Hasil untuk "Radioactivity and radioactive substances"

Larissa M. Gonçalves, Olga M. O. Araujo, Alessandra S. Machado et al.

X-ray computed microtomography (microCT) is an advanced technique for evaluating materials that uses the principle of X-ray attenuation to form high-resolution two- and three-dimensional images. This technique allows detailed visualization of the microstructures of biological samples through the digital combination of hundreds of cross-sections. As a non-destructive technique, microCT requires minimal sample preparation and does not cause damage to the analyzed material. This work aims to use microCT to obtain high-resolution images of the ex-vivo uterus, demonstrating the possibility of visualizing microstructures, detailing tissues and contributing to the anatomical and pathological study of these organs. The research also highlights the relevance and usefulness of microCT as a modern and effective technique for the non-destructive analysis of biological samples, emphasizing its potential in several areas of science and medicine. In addition, it seeks to validate microCT as an essential tool for medical research, providing a deeper understanding of the internal structures of organs and their possible pathologies.

V. S. Repin, K. V. Varfolomeeva, A. M. Biblin et al.

The article presents results of a study on the tritium concentrations in seawater samples collected from September 2023 to June 2024 in coastal waters of the Far Eastern regions of the Russian Federation, including Primorsky, Kamchatka, and Khabarovsk Krais; Sakhalin and Magadan Oblasts; and the Chukotka Autonomous Okrug. The aim of the study is to determine the backgrounds values of tritium volume activity. The low-background liquid scintillation spectrometer-radiometer for alpha and beta radiation "Quantulus 1220” was used to determine the baseline tritium content in 185 seawater samples collected by specialists from the territorial bodies of Rospotrebnadzor in six subjects of the Far Eastern Federal District. The results indicate that the specific activity levels for the observation period from September 2023 to June 2024 were below 10.0 Bq/kg in samples collected from the coastal waters of the Far Eastern regions of the Russian Federation. The recorded tritium levels are significantly below the intervention level for drinking water (7600 Bq/L) as per NRB-99/2009, which applies to desalinated seawater.

Regio dos Santos Gomes, Carlos José Da Silva, José Ubiratan Delgado et al.

Short half-life radionuclides are essential for Nuclear Medicine. These radionuclides are usually linked to a more complex molecular or cellular structure with pharmacological characteristics. This set is called “radiopharmaceutical” and have been applied for the diagnosis and therapy of diseases. The use of radiopharmaceuticals involves exposure to ionizing radiation, which, although carefully controlled, poses potential health risks to patients and healthcare professionals. To minimize these risks and maintain the benefits of its use, the radiopharmaceutical dose must be administered to patients with high accuracy and precision, this places  on National Metrology Institutes new requirements for improvement for primary standardization of these short half-life radionuclides, so that the standards used to calibrate the activity meters in hospitals and nuclear medicine clinics have the greatest possible precision. Iodine-123 is currently used for several applications in radiodiagnosis, the main being in pathologies and tumors in the thyroid. In this work is presented the primary standardization of 123I performed by 4παβ(LS)-γ(NaI(Tl)) live timed anticoincidence counting and no significant radionuclidic impurities have been detected by high resolution gamma ray spectrometry. With this work, LMNRI/IRD prepared for the key comparison of the BIPM K4 series using the SIRTI instrument.

Jorge Alexandre Gomes Lins, José Wilson Vieira, Fernando Roberto de Andrade Lima et al.

This study aims to create a source catalog for Lower Limb Lymphoscintigraphy (LLL) examinations in Nuclear Medicine, using real lymphoscintigraphy images from adult male patients. The DIP (Digital Image Processing) software, developed by the Research Group on Computational Dosimetry and Embedded Systems (GPDC&SE), was used to adjust the anteroposterior (AP) and posteroanterior (PA) medical images to the frontal section of the anthropomorphic phantom MASH_sup (Male Adult meSH in supine position). The images were summed line by line, generating a .SGI file, which was processed by the Monte Carlo software to produce the source catalog stored in the file MSUPLC_TC99m.txt. This file contains information for each slice, including the slice number, the area of the source points, and the value of the associated cumulative distribution function (CDF). As a result, a catalog based on real clinical data was successfully generated, which enables the replacement of generic internal sources in the Computational Exposure Models of the GPDC&SE. This makes it possible to simulate LLL examinations more realistically. In the future, this methodology may be extended to female patients, different phantoms, and other scintigraphic procedures. This work represents an advancement in computational dosimetry and personalized nuclear medicine, as it enables simulations that more accurately reflect patient-specific anatomical and physiological characteristics.

Hanyi Zhang, Kaizhong Deng, Zhaoyang Jacopo Hu et al.

Radioguided surgery, such as sentinel lymph node biopsy, relies on the precise localization of radioactive targets by non-imaging gamma/beta detectors. Manual radioactive target detection based on visual display or audible indication of gamma level is highly dependent on the ability of the surgeon to track and interpret the spatial information. This paper presents a learning-based method to realize the autonomous radiotracer detection in robot-assisted surgeries by navigating the probe to the radioactive target. We proposed novel hybrid approach that combines deep reinforcement learning (DRL) with adaptive robotic scanning. The adaptive grid-based scanning could provide initial direction estimation while the DRL-based agent could efficiently navigate to the target utilising historical data. Simulation experiments demonstrate a 95% success rate, and improved efficiency and robustness compared to conventional techniques. Real-world evaluation on the da Vinci Research Kit (dVRK) further confirms the feasibility of the approach, achieving an 80% success rate in radiotracer detection. This method has the potential to enhance consistency, reduce operator dependency, and improve procedural accuracy in radioguided surgeries.

Jaewoong Jang

Radionuclide identification is a radioanalytical method employed in various scientific disciplines that utilize alpha-particle or gamma-ray spectrometric assays, ranging from astrophysics to nuclear medicine. Radionuclide libraries in conventional radionuclide identification systems are crafted in a manual fashion, accompanying labor-intensive and error-prone user tasks and hindering library customization. This research presents a computational algorithm and the architecture of its dedicated software that can automatically generate tailored radionuclide libraries. Progenitor-progeny recurrence relations were modeled to enable recursive computation of radionuclide subsets. This theoretical concept was incorporated into open-source software called RecurLib and validated against four actinide decay series and twelve radioactive substances, including a uranium-glazed legacy Fiestaware, natural uranium and thorium sources, a $^{226}$Ra sample, and the medical radionuclides $^{225}$Ac, $^{177}$Lu, and $^{99\text{m}}$Tc. The developed algorithm yielded radionuclide libraries for all the tested specimens within minutes, demonstrating its efficiency and applicability across diverse scenarios. The proposed approach introduces a framework for computerized radionuclide library generation, thereby trivializing library-driven radionuclide identification and facilitating the spectral recognition of unregistered radionuclides in radiation spectrometry.

Mauricio Gomez, Arnaldo Prata Mourão

Phantoms can be used as quality control objects in computed tomography (CT) imaging and dosimetry in specific regions of interest. By means of phantom tests, alternatives can be created to optimize the acquisition protocols and thus modify the acquisition parameters to deposit lower levels of radiation to the patient, seeking a quality image for the diagnosis. Radiochromic films, GAFCHROMIC XR-AQ2 model, are used to measure the dose-response when exposed to radiation. The profile of the absorbed dose within a phantom is important because it allows an understanding of a larger reality. Calibration curves were obtained from radiochromic films using a cylindrical phantom made of polymethyl methacrylate (PMMA). This phantom has five openings, one central and four peripherals lagged 90°. The phantom was positioned in the isocenter of the gantry of a scanner manufactured by the Toshiba, model Asterion, using 120 and 135 kV voltage of the X-ray tube. The phantom peripheral openings were positioned similarly to positions 3, 6, 9, and 12 of the analog clock. The ionization chamber was used for the record values of the Air Kerma in PMMA, in the central and 12 positions when the central slice of the phantom was irradiated in the axial mode. The other openings were filled with rods also made of PMMA. Radiochromic film strips were placed into PMMA rods and the central and 12 openings were filled. The central area of the phantom was scanned in helical mode. The film strips were digitized and processed their images to have the calibration curve survey.

S. Yu. Bazhin, E. N. Shleenkova, G. N. Kaidanovsky et al.

The analysis of published data on the average annual effective doses to personnel of Russia, Germany, Switzerland, France and Canada in dynamics for 2013-2017 was performed. It was established that in the countries under consideration there are significant differences in the processing of primary measurement information, the calculation on its basis of individual effective doses, as well as ways of averaging the data obtained and their presentation. Factors that may lead to different interpretations of the results are considered: – taking into account background doses due to natural radiation; – use in processing the results of various (in different countries) values of the minimum level of registration; – dose averaging in the absence of activity periods (loss of a dosimeter / vacation), and when registering unexpectedly high doses. These differences exist between the data of foreign countries, but the data presented by the Russian Joint state system of control and accounting of the individual doses of the citizens are especially different. It is shown that the data on average annual effective doses to personnel presented in the Federal Data Base of personnel exposure doses within the framework of the Russian Joint state system of control and accounting of the individual doses is 3-4 times higher than in foreign countries. It is shown that such a difference is caused not by actually high doses, but by the method of processing primary information and averaging data during generalization. It should be noted that such differences occur only for extremely small doses of technogenic exposure to personnel, and do not lead to a significant impact on the overall assessment of the state of radiation safety in the country, but when comparing with other countries, it is necessary to understand the reasons for such differences. The purpose of this work was to identify the causes of these discrepancies and to develop a method for processing primary measurement information and averaging the data when summarizing the results, which allows them to be significantly reduced. Such a method should ensure that the effective doses of personnel closest to the conditionally true values are obtained in the entire range of values, and can be used to summarize the data contained in the Federal Data Base of personnel exposure doses. Since the conversion of the data contained in the Federal Data Base of personnel exposure doses was not the task of the authors of this article, in order to achieve this goal, an attempt was made to process and summarize the measurement results (total 23 204) of the quarterly values of the individual dose equivalent Hp (10) obtained in the Laboratory of Radiation Control of Saint-Petersburg Research Institute of the Radiation Hygiene after Professor P.V. Ramzaev. Such processing has been performed. The subsequent comparison showed that the average annual effective doses to the personnel of medical organizations of St.-Petersburg, in which individual dosimetric control was carried out in the Laboratory of Radiation Control, transformed according to the developed algorithm, are much better consistent with similar data from foreign countries.

T. A. Kormanovskaya, I. K. Romanovich

In 2019 Technical regulations of the Eurasian economical Union “On the safety of the bottled water, including natural mineral water” TR EAES 044/201 entered into force. These regulations established strict requirements to the indicators of the radiation safety for the bottled water, including natural mineral water. Application of these requirements in practice of the sanitary service led to the ban of the use of the bottled medical-table natural mineral water from the Zheleznovodsk site (Stavropolskiy krai), exploited from the well 69-bis by the criteria of the radiation safety. This study proposes possible solutions to the problem of the regulation of the natural mineral water by the radiation factor, complying to the existing requirements on the radiation safety as well as the proposals of the Institute of Radiation Hygiene on the changes in the Technical regulation TR EAES 044/201 and introduction of the requirements on the radiation safety of the natural mineral water in the legislation of the Russian Federation.

V. I. Lyashuk

The synthesis of isotopes is possible under conditions of power electric discharge in the atmosphere. Knowledge of the radioactive 14C yield under flash conditions (as additional channel of 14C production relative to the main - cosmogenic one) is important for radiocarbon analysis. It is proposed the gross model for evaluation of the upper limit of the 14C yield, which creation was simulated for the altitudes up to 15 km. It is presented the results for yield of radioactive isotope 41Ar which synthesis goes along with 14C creation under thunderstorm conditions. It was obtained that the possible thunderstorm mechanisms of 14C creation cannot compete with cosmogenic production.

Chuanya Cao, Nan Li, Xiaoyu Yang et al.

The Jiangmen Underground Neutrino Observatory will build the world's largest liquid scintillator detector to study neutrinos from various sources. The 20 kt liquid scintillator will be stored in a $\sim$600 t acrylic sphere with 35.4 m diameter due to the good light transparency, chemical compatibility and low radioactivity of acrylic. The concentration of U/Th in acrylic is required to be less than 1 ppt (10$^{-12}$ g/g) to achieve a low radioactive background in the fiducial volume of the JUNO detector. The mass production of acrylic has started, and the quality control requires a fast and reliable radioassay on U/Th in acrylic. We have developed a practical method of measuring U/Th in acrylic to sub-ppt level using the Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The U/Th in acrylic can be concentrated by vaporizing acrylic in a class 100 environment, and the residue will be collected and sent to ICP-MS for measuring U/Th. All the other chemical operation is done in a class 100 clean room, and the ICP-MS measurement is done in a class 1000 clean room. The recovery efficiency is studied by adding the natural nonexistent nuclei $^{229}$Th and $^{233}$U as the tracers. The resulting method detection limit (MDL) with 99% confidence can reach 0.02/0.06 pg $^{238}$U/$^{232}$Th /g acrylic with $\sim$75% recovery efficiency. This equipment and method can not only be used for the quality control of JUNO acrylic, but also be further optimized for the radioassay on other materials with extremely low radioactivity, such as ultra-pure water and liquid scintillator.

Daisy Mary Marchezini dos Santos, Clédola Cássia Oliveira de Tello

The Radioactive Waste Management includes the operations since generation of the waste until its storage in repository, ensuring the protection of human beings and the environment from the possible negative impacts. The radioactive waste is segregated, treated, conditioned in suitable packages for posterior storage or disposal in repository. The “RBMN Project” objective is to implement the repository for the disposal of low and intermediate level radioactive wastes generated by nuclear activities in Brazil, proposing a definitive solution for their storage. Engineered and natural barriers as the backfill and coverage layers will compose the disposal system of a near surface repository, concept proposed by the “RBMN Project”. The use of these barriers aims to avoid or restrict the release of radionuclides from the waste to the human beings and environment. The waterproofing barriers are composed of clays. Certainly, for the national repository, will be used those clays existing in the place where it will be constructed. Them some basic tests will have to be carried out to verify the suitability of these clays as barriers. These tests were determined and performed with reference clay, a Brazilian bentonite constituted of 67.2% montmorillonite. The results were compared with national and international literature of materials with similar mineralogical features. The values found with 95% of confidence interval were 9.73±0,35 µm for granulometric size; 13,3±0,6% for the moisture content and 816±9 mmol.kg-1 for the capacity of cationic exchange. A protocol for characterization of clay was elaborated presenting these tests for it future use.

S. Obara, Y. Gando, K. Ishidoshiro

Environmental radioactivity is a dominant background for rare decay search experiments, and it is difficult to completely remove such an impurity from detector vessels. We propose a scintillation balloon as the active vessel of a liquid scintillator in order to identify this undesirable radioactivity. According to our feasibility studies, the scintillation balloon enables the bismuth--polonium sequential decay to be tagged with a 99.7\% efficiency, assuming a KamLAND (Kamioka Liquid scintillator AntiNeutrino Detector)-type liquid scintillator detector. This tagging of sequential decay using alpha-ray from the polonium improves the sensitivity to neutrinoless double-beta decay with rejecting beta-ray background from the bismuth.

A. L. Barabanov, O. A. Titov

Due to a directional asymmetry of neutrino emission caused by parity violation, a sample of radioactive atoms experiences a small recoil force from neutrino radiation accompanying electron capture by polarized nuclei. An expression for this force is obtained for the case of allowed nuclear transitions. Prospects to measure this force by the use of modern micromechanical devices are considered. Numerical estimates for the force are presented for a number of most suitable radioactive isotopes. Potential applications for the weak interaction studies are discussed including the possibility to search for hypothetical Lorentz invariance violation.

D. N. McKinsey

A hypothesis is proposed to explain the long-standing DAMA/LIBRA puzzle. Introduced into the DAMA/LIBRA shielding is a purge gas of nominally high-purity nitrogen, which under this hypothesis contains argon impurities. Argon is introduced into the nitrogen purge gas either through leaks in the purge gas plumbing, or through commercially-supplied bottled nitrogen, diffuses through materials in the detector housings, and then comes in direct contact with the DAMA/LIBRA detectors. These argon impurities can then lead to a modulating 2.8 keV background under two scenarios. Scenario 1): These impurities include the isotope 37Ar, which decays by electron capture, emitting a 2.8 keV x-ray. These decays appear as single-site, monoenergetic events in DAMA/LIBRA, and produce an annual modulation due to the variation of neutron flux in the atmosphere and at the Earth's surface, which in turn leads to a seasonal variation in 37Ar production from the reactions $^{40}\textrm{Ca}(\textrm{n,}α)^{37}\textrm{Ar}$ and $^{36}\textrm{Ar}(\textrm{n,}γ)^{37}\textrm{Ar}$. Scenario 2): Radon is also in the DAMA/LIBRA purge gas, modulating seasonally at a rate below the current DAMA/LIBRA limits. When radon or its short-lived daughters decay, the resulting beta, gamma, and bremsstrahlung radiation cause stable 40Ar to be ionized within the copper housings surrounding the NaI(Tl) detectors, resulting in characteristic 2.8 keV x-rays. Modulating backgrounds might also result from radon-induced neutron or gamma-ray flux from the surrounding cavern, leading to a small modulating background enhanced at low energy by the presence of 40Ar within the copper housings. These two scenarios are straightforward to test through assay of the purge gas as well as Monte Carlo and laboratory study of the DAMA/LIBRA copper housings when excited by ionizing radiation.

D. V. Kononenko

The paper presents the methods of risk assessment from exposure to radon. Proposed methods implement a differentiated approach to the risk estimates calculation procedure which depends on the purpose of risk assessment. This approach is based on the analysis of the results of practical tests of different risk assessment models on arrays Russian medical and demographic data with and without consideration of the synergistic effect of smoking, in simple and complex exposure scenarios. All of these tests were performed in previous 5 years (results are available elsewhere). In this work the evaluation of effectiveness of radon mitigation actions in schools was used as a test task and results obtained using 4 models («EPA-2003», «Wismut-2006», «FCZ» and «Tomasek-2014») were compared. If it is important to evaluate the effect of reduction of radon concentration on the health of children and adolescents in terms of lifetimelung cancer risk, «Tomasek-2014» model will be the best choice. It is as sensitive as «FCZ» model and ERR is close to that from «Wismut-2006» model, which was earlier proposed by other authors for use with some modifications in Russia. If the data on radon concentration are limited (for example data from radiation-hygienic passports of territories) and constant lifelong exposure scenario is considered, it seems reasonable to apply more simple «Darby-2005» model. Thus, the proposed methods could be used by specialists in various fields in a wide range of tasks, from the risk assessment for  the purposes of radiation-hygienic certification and comparative assessment of radiation safety of the population of different regions of Russia on the basis of the generalized statistical data, to the risk assessment in practical works where large amounts of measurement data on the radon concentration and complex exposure scenarios are used.

Warley Ferreira Felix, Marcos Eugenio Silva Abrantes, Marcos Juliano Magalhães et al.

Com o aumento do uso de técnicas de reconstrução 3D, para auxiliar no diagnóstico, os programas dedicados estão sendo largamente utilizados. Para isto eles devem ser calibrados a fim de conhecer os valores dos volumes e número de TC dos tecidos humanos. O objetivo é indicar valores de correção para volumes e número de TC, lidos em um sistema de reconstrução 3D utilizando imagens DICOM de Tomografia Computadorizada. Este trabalho utilizou um fantoma de tórax de PMMA associado a imagem DICOM e o programa de um tomógrafo em função do volume. Para gerar a correção do número de TC foi utilizado o fantoma Catphan e comparado seus valores ao do fabricante associado a reta de linearidade. O volume físico do fantoma de PMMA encontrado foi de 10445,24 cm³ e número de TC de (123,5 ± 33,4) UH. Para os volumes encontrados de acordo com as estruturas de interesse os valores são de 10201,54 cm³, 10242,48 cm³ e 9968,58 cm³ e os valores de correções são de +1,61%, +1,94% e +3,86% respectivamente para tecidos: pulmonar, ósseo e mole. Para os números de TC encontrados neste programa foram de (106,58 ± 55,49) UH, (117,92 ± 90,89) UH e (109,67 ± 25,69) UH e correções de +13,7%, +4,52% e 11,2% respectivamente para tecidos: pulmonar, ósseo e mole. O procedimento realizado pode ser empregado em outros programas de reconstrução 3D e onde houver ferramentas para leituras de número de CT, observando as correções necessárias.

V. P. Utrobin, N. N. Chugai

We explore the well-observed type IIP SN 2013ej with peculiar luminosity evolution. It is found that the hydrodynamic model cannot reproduce in detail the bolometric luminosity at both the plateau and the radioactive tail. Yet the ejecta mass of 23-26 Msun and the kinetic energy of (1.2-1.4)x10^51 erg are determined rather confidently. We suggest that the controversy revealed in hydrodynamic simulations stems from the strong asphericity of the Ni-56 ejecta. An analysis of the asymmetric nebular H-alpha line and of the peculiar radioactive tail made it possible to recover parameters of the asymmetric bipolar Ni-56 ejecta with the heavier jet residing in the rear hemisphere. The inferred Ni-56 mass is 0.039 Msun, twice as large compared to a straightforward estimate from the bolometric luminosity at the early radioactive tail. The bulk of ejected Ni-56 has velocities in the range of 4000-6500 km/s. The linear polarization predicted by the model with the asymmetric ionization produced by bipolar Ni-56 ejecta is consistent with the observational value.

Amanda Anastacio Soares, Flávio Augusto Penna Soares, Gabrielly Gomes Kahl

Desenvolveu-se uma equação direta para estimar a dose absorvida pelo paciente em exames radiográficos, utilizando parâmetros elétricos, geométricos e de filtragem combinados com dados da anatomia irradiada. Para determinar a dose absorvida em cada exame, a Dose de Entrada na Pele (DEP) é ajustada à espessura da anatomia específica do paciente. A DEP é calculada a partir da estimativa da grandeza KERMA no ar. Equações de Lambert-Beer derivadas de dados de coeficientes de absorção de energia em massa obtidos do NIST/EUA, foram desenvolvidas para cada tecido: osso, músculo, gordura e pele. A espessura da pele foi fixada em 2 mm e a dos ossos foi estimada no local do raio central, na incidência ântero-posterior. Por serem similares em densidade e coeficientes de atenuação, músculo e gordura são tratados como um tecido único. Para avaliação das equações completas, escolheu-se 3 anatomias distintas: tórax, mão e coxa. Embora complexas em seu formato, as equações simplificam a determinação direta de dose absorvida a partir das características do equipamento e paciente. Os dados de entrada são inseridos em um único momento e a dose absorvida total (mGy) é calculada instantaneamente. O erro médio, ao comparar-se com dados disponíveis, é menor do que 5% em qualquer combinação de dados de aparelho e exames. Além do cálculo da dose para determinado exame e paciente, o operador pode escolher as variáveis que irão depositar menos radiação no paciente por meio da análise prévia de cada combinação de variáveis, empregando o principio ALARA na rotina do setor de radiodiagnóstico.

I. A. Zvonova, L. A. Chipiga, M. I. Balonov et al.

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.