotron radionuclides 18F, 11C, 13N, 15O. 60–70% are traced 99mTc. Over 10 years the radiodiagnostics structure has changed towards increased number of scintigraphic studies and reduction of “functional” (radiometric) procedures which reflects the changes in the equipment of the radionuclide diagnostics units, the replacement of the old equipment by new SPECT.

         The mean effective dose per one radiodiagnostic test in St. Petersburg is 2.4 mSv. Scintigraphic tests’ mean exposure doses are between 0.9 mSv and 7 mSv. Patients are exposed to the highest doses during whole body diagnostics with administration of 67Ga- citrate and 123I – sodium iodide (about 20 mSv and above). During heart and brain diagnolstics patient’s exposure dose averages 4 mSv. Radiometric (functional) tests’ exposure doses are 0.1 – 0.3 mSv.

Conclusion. Since 2013 the amount of radionuclide diagnostic tests has increased.

The main objective is to modernize the radionuclide diagnostics equipment in the city. After replacement of the old equipment by the state-of-the art one in most probability high- dose diagnostics will increase in number which will result in increased radionuclide diagnostics contribution into population medical exposure dose. Statistical observation form of patients’ medical exposure doses 3 – DOZ requires modernization in the part of radionuclide diagnostics in compliance with advancement in this medical sphere.

In 2010, a study was conducted to determine the air gamma dose rate from 137Cs deposited in soil. The gamma dose rate measurements and soil sampling were performed at 30 reference plots from the south-west districts of the Bryansk region (Russia) that had been heavily contaminated as a result of the Chernobyl accident. The 137Cs inventory in the top 20 cm of soil ranged from 260 kBq m–2 to 2800 kBq m–2. Vertical distributions of 137Cs in soil cores (6 samples per a plot) were determined after their sectioning into ten horizontal layers of 2 cm thickness. The vertical distributions of 137Cs in soil were employed to calculate air kerma rates, K, using two independent methods proposed by Saito and Jacob [Radiat. Prot. Dosimetry, 1995, Vol. 58, P. 29–45] and Golikov et al. [Contaminated Forests– Recent Developments in Risk Identification and Future Perspective. Kluwer Academic Publishers, 1999. – P. 333–341]. A very good coincidence between the methods was observed (Spearman’s rank coefficient of correlation = 0.952; P<0.01); on average, a difference between the kerma rates calculated with two methods did not exceed 3%. The calculated air kerma rates agreed with the measured dose rates in air very well (Spearman’s coefficient of correlation = 0.952; P<0.01). For large grassland plots (n=19), the measured dose rates were on average 6% less than the calculated kerma rates. The tested methods for calculating the air dose rate from 137Cs in soil can be recommended for practical studies in radiology and radioecology.

The goal of research was to determine the level of knowledge among the population on issues like sources of ionising radiation, methods of ionising radiation measurement, measures of self-protection in case of threating or actual radioactive pollution in the district, and to study self-estimation by the population of their knowledge of radiation safety issues.

 Research was carried out using the method of questioning of population groups in three regions close to the places of previous peaceful nuclear explosions (Arkhangelsk, Murmansk and Tyumen regions), and in five Far East regions of the Russian Federation (Kamchatka, Khabarovsk, Primorsky, Magadan and South-Sakhalin regions) after radiation accident in Japan at "Fukushima-1" NPP. This research included processing of 243 questionnaires from the regions close to places of previous peaceful nuclear explosions and 216 questionnaires from the Far East regions.

The analysis of obtained questioning results enabled to make the following conclusions: the level of knowledge among the population about the basic concepts of radiation safety appeared to be generally low among respondents of all eight territories. Considerable number of respondents in seven groups correctly mentioned the x-ray device as a source of ionising radiation (from 71 to 88 % of answers). In Murmansk region – only 52 % of the answers. Respondents of the same seven groups often correctly answered the question on how to detect ionising radiation (only with devices) – from 68 to 98 % in different groups. The smallest number of correct answers to this question (42 %) is also noted among respondents from the Murmansk region.

Level of knowledge on self-protection measures at threating or actual radioactive pollution of the places of residence appeared a little higher among the Far East region population, who had actual concerns regarding the threat of radioactive pollution at the present time. However, in all eight investigated groups many respondents did not know the right answers on self-protection measures, even the simplest ones – like “to close the windows”, “to search for additional information”, etc.

 Obtained data analysis enables to recommend organizations responsible for population protection against excessive radiation impact to use all methods of passive and active population informing on their optimum behavior in case of threating or actual radioactive pollution of the district, and to improve their knowledge of radiation safety basic issues.

In 2016, St. Petersburg Research Institute of Radiation Hygiene after Professor P.V. Ramzaev celebrates 60-th anniversary since its’ foundation. Mindful of the Institute as the research organization 60 years is not too much but it was exactly that time period which spanned radiation hygiene’s origination and development as science. The Institute was established only just 11 years after Hiroshima and Nagasaki bombings, against the backdrop of nuclear weapons tests when the awareness of ionizing radiation’s disastrous consequences for population and environment was not just confined to a narrow circle of specialists. By that time the famous F-1 reactor had already been in operation and new perspectives of nuclear energy peaceful use were lying ahead. There had been an urgent need for scientific studies on personnel and population safety, for development of research hardware, for special personnel in-service training etc. So the Institute’s creation was necessitated by life itself, by objectives unthinkable without a specialized scientific research organization.

Since the very beginning, the Institute specialists mostly aimed at studying technogenic radiation sources. That was the very purpose of the Institute’s creation. Nevertheless almost simultaneously with that the Institute had initiated studies on natural  radioactivity. New devices had been created in order to identify natural and technogenic radionuclides at such levels which are hardly achievable even these days. It will be demonstrated below that some of the 1970s and 1980s hardware  developments retained their uniqueness.

Mindful of the upcoming jubilee we consider it expedient to think back to the most outstanding scientists who had made a profound contribution into the establishment of the Institute as the contemporary scientific school of radiation hygiene and domestic hygienic science.

This publication describes the infancy of the natural sources dosimetry laboratory. Subsequently it is planned to display the further advancement laboratory’s studies of natural radiation as one of population exposure major sources.

One of parameters which should be controlled and annually logged in the territories radiation hygiene passports is the total volume beta activity of the atmospheric air in the form of an average annual value in Bq/m3 units. On different years in the territories radiation hygiene passports there were logged the data on the content of certain radionuclides; however the data on the atmospheric air total volume beta activity were the most informative in all the years. In majority of territories these data are obtained by the Federal Hydrometeorology and Environmental Monitoring Service divisions, in some Russian Federation entities the measurements are carried out by Rospotrebnadzor bodies. However, in the recent years in most Russian Federation entities radiation hygiene passports there are entered design values of the air total volume beta activity, derived using the method of averaging the data on geographic areas.

This article is an attempt to generalize the data on the air total volume beta activity in radiation hygiene passports of the Russian Federation entities, to assess long-term stability of this parameter and opportunity to establish numerical values which may be used as a reference at atmospheric air radiation hygienic monitoring. The article proves that at normal operation of radiation objects on the territory of some Russian Federation entities (excluding zones of large radiation objects supervision in these territories) the atmospheric air average annual total volume beta activity value is stable enough. It is determined that on some years the parameter average annual values in the territories of Saint-Petersburg, Krasnoyarsk region and Khanty-Mansi autonomous region – Yugra differ up to 50% from the average levels derived by long-term observation. The atmospheric air average annual total volume beta activity numerical values assessment is obtained; these values may be accepted as reference levels at atmospheric air radiation hygienic monitoring. Possible reasons are analyzed of atmospheric air total volume beta activity level distinctions on the territory of considered Russian Federation entities.

The study was aimed at personnel and population exposure dose assessment from all main activities and radiation sources in Voronezh region. Assessment of Voronezh Region’s population exposure doses from ionizing radiation sources was conducted using the data of the Federal healthcare institution “Voronezh Region’s Hygiene and Epidemiology Center” on the basis of information derived from forms of Federal state statistical observation over 2010- 2014: No.1-DOZ “Information on personnel exposure doses under normal operation of technogenic ionizing radiation sources” No.3- DOZ ‘Information on patients’ exposure doses during X-ray – radiological tests”, No.4- DOZ “Information on population exposure doses from natural and technogenically impacted background” and the data from Voronezh Region’s radiation-hygienic passport over 2010–2014. It was established that the situation related to Voronezh Region’s ionizing sources impact remains stable over the recent 5 years. Dose interval distribution of groups A and B personnel headcount demonstrated that 58.2% of persons are exposed to doses in the range between 1 and 2 mSv/year and 3.6% to 2-5 mSv/year, respectively. The median yearly effective doses of natural human radiation exposure are in the intervals between 2.350 and 4.480 mSv per year which is typical for this territory. The median effective dose from medical tests per one treatment in different years is between 0.30 and 0.41 mSv. X-ray and computer tomography make the largest contribution into collective population medical radiation dose- 35.6% and 27.8% respectively.

 On the whole population’s major dose contributors are natural ones. Natural factors’ annual contribution into annual effective dose is between 74.96 and 79.68 %.