PURPOSE:In order to estimate the effect of radiation exposure on the workers of a uranium enterprise, teeth samples were collected for EPR dosimetry of tooth enamel from workers of uranium mines living in Shantobe settlement (Akmola region, Northern Kazakhstan) and from residents of this settlement who had never worked in the mine as a control. METHODS:The accumulated radiation doses in enamel were estimated based on the magnitude of the radiation-induced EPR signal in the samples. Excess (additional) doses were obtained after subtracting the contribution of natural radiation at typical levels during enamel age, and they were interpreted as caused by radiation in the work environment and by radioactive contamination of the territory. RESULTS:For the personnel of the uranium mining enterprise (17 teeth samples), the average excess dose was 90 ± 20 mGy (standard uncertainty of the average is indicated here and below). For the rest of the population who did not work at the mine (10 teeth samples), the average excess dose is estimated at 20 ± 12 mGy. CONCLUSIONS:A higher mean dose and greater variation were observed for miners in comparison to non-mining people in the same settlement. These differences were likely due to the occupational exposure.

Radioactive compounds, including silicon dioxide (31SiO2), may enter the environment and affect biological systems, yet their impact on the gut microbiota remains poorly studied. This study aimed to evaluate the effects of radioactive 31SiO2, compared to non-radioactive SiO2 and gamma irradiation, on the composition and functionality of the gut microbiota in laboratory Wistar rats (n = 28). Gut microbiota analysis of the large intestine, small intestine, and Peyer’s patches was conducted at 90 min and 72 h post-exposure using 16S rRNA sequencing. Alpha-diversity results showed increased species richness in Peyer’s patches at 90 min after exposure to radioactive 31SiO2, with elevated Bacilli and Gammaproteobacteria, a trend persisting at 72 h. In the small intestine, radioactive 31SiO2 increased Bacilli and Clostridia at 3 days, while Gammaproteobacteria considerably decreased; by 72 h, Bacilli and Clostridia maintained growth, with Gammaproteobacteria recovering. These findings demonstrate that radioactive 31SiO2 dynamically alters gut microbiota composition and diversity, highlighting its unique influence on microbial communities.

Studies on health effects of radiation exposure to residents around the Semipalatinsk nuclear test site (SNTS), Kazakhstan, are necessary for epidemiological assessment of radiation-related health risks after low-dose irradiation. Radiation dose estimates are the principal point for radiation epidemiological studies. These estimates should be based on the most reliable initial data, used for dose estimations. The comparative critical analysis of various available archival and published initial data, namely values of historical exposure dose rates and values of soil contamination by 137Cs in considered settlements, including information about dates, times and locations of measurements, was performed with the aim to select most reliable and realistic initial data necessary for estimation of settlement-average accumulated external doses for some settlements located in the vicinity of radioactive clouds' trajectories related to the most significant tests at the SNTS. Results of estimation of accumulated external radiation dose to air, based on these selected initial data, are presented for 18 settlements. Calculated accumulated external doses were compared with retrospective instrumental dose estimates for settlements, where data on TL/OSL luminescence retrospective dosimetry with quartz-containing samples or electron spin resonance (ESR) dosimetry with tooth enamel were available. Estimation of settlement-average external radiation dose to air is the first important step necessary for the next step-individualized radiation dose estimations among different age, professional and ethnic-specific groups of population lived in the study settlements considering behavior, shielding, location and relocation factors in each population group. This is a subject of future work.

To assess the impact of natural and technogenic radioactivity in uranium mining enterprises on the population, an investigation by the tooth enamel EPR (Electron Paramagnetic Resonance) dosimetry method was conducted for a group of the population living in the Stepnogorsk city (North Kazakhstan) placed near a uranium mining plant. Accumulated radiation EPR doses in enamel were assessed for 96 teeth samples.From the measured values of EPR doses and the age of tooth enamel since its formation, the individual annual EPR dose rates (DR) were determined with average value of 1.75±0.46 mGy/year corresponding to the hourly DR of 0.20±0.05 µGy/hour (here and below after ± sign the error of the mean is shown). Data on the individual DR were analyzed for samples collected for population of different parts of Stepnogorsk (microdistricts). These data were compared with ambient dose equivalent rate (ADER) of gamma radiation measured by the conventional instrumental dosimetry. No significant differences in DR and ADER between microdistricts were found. The average ADER through the microdistricts of Stepnogorsk was 0.23±0.01 µGy/hour (corresponding to 2.0±0.1 mGy/year), which is consistent with the average DR measured by EPR.For some tooth donors significantly higher individual EPR doses and DR, exceeding up to several times the bulk level for the investigated group of population were obtained. These high values may be result of local increased radiation level caused by the wastes of uranium mining enterprises.

Aim of the study – develop a unified approach for calculating spatial distributions of absorbed energy of ionizing radiation within and outside of biostructures with various shapes and sizes at internal irradiation by corpuscular and photon radiation in order to simplify procedures and to reduce the volume of calculations for dosimetrical support to use of radiopharmaceuticals in nuclear medicine. The data bases, containing information on spatial distributions in biological tissue of absorbed energy, emitted by point isotropic sources of corpuscular and photon radiation, were used. Numerical data characterizing absorbed fractions of energy inside and outside the volumes of biological structures modeled by spheres and layers of different sizes at internal irradiation by alpha particles, electrons and photons in the energy ranges of 0.01-10 MeV, 0.0005-10 MeV and 0.015-4.0 MeV, respectively, were obtained. This almost completely covers the energy spectra of all radionuclides used in nuclear medicine. It has been established that numerical sequences of calculated values of absorbed fractions of energy, expressed as dependences of fractions of energy on the ratios of biological structures’ sizes or distances around them to the so-called “radii of 99% absorption of energy around point sources”, becomes a unified form applicable to biostructures of various sizes and shapes at internal irradiation by corpuscular and photon radiation with different energies. The proposed approach is useful tool for calculating absorbed doses inside and outside the volumes of organs and tumor formations, at the level of their microstructures, as well as at the cellular and subcellular levels.

To understand the biological effects of residual radioactivity after the atomic bomb explosion in Hiroshima and Nagasaki, we previously investigated the effects of 56Mn, a major residual radioisotope. Our rat study demonstrated that inhalation exposure to 56MnO2 microparticles affected gene expression in the lungs, testes, and liver, despite the low radiation doses. Because 56Mn is a β- and γ-emitter, the differential effects between β- and γ-rays should be clarified. In this study, 31Si, a β-emitter with a radioactive half-life similar to that of 56Mn, was used to determine its effects. Male Wistar rats were exposed to sprayed neutron-activated 31SiO2 microparticles, stable SiO2 microparticles, or X-rays. The animals were examined on days 3 and 14 after irradiation. The expression of radiation-inducible marker genes, including Ccng1, Cdkn1a, and Phlda3, was measured in the spleen, lungs, and liver. Furthermore, the expressions of pathophysiological marker genes, including Aqp1, Aqp5, and Smad7 in the lungs and Cth, Ccl2, and Nfkb1 in the liver, were determined. Impacts of 31SiO2 exposure were observed mainly in the liver, where the expression of Cth markedly increased on post-exposure days 3 and 14. Our data suggest that internal exposure to β-emitted microparticles has significant biological effects and its possible roles as residual radiation after atomic bombing.

Radiobiological studies are ongoing to understand the consequences of internal exposure to neutron-activated radioactive microparticles, which were sprayed over experimental rats and mice. Special attention in these experiments is given to internal irradiation with radioactive microparticles with short-lived neutron-activated radionuclides 31Si (T-1/2 = 2.62 h) and 56Mn (T-1/2 = 2.58 h), which are among the main dose-forming factors from residual radioactivity activated in soils by neutrons in the first hours after atmospheric nuclear explosions. The presented work is devoted to microdosimetry peculiarities of (SiO2)-Si-31 and (MnO2)-Mn-56 microparticles. The radiation from Si-31 consists of intensive short-range beta particles and gamma rays with very low intensity. It differs from the radiation of Mn-56, which includes intensive beta particles, low energy Auger electrons and very intensive gamma rays. Differences in the energies and intensities of short-range beta particles and penetrating gamma rays emitted by (SiO2)-Si-31 and (MnO2)-Mn-56 microparticles can lead to differences in the spatial microdistribution of absorbed dose around the corresponding radioactive microparticles embedded in biological tissue. It was found in the presented work that the absorbed doses of beta radiation emitted by (MnO2)-Mn-56 and (SiO2)-Si-31 microparticles has significant but different spatial gradients with distances in biological tissue that correspond to the typical thickness of epithelial cells of lungs' alveoli and bronchioles. The results obtained are necessary for a better understanding of radiobiological effects of internal exposure by radioactive microparticles with Mn-56 and Si-31 observed in framework of performed and ongoing radiobiological studies with experimental animals-rats and mice.

Neutron-activated Si-31 is an almost pure beta emitter and is one of the short-lived radionuclides, including beta-gamma emitter Mn-56, which were created in a form of residual radioactivity in the early period after the atomic bombing of Hiroshima and Nagasaki. The features of the biological effects of internal irradiation by these radionuclides are a subject of scientific discussions and research. The publication presents data on internal radiation doses in experimental Wistar rats that were exposed to sprayed neutron-activated microparticles of (SiO2)-Si-31. Doses of internal radiation could be conditionally divided into three groups according to their values. It has been found that elevated values of internal radiation doses in rats' organs/tissues as a result of exposure to sprayed (SiO2)-Si-31 microparticles with initial activity of 3.2 x 10(7) Bq varied from 10 to 120 mGy (eyes, lungs, skin, stomach, jejunum, large intestine). The moderate dose values were in the range from 1.9 to 3.7 mGy (trachea, esophagus, ileum). The smallest doses were received by the kidney, testis, blood, cerebellum, heart, liver, cerebrum, bladder, spleen and thymus (from 0.11 to 0.94 mGy). The obtained data are important for interpreting the results of ongoing and planned biological experiments with (SiO2)-Si-31 microparticles-in comparison with the previously published data on features of biological effects caused by beta-gamma emitting (MnO2)-Mn-56 neutron-activated microparticles.

For correct assessment of health risks after low-dose irradiation, calculation of radiation exposure estimates is crucial. To verify the calculated absorbed doses, instrumental methods of retrospective dosimetry are used. We compared calculated and instrumental-based estimates of external absorbed doses in the residents of Dolon, Mostik and Cheremushki villages, Kazakhstan, affected by the first nuclear weapon test performed at the Semipalatinsk Nuclear Test Site (SNTS) on August 29, 1949. The ‘instrumental’ doses were retrospectively estimated using the Luminescence Retrospective Dosimetry (LRD) and Electron Spin Resonance (ESR) methods. Correlation between the calculated individual cumulative external absorbed whole-body doses based on typical input data and ESR-based individual doses in the same people was strong (r = 0.782). It was even stronger between the calculated doses based on individual questionnaires’ input data and the ESR-based doses (r = 0.940). Application of the LRD method is useful for validation of the calculated settlement-average cumulated external absorbed dose to air. Reconstruction of external exposure can be supplemented with the data from later measurements of soil contamination with long-lived radionuclides, such as, 137Cs. Our results show the reliability of the calculational method used for the retrospective assessment of individual external doses.

About 10% of all malignant liver neoplasms are inoperable both in Russia and worldwide. The most effective treatment of these patients is chemo- and radioembolization. For the treatment of inoperable primary and secondary liver cancer using intra-arterial radioembolization, a Russian radiopharmaceutical (RF) has been developed based on albumin microspheres with a diameter of 20-40 microns, labeled with the radioisotope rhenium-188 (RP “Gepatoren-MRRC”). Preclinical studies and phase 1 clinical studies were conducted. The aim of this work was the investigation of the safety of RP “Hepatoren-MRRC” during radioembolization in patients with inoperable primary and secondary liver cancer and selection of safe and maximum tolerated dose of the radiopharmaceutical. Intra-arterial radioembolization with Hepatoren-MRRC, 3-6 GBq, was given to 20 patients with the following diagnoses: primary liver cancer (C22.0, C22.1), metastatic liver cancer (C19.0, C22.1, C18.7, C18.0, C20.0). All patients underwent whole-body scintigraphy and SPECT at 2, 24, 48, and 72 h after procedure. Radiometry of patients' urine, which was taken within 48 h after radioembolization, was also performed. The patients were followed up for 3 months. Urinary excretion of RP was an average 23% [12%-40%] during 48 h after treatment. No accumulation of free 188Re in the thyroid gland was observed. A small (5.5%-13.2%) pulmonary shunt was observed in all patients. The diagnostic SPECT/CT image with RP «99mTc-MAA» in all patients coincided with the post-therapy SPECT/CT image with RP “Hepatoren-MRRC”. Internal radiation doses delivered to tumor ranged from 9.2 to 68.5 Gy. The values of individual radiation doses delivered to critical organs were many times less than the generally accepted dose limits for radiotherapy. Grade 1 of haematological toxicity was observed in 15 (75%) patients, grade 2 – in 3 (15%) patients, grade 3 – in 2 (10%) patients. Grade 2 of hepatological toxicity was observed in all patients. Good tolerability of RP was observed in 10 (50%) patients, satisfactory tolerability – in 7 (35%) patients and unsatisfactory tolerability – in 3 (15%) patients. No significant complications were identified during the follow-up period. One patient died 2 months after radioembolization by reason of progression of the main disease. According to the results of the Phase 1 of clinical trial we can conclude about safety and tolerability of RP “Hepatoren-MRRC” of 3-6 GBq for radioembolization in patients with inoperable liver cancer.

Aim of the study – use of the phenomenon of thermo stimulated luminescence in natural microcrystals of sea salt (NaCl) in the range of therapeutic doses in order to develop a method for off line intracavitary «in vivo» dosimetry of patients at high dose-rate brachytherapy of prostate cancer with a 192Ir source. Samples of aliquots with natural microcrystals (a fraction with a size of about 100 m) of sea salt were used in the study. Measurements were carried out using a Harshaw 3500 device, which is a thermoluminescent reader. Irradiation of samples to construct the calibration dependences was carried out by a standard 90Sr/90Y source providing the dose rate of 2.99 mGy/s. It was established, that: (1) there is a linear dose dependence of luminescence intensity from studied microcrystals in the range of therapeutic absorbed doses from 1 to 20 Gy with an error in measuring the luminescence intensity of the studied microcrystal samples of less than 5%; (2) it was revealed that fading (decrease in microdosimeter readings over time) does not exceed 5% 5 days after irradiation; (3) clinical testing of «in vivo» dosimetry method using sea salt microcrystals for high dose-rate brachytherapy of prostate cancer shows that the results of measurements of absorbed doses in the organ at risk (rectum) using studied natural NaCl crystals are consistent, within the limits of error, with the results of measurements by synthetic LiF:Mg,Ti crystals (with intracavitary placement in the organ at risk and simultaneous irradiation both assemblies of these microcrystals). It was concluded that the use of the studied sea salt microcrystals is promising for «in vivo» dosimetry in application to 192Ir high dose-rate brachytherapy of prostate cancer.

To assess the impact of natural and technogenic radioactivity near uranium mining enterprises on the population, an investigation by the tooth enamel EPR (Electron Paramagnetic Resonance) dosimetry method was conducted for a group of the population living in Stepnogorsk city placed near an uranium mining plant (North Kazakhstan). Accumulated radiation doses in enamel samples were assessed for 97 teeth samles. From the measured values of the accumulated dose and the age of tooth enamel since its formation, the individual annual doses with average value of 1.52±0.28 mGy/year were determined (corresponding to the hourly EPR dose rate of 0.17+/-0.04 µGy/hour). Data on the individual EPR dose rate were compared with gamma dose rate measured by the conventional instrumental dosimetry for population of different parts of the city (microdistricts). No significant differences in the instrumental dose rates between microdistricts were found, although some tendency towards increased dose rate in the north-eastern part of the city was observed. This is just in the direction where the uranium mining dumps are placed, located at the distance of about 20 km from the city. The average instrumental dose rate measured inside the inhabitance was 0.20+/-0.02 µGy/hour, which is consistent with the average EPR dose rate.

The cluster of calculational and instrumental methods for estimation of personalized internal radiation doses to foci and organs at risk among patients undergoing to therapy by radiopharmaceuticals has been developed. The developed set of methods was used for dosimetrical support of clinical trials of therapeutic radiopharmaceuticals: a) Lu-177-DOTA-PSMA (or "Lutaprost") targeted for radioligand therapy of metastatic castrate-resistant prostate cancer; b) Re-188 albumin microspheres 5-10 μm (or "Artroren") targeted for radiosynovectomy in the local treatment of chronic inflammatory diseases of the joints and c) 188Re albumin microspheres 20-40 μm (or "Gepatoren") targeted for intra-arterial radionuclide embolization in the treatment of inoperable liver cancer. The results of estimations absolute activities of radiopharmaceuticals and their dynamics during SPECT/CT scanning of radiopharmaceuticals in the body of patients were verified by measurements using physical phantoms of humans with different body weights and various standard activities of radionuclides distributed inside the phantoms. The developed cluster of programs (for calculating the absorbed fraction of energy in biostructures), relevant databases and instrumental methods were used as the basis for estimations personalized internal radiation doses in foci and organs at risk among patients included in clinical trials of the studied radiopharmaceuticals. Individual internal radiation doses in foci among 39 patients, included in the first phase of clinical trials of the three studied radiopharmaceuticals, were estimated. The analysis of the distribution of estimated doses shows that absorbed doses in foci are very differing not only in different patients, but also in different foci in the same patient. Irradiation doses in foci increase with an increasing in the administered activities of radiopharmaceuticals and, depending on the volume of foci, are within the following ranges: 1) in a case of “Lutaprost” – from 1.4 to 32 Gy (planned administered activity – 5 GBq), from 5.1 to 59 Gy (planned activity – 7.5 GBq), from 13 to 94 Gy (planned activity – 10 GBq); 2) in a case of "Arthroren" – from 17.5 to 74 Gy (planned administered activities – from 0.37 to 0.925 GBq); 3) in a case of “Gepatoren” – from 10.7 to 43 Gy (planned administered activities – from 1 to 3 GBq). Individual absorbed doses in organs at risk were estimated as well. Dose values in organs at risk also vary greatly between different patients and between different critical organs. These doses ranged from 0.01 to 7.4 Gy (39 patients), which is many times less than “commonly applied dose constraints” in radiotherapy.

The effects of residual radiation from atomic bombs have been considered to be minimal because of its low levels of external radioactivity. However, studies involving atomic bomb survivors exposed to only residual radiation in Hiroshima and Nagasaki have indicated possible adverse health effects. Thus, we investigated the biological effects of radioactive dust of manganese dioxide 56 (56MnO2), a major radioisotope formed in soil by neutron beams from a bomb. Previously, we investigated C57BL mice exposed to 56MnO2 and found pulmonary gene expression changes despite low radiation doses. In this study, we examined the effects in a radiation-sensitive strain of mice, BALB/c, and compared them with those in C57BL mice. The animals were exposed to 56MnO2 particles at two radioactivity levels and examined 3 and 65 days after exposure. The mRNA expression of pulmonary pathophysiology markers, including Aqp1, Aqp5, and Smad7, and radiation-sensitive genes, including Bax, Phlda3, and Faim3, was determined in the lungs. The radiation doses absorbed in the lungs ranged from 110 to 380 mGy; no significant difference was observed between the two strains. No exposure-related pathological changes were observed in the lungs of any group. However, the mRNA expression of Aqp1 was significantly elevated in C57BL mice but not in BALB/c mice 65 days after exposure, whereas no changes were observed in external γ-rays (2 Gy) in either strain. In contrast, Faim3, a radiation-dependently downregulated gene, was reduced by 56MnO2 exposure in BALB/c mice but not in C57BL mice. These data demonstrate that inhalation exposure to 56MnO2 affected the expression of pulmonary genes at doses <380 mGy, which is comparable to 2 Gy of external γ-irradiation, whereas the responses differed between the two mouse strains.

Objective: Previously, low-dose radiation therapy was used for pneumonia treatment. We aimed to investigate the safety and effectiveness of carbon nanoparticles labeled with Technetium isotope (99mTc) in a form of ultradispersed aerosol in combination with standard COVID-19 therapy. The study was a randomized phase 1 and phase 2 clinical trial of low-dose radionuclide inhalation therapy for patients with COVID-19 related pneumonia. Methods: We enrolled 47 patients with confirmed COVID-19 infection and early laboratory signs of cytokine storm and randomized them into the Treatment and Control groups. We analyzed blood parameters reflecting the COVID-19 severity and inflammatory response. Results: Low-dose 99mTc-labeled inhalation showed a minimal accumulation of radionuclide in lungs in healthy volunteers. We observed no significant differences between the groups before treatment in WBC-count, D-dimer, CRP, Ferritin or LDH levels. We found that Ferritin and LDH levels significantly raised after the 7th day follow-up only in the Control group (p < 0.0001 and p = 0.0005, respectively), while mean values of the same indicators did not change in patients in the Treatment group after the radionuclide treatment. D-dimer values also lowered in the radionuclide treated group, however, this effect was not statistically significant. Furthermore, we observed a significant decrease in CD19+ cell counts in patients of the radionuclide-treated group. Conclusion: Inhalation low-dose radionuclide therapy of 99mTc aerosol affects the major prognostic indicators of COVID-19- related pneumonia restraining inflammatory response. Overall, we identified no evidence of major adverse events in the group receiving radionuclide.

The investigation of the radiation effects of the atomic bombing in Hiroshima and Nagasaki has revealed concerns about the impact of the residual radioactive dust produced in the soil. Manganese-56 is one of the major radioisotopes produced by neutrons from the bomb; hence, we previously examined the biological effects of manganese dioxide-56 (56MnO2) in Wistar rats, in which significant changes were found in the lung. In the present study, ten-week-old male C57BL mice were exposed to three doses of radioactive 56MnO2, stable MnO2 particles, or external γ-rays (2 Gy) to further examine the effects of 56MnO2 in a different species. The estimated absorbed radiation doses from 56MnO2 were 26, 96, and 250 mGy in the lung. The animals were examined at 3, 14, and 70 days post exposure. Histologically, no exposure-related changes were found in the lungs of any group. However, pulmonary mRNA expression of aquaporin 1, which is a useful marker for lung pathophysiology, was significantly elevated at 14 and 70 days, although no such changes were found in the mice exposed to external γ-rays (2 Gy). These data indicated that the inhalation exposure to 56MnO2 particles, with <250 mGy of organ doses, produced significant biological responses in the lung.

INTRODUCTION: The results of studies of clinical potential of a new domestic radiopharmaceutical 177 Lu-DOTA-PSMA in patients with metastatic castration-resistant prostate cancer are presented in this article. OBJECTIVE: The pharmacokinetics, safety and tolerability of radiopharmaceutical were studied. Tolerability of increasing activities — 5.0, 7.5 and 10.0 GBq was investigated. MATERIALS AND METHODS: The study included 12 patients with metastatic castration-resistant prostate cancer, who progressed after previous treatment. The first 4 patients was treated by 5 GBq of 177 Lu DOTA-PSMA, the next 4 patients of the second group was treated by 7.5 GBq, and the 4 patients of the third group was treated by 10 GBq. Radiopharmacokinetics was studied by whole-body scintigraphy, SPECT/CT, blood and urine radiometry. The radiation-absorbed dose (RAD) of metastases and organs at risk was studied by clinical dosimetry. Safety assessment also was studied by hematological status. All patients was taken a complete blood count, a biochemical blood test before course of therapy treatable and during the case study. RESULTS: Study data showed high accumulation of 177 Lu-DOTA-PSMA the in pathological focus, the distribution in the body conformed to the previous data of PET/CT study. Blood radiometry showed that 177 Lu-DOTA-PSMA rapidly excreted from the bloodstream (during the first hours after injection). Urine radiometry showed that, more than half of the injected dose was excreted during 2 days (from 34.4% to 88.8%). DISCUSSION: During the study was solicited increasing of pain syndrome, dry mouth. Most patients had moderate myelosuppression. Changes in hematological parameters had a transistor character, the adverse event resolved without consequences in 5 week. 4 th grade of NCI CTCAE hematological toxicity criteria wasn’t identified. Serious adverse events weren’t identified too. CONCLUSIONS: Radiopharmaceutical demonstrated high affinity for tumor tissue and safety in the clinical use. Data, which demonstrating a high potential anti-tumor efficacy of radiopharmaceutical, were obtained. Dosimetric studies showed radiation safety of work with radiopharmaceutical for the personnel.

Internal radiation exposure from neutron-induced radioisotopes environmentally activated following atomic bombing or nuclear accidents should be considered for a complete picture of pathologic effects on survivors. Acute and localized high dose radiation exposure from hot particles taken into the body must induce cell death and severe damage to tissues, whether they are proliferating or not. However, very little the cellular and molecular mechanisms underlying this internal radiation pathology has been investigated. Male Wistar rats were internally exposed to 56 MnO 2 powder by inhalation. Small intestine samples were investigated by histological staining at acute phase (6 h, 3 days and 14 days) and late phase (2, 6 and 8 months) after the exposure. Histological location and chemical properties of the hot particles embedded in small intestinal tissues were analyzed by synchrotron radiation—X-ray fluorescence—X-ray absorption near-edge structure (SR–XRF–XANES). Hot particles located in the intestinal cavity were identified as accumulations of Mn and iron. Pathological changes showed evidence of crypt shortening, massive cell death at the position of stem cell zone, including apoptosis and pyroptosis from 6 h through 8 months in the internal exposed rats.

This work aims to evaluate the application of optical and X-ray spectroscopy methods to determine the effect of alpha-emitting radionuclides on the properties of solid-state nuclear track detectors (SSNTD) based on nitrocellulose during their detection. The proposed estimation methods are alternative methods to standard technologies, making it possible to determine the concentration of radon and its decay products without the chemical etching of film detectors and subsequent direct counting of the formed latent tracks from interacting particles. During the research, it was found that the use of optical spectroscopy and X-ray diffraction methods makes it possible to qualitatively determine the irradiation effect on changes in the properties of film detectors when α-particles with different energies pass through them. At the same time, a comparison of the data of optical spectroscopy, X-ray diffraction and the visualization of latent tracks after chemical etching made it possible to establish that a part of the registered α-particles in living quarters has an energy of less than 2.5 MeV, which is not enough to pass through the polymer film of the detector, as a result of which well-like tracks are formed. An increase in the intensity of the interference bands in the region above 700 nm and a decrease in the intensity of diffraction reflection characterized the changes in optical transmission. The penetration of the α-particles through the detecting film decreases the film’s transmission capacity, forming an anisotropic change in diffraction reflections associated with a change in the film’s structure and defective fractions distorting the molecular structure.

Abstract The aim of overview is to present the pooled data of published internal dose estimates and the results of corresponding analysis of internal irradiation features of experimental mice and rats after exposure to sprayed neutron activated radioactive 56MnO2. These dose estimates were conducted in a framework of multicenter international study to investigate biological effects as a result of exposure to sprayed radioactive 56MnO2 microparticles. Radionuclide 56Mn (T1/2 = 2.58 h) is one of the main gamma-beta emitters during the first hours after neutron activation of soil following nuclear explosion. It was concluded that there are three groups of organs of mice and rats, the radiation doses of which differ by approximately an order of magnitude: the group with the highest radiation doses (large and small intestine, stomach, skin and lungs), the group with lowered radiation doses (eyes, esophagus, trachea), the group with the lowest radiation doses (liver, heart, kidneys). The radiation doses to organs are proportional to the activity of the sprayed radioactive powder. The distribution of internal radiation doses among organs of experimental mice of different strains but of the same age was practically the same in case of exposure to the same activity of sprayed 56MnO2 powder. Doses of internal irradiation of experimental mice substantially exceed the doses of internal irradiation of experimental rats exposed to the same activities of the sprayed 56MnO2 powder. The data presented in the overview can be helpful for further investigation and for interpretation of the biological effects of this type of irradiation.