Quantitative risk assessment of radiocesium associated with Japanese foods imported into the United Kingdom.

Damage to a nuclear power station resulted in radioactive contamination of certain areas of Japan in 2011. Legislation was put in place in Europe to establish controls on the import of certain types of food and feed, including a limit of 100 radioactive decays (becquerel, Bq) per second of radiocesium per kg. This legislation was retained in the United Kingdom after leaving the EU and then reviewed in 2021. A quantitative risk assessment was developed to estimate the radiological risk to public health from consuming Japanese food imported into the United Kingdom should the maximum level on radiocesium be removed. Although Japanese monitoring data indicated occurrences when products exceeded the 100 Bq per kg limit, these were found to be rare; a total of 1485 occurrences (0.0013%) of all measured foodstuff samples (>1 million) within the scope of this assessment had radiocesium activity concentrations that exceeded 100 Bq per kg. Using the recorded occurrence and level of radiocesium measured, and the current pattern and volume of food imported from Japan, there was an estimated excess risk of fatal cancer of around one in a million per year, categorized as negligible compared to the baseline 2018-2020 UK cancer fatality rate of around 1 in 4. On the basis of the described assessment and the estimated small additional risk, Great Britain lifted import controls related to radioactivity present in food from Japan. A number of recommendations to address data gaps and approaches in this assessment are made, particularly how we can improve modeling UK dietary habits for specialist foods.

Treatment accuracy of standard linear accelerator-based prostate SBRT: the delivered dose assessment of patients treated within two major clinical trials using an in-house position monitoring system.

Background and purpose: The purpose of this study was to assess the dosimetric improvements achieved in prostate stereotactic body radiotherapy (SBRT) treatment within the PROMETHEUS and NINJA trials using an in-house real-time position monitoring system, SeedTracker. Methods and materials: This study considered a total of 127 prostate SBRT patients treated in the PROMETHEUS (ACTRN12615000223538) and NINJA (ACTRN12618001806257) clinical trials. The SeedTracker position monitoring system was utilized for real-time position monitoring with a 3-mm position tolerance. The doses delivered to the clinical target volume (CTV), rectum, and bladder were assessed by incorporating the actual target position during treatment. The dose that would have been delivered without monitoring was also assessed by incorporating the observed position deviations. Results: Treatment with position corrections resulted in a mean (range) CTV D99 difference of -0.3 (-1.0 to 0.0) Gy between the planned and delivered dose. Without corrections, this difference would have been -0.6 (-3.7 to 0.0) Gy. Not correcting for position deviations resulted in a statistically significant difference between the planned and delivered CTV D99 (p < 0.05). The mean (range) dose difference between the planned and delivered D2cc of the rectum and bladder for treatment with position corrections was -0.1 (-3.7 to 4.7) Gy and -0.1 (-1.7 to 0.5) Gy, respectively. Without corrections, these differences would have been -0.6 (-6.1 to 4.7) Gy and -0.2 (-2.5 to 0.9) Gy. Conclusions: SeedTracker improved clinical dose volume compliance in prostate SBRT. Without monitoring and corrections, delivered dose would significantly differ from the planned dose.

Individualized dose calculation for internal exposure on radionuclide intake: GPU acceleration approach.

Objective. The rapid and accurate assessment of internal exposure dose is a crucial safeguard for personnel health and safety. This study aims to investigate a precise and efficient GPU Monte Carlo simulation approach for internal exposure dose calculation. It directly calculates doses from common radioactive nuclides intake, like60Co for occupational exposure, allowing personalized assessments.Approach. This study developed a GPU-accelerated Monte Carlo program for internal exposure on radionuclide intake, successfully realizing photoelectronic coupled transport, nuclide simulation, and optimized acceleration. The generation of internal irradiation sources and sampling methods were achieved, along with the establishment of a personalized phantom construction process. Three irradiation scenarios were simulated to assess computational accuracy and efficiency, and to investigate the influence of posture variations on internal dose estimations.Main results. Using the International Commission on Radiological Protection (ICRP) voxel-type phantom, the internal dose of radionuclides in individual organs was calculated, exhibiting relative deviation of less than 3% in comparison to organ dose results interpolated by Specific Absorbed Fractions in ICRP Publication 133. Employing the Chinese reference phantom for calculating internal irradiation dose from the intake of various radionuclides, the use of GPU Monte Carlo program significantly shortened the simulation time compared to using CPU programs, by a factor of 150-500. Internal dose estimation utilizing a seated Chinese phantom revealed up to a 75% maximum difference in organ dose compared to the same phantom in a standing posture.Significance. This study presents a rapid GPU-based simulation method for internal irradiation doses, capable of directly simulating dose outcomes from nuclide intake and accommodating individualized phantoms for more realistic and expeditious calculations tailored to specific internal irradiation scenarios. It provides an effective and feasible tool for precisely calculating internal irradiation doses in real-world scenarios.

A comprehensive review of dose limits, triage systems and measurement tools for consequence management of nuclear and radiological emergencies.

During a radiological or nuclear emergency, occupational workers, members of the public, and emergency responders may be exposed to radionuclides, whether external or internal, through inhalation, ingestion, or wounds. In the case of internalized radiation exposure, prompt assessment of contamination is necessary to inform subsequent medical interventions. This review assembles the constituent considerations for managing nuclear and radiological incidents, focused on a parallel analysis of the evolution of radiation dose limits - notably in the emergency preparedness and response realm - alongside a discussion of triage systems and in vivo radionuclide detection tools. The review maps the development of international and national standards and regulations concerning radiation dose limits, illuminating how past incidents and accumulated knowledge have informed present emergency preparedness and response practices, specifically for internalized radiation. Additionally, the objectives and levels of radiation triage systems are explored in-depth, along with a global survey of practices and protocols. Finally, this review also focuses on in vivo detection systems and their capacities for radionuclide identification, prioritizing internalized gamma-emitting isotopes due to their broader relevance. Collectively, this study comprehensively addresses the intricacies of triage management following radiation emergencies, emphasizing the imperative for enhanced standardization and continued research in this critical domain.

Exposure to radon gas in groundwater in southwest Angola (Lubango-Huíla): Implications of geology and climate change.

In southern African countries most of the population uses groundwater collected in dug wells for domestic consumption instead of water from public distribution systems. To investigate the impact of natural and human factors on urban groundwater quality, 276 samples were collected in the Lubango region (Angola) in water distribution systems and dug wells ranging from a few meters to almost one hundred meters in depth. Radon concentrations (RC) were determined by liquid scintillation counting according to ISO 13164-4:2015. Geology is the main source of the variability of RC, with median values higher than 100 Bq/L in granitoid units and lower values in mafic and sedimentary units (ranging from 5 to 38 Bq/L). On average, RC was higher in dug wells compared to public water distribution systems. The annual effective dose due to ingestion of radon in water is, on average, ten times lower in the later compared to dug wells. Therefore, from a public exposure perspective, water distribution systems are preferred as means for water distribution. A severe multi-year meteorological drought over the past decade affecting 76-94 % of the population in southern Angola has been linked with climate change. Consequently, a regional lowering of the water table was observed, as well as a reduction in the productivity of shallower wells, leading to a search for water at greater depths. This work demonstrates an increase in median RC from 66 Bq/L in wells shallower than 30 m to values over 100 Bq/L with increasing depth of water extraction and for the same geological unit. The highest RC observed were also observed at the deepest wells. The dose ingested is proportional to RC, being also higher at deeper water extraction depths. The increase in public radiation exposure from radon ingestion due to water extraction at greater depths is attributed to the underlying issue of climate change. Monitoring water quality in terms of radionuclide concentration is advised to ensure the exposure to ionizing radiation remains at acceptable levels in the future.

Assessment of the impact of Tianwan Nuclear Power Plant on the adjacent marine ecosystem.

Based on the monitoring data of 137Cs and 90Sr in Tian Bay in 2005-2023, the impacts of the operation of Tianwan Nuclear Power Plant on the marine ecosystem were assessed. The 137Cs and 90Sr activity concentrations in the seawater and sediment varied within the background ranges. The radiation dose rates derived from 137Cs and 90Sr for the marine organisms ranged from 2.4 × 10-5 to 2.2 × 10-4 nGy/h, it was far below the most conservative screening dose rate (10 µGy/h). The committed effective dose for humans was 0.070-0.094 µSv, 1/1500th of the world's mean annual effective dose (0.12 mSv) from ingesting food containing uranium and thorium series nuclides. Radiation risk assessment showed no radiation risk for the long-term discharge of nuclear wastes in the future. Overall, the long-term normal operation of TNPPs has almost no radiation impact on the adjacent marine ecosystem.

Half-century trends of radioactivity in fish from Danish areas of the North Sea, Kattegat, and Baltic Sea.

This work reports comprehensive time-series datasets over the past 50 years for natural (210Po) and anthropogenic (134Cs and 137Cs) radionuclides in three fish species (cod, herring and plaice) from Danish marine areas covering the North Sea, Kattegat, and Baltic Sea. Impact from the global fallout of atmospheric nuclear weapons testing, radioactive discharges from the European nuclear reprocessing plants and release from Chernobyl accident are clearly detected in the fish samples. While 210Po concentrations in each fish species demonstrated comparable levels across the three regions without notable temporal trends, significantly higher median 210Po concentration was observed in the lower trophic level fish, namely herring and plaice, compared to cod. In contrast, 137Cs concentrations in all three species steadily decrease over time after the Chernobyl-attributed peaks in late 1980s in the entire study area, whereas 137Cs always demonstrated higher concentrations in cod than herring and plaice. Our calculated concentration factors (CFs) for 137Cs in this work indicate that the mean CFs for 137Cs over the past 50 years are significantly different across the three species, following the order of cod < herring < plaice. Based on the time-series data, ecological half-lives (Teco) of 137Cs in fish from Danish marine areas were estimated to evaluate the long-term impact of anthropogenic radioactive contamination in different regions. Our results indicate no significant difference in Teco across different fish species, whereas the weighted mean Teco for fish in the Baltic Sea (29.3 ± 3.9 y) is significantly longer than those of the North Sea (9.8 ± 0.9 y) and Kattegat (11.7 ± 1.2 y), reflecting the strong 'memory effect' of the Baltic Sea due to its slow water renewal. However, the dose assessment demonstrates that the contribution of the natural radionuclide 210Po to ingestion dose from fish consumption is 1-2 order of magnitude higher compared to that of 137Cs.

Assessment of natural radioactivity in Moroccan bottled drinking waters using gamma spectrometry.

Radioactive elements and their impact on the environment and the food chain, including humans, are a matter of major concern, for which appropriate investigations should be performed. The priority is to examine the concentration of radioactive substances in mineral and bottled spring water. This task aims to analyze the quality of 12 conditioned mineral waters by determining their main radionuclides concentrations, such as 238U, 232Th, and 40K. The identification and the quantification of these radionuclides are carried out by their progeny (except the 40K) by using a NaI(Tl) detector coupled with a multichannel analyzer (MCA) and connected to a computer. The activity measured in all samples varied from 0.95 to 3.38 mBq.L-1 with an average of 1.94 mBq.L-1; from 1.55 to 3.56 mBq.L-1 with an average of 2.46 mBq.L-1; and from 200.68 to 269.19 mBq.L-1 with an average of 236.6 mBq.L-1, for 238U, 232Th, and 40K, respectively. To compare the combined radiological effects of radionuclides present in water, a particular factor Ra(eq) is used. This study showed that the maximum value of Ra(eq) is 27.54 mBq.L-1, which is far below the activity limit of 370 mBq.year-1 set by the Organization of Economics and Development (OECD). Concerning the effective annual dose, the following maximums were measured: 1.61 µSv.year-1, 1.133 µSv.year-1, and 0.925 µSv.year-1 for infants, children, and adults, respectively. These values are even smaller than the dose recommended by the WHO which is 100 µSv.year-1. Regarding the excess lifetime cancer risk index, a maximum of 5.63 × 10-6 is found. This index value is still less than that proposed by James, namely 2.5 × 10-3. Thus, the quality of the studied samples respects the radiological international safety and health limits.

Experiences from the ARGOS user group nuclear emergency exercise.

The Accident Reporting and Guiding Operational System (ARGOS) is a decision support system used to assist in the Emergency Preparedness and Response (EPR) to nuclear and radiological incidents. The ARGOS user group has been formed that is made up of government agencies across many countries that have a role in EPR to nuclear and radiological incidents. In 2020, a desktop exercise was organised for the members of the ARGOS user group. The exercise involved two hypothetical accidents at different times on the same date, namely a radiological release from a floating nuclear power plant (NPP) off the Norwegian coast and from the Loviisa NPP in Finland. The objectives of the exercise were to train and increase knowledge of the ARGOS system, to perform a comparison of model outputs, and to compare the recommendations of protective actions. In the case of the floating NPP the source term was provided, while in the Loviisa NPP scenario the participants were required to provide their own source term based on a description of the accident. The results on radiological consequences based on dispersion modelling, protective actions, source terms and dispersion modelling settings were collected from participants. A comparison was made between each of these reported aspects. In general, it was found that there was general agreement between the results for the floating nuclear power plant scenario in the sense of plume direction and extent, while in the case of the Loviisa NPP scenario, there was much greater variation, with the difference in source term estimates between the participants being an influencing factor. The participants acknowledged that taking part in an exercise of this nature increased their knowledge and understanding about using decision support tools such as ARGOS in planning and responding to nuclear and radiological emergencies.

Quantitative assessment of adaptive radiotherapy for prostate cancer using deep learning: Bladder dose as a decision criterion.

BACKGROUND: Adaptive radiotherapy (ART) can incorporate anatomical variations in a reoptimized treatment plan for fractionated radiotherapy. An automatic solution to objectively determine whether ART should be performed immediately after the daily image acquisition is highly desirable. PURPOSE: We investigate a quantitative criterion for whether ART should be performed in prostate cancer radiotherapy by synthesizing pseudo-CT (sCT) images and evaluating dosimetric impact on treatment planning using deep learning approaches. METHOD AND MATERIALS: Planning CT (pCT) and daily cone-beam CT (CBCT) data sets of 74 patients are used to train (60 patients) and evaluate (14 patients) a cycle adversarial generative network (CycleGAN) that performs the task of synthesizing high-quality sCT from daily CBCT. Automatic delineation (AD) of the bladder is performed on the sCT using the U-net. The combination of sCT and AD allows us to perform dose calculations based on the up-to-date bladder anatomy to determine whether the original treatment plan (ori-plan) is still applicable. For positive cases that the patients' anatomical changes and the associated dose calculations warrant re-planning, we made rapid plan revisions (re-plan) based on the ori-plan. RESULTS: The mean absolute error within the region-of-interests (i.e., body, bladder, fat, muscle) between the sCT and pCT are 41.2, 25.1, 26.5, and 29.0HU, respectively. Taking the calculated results of pCT doses as the standard, for PTV, the gamma passing rates of sCT doses at 1 mm/1%, 2 mm/2% are 87.92%, 98.78%, respectively. The Dice coefficients of the AD-contours are 0.93 on pCT and 0.91 on sCT. According to the result of dose calculation, we found when the bladder volume underwent a substantial change (79.7%), the bladder dose is still within the safe limit, suggesting it is insufficient to solely use the bladder volume change as a criterion to determine whether adaptive treatment needs to be done. After AD-contours of the bladder using sCT, there are two cases whose bladder dose D mean > 4000 cGy ${{\mathrm{D}}}_{{\mathrm{mean}}} > 4000{\mathrm{\ cGy}}$ . For the two cases, we perform re-planning to reduce the bladder dose to D mean = 3841 cGy ${{\mathrm{D}}}_{{\mathrm{mean}}} = 3841{\mathrm{\ cGy}}$ , D mean = 3580 cGy ${{\mathrm{D}}}_{{\mathrm{mean}}} = 3580{\mathrm{\ cGy\ }}$ under the condition that the PTV meets the prescribed dose. CONCLUSION: We provide a dose accurate adaptive workflow for prostate cancer patients by using deep learning approaches, and implement ART that adapts to bladder dose. Of note, the specific replanning criterion for whether ART needs to be performed can adapt to different centers' choices based on their experience and daily observations.

Simulating the impact of particulate matter exposure on health-related behaviour: A comparative study of stochastic modelling and personal monitoring data.

Epidemiological and exposure studies concerning particulate matter (PM) often rely on data from sparse governmental stations. While low-cost personal monitors have some drawbacks, recent developments have shown that they can provide fairly accurate and fit-for-purpose data. Comparing a stochastic, i.e., agent-based model (ABM), with environmental, biometric and activity data, collected with personal monitors, could provide insight into how the two approaches assess PM exposure and dose. An ABM was constructed, simulating a PM exposure/dose assessment of 100 agents. Their actions were governed by inherent probabilities of performing an activity, based on population data. Each activity was associated with an intensity level, and a PM pollution level. The ABM results were compared with real-world results. Both approaches had comparable results, showing similar trends and a mean dose. Discrepancies were seen in the activities with the highest mean dose values. A stochastic model, based on population data, does not capture well some specifics of a local population. Combined, personal sensors could provide input for calibration, and an ABM approach can help offset a low number of participants. Implementing a function of agents influencing others transport choice, increased the importance of cycling/walking in the overall dose estimate. Activists, agents with an increased transport influence, did not play an important role at low PM levels. As concentrations rose, higher shares of activists (and their influence) caused the dose to increase. Simulating a person's PM exposure/dose in different scenarios and activities in a virtual environment provides researchers and policymakers with a valuable tool.

Po-210 activity concentrations in wild and farmed fish from the Aegean Sea and Sea of Marmara and dose assessment to consumers.

Polonium (210Po) is the major contributor (with approximately 90%) to the radiation dose from radionuclides contained in the human diet, and it is mostly associated with seafood. This study presents 210Po activity concentrations in the tissues of 16 fish species from the Aegean Sea and Sea of Marmara. Among all species investigated, the highest 210Po activity concentration was 4450 ± 33 Bq kg-1 dry weight (dw) in the digestive tract of anchovy (Engraulis encrasicolus), and the lowest 210Po activity concentration was 1.3 ± 0.6 Bq kg-1 (dw) in the muscle tissue of the thornback ray (Raja clavata). Significant differences in 210Po concentrations were consistently found among the tissues of fish (P < 0.05). In general, the prominent accumulation of 210Po was observed in the digestive tract and liver while the muscle tissue generally displayed the lower concentrations. Polonium concentrations in the internal organs, such as muscle and liver, were related to the feeding ecology of fish and thus are a consequence of 210Po transfer in the food chain rather than 210Po uptake from water. The average 210Po concentration in fish filet was 54.1 Bq kg-1 dw and to attain the recommended limit for the annual committed effective dose (1 mSv year-1) would require the consumption of 1024 kg of mixed fish filet in 1 year, which is unlikely to happen. The highest 210Po activity concentration in the edible part of fish (filet) was determined in the anchovy (E. encrasicolus) but to reach the 1 mSv year-1 limit would require still the consumption of 7.1 kg year-1 of anchovy filet. Similar size specimens of wild and farmed fish, Dicentrarchus labrax and Sparus aurata, were analyzed to assess the differences in 210Po concentrations. Polonium concentrations in the wild fish were several-fold higher than in farmed specimens, these ones fed with fish feed with 210Po content lower than natural food in the sea. Therefore, the current trend of increasing the consumption of seafood from aquaculture seems to be reducing the radiation exposure to 210Po in the human diet that is considered beneficial to public health.

Using energy expenditure to estimate the minute ventilation and inhaled load of air pollutants: a pilot survey in young Chinese adults.

Existing equations to estimate ventilation (VE) may not represent the Chinese population. The objective is to develop regression equations to predict the basal metabolic rate (BMR) for ventilation estimation. 80 participants underwent the incremental tests on a bicycle ergometer, wearing a fitted facial mask with an airflow sensor connected to the cardiopulmonary gas analyzer, where the energy expenditure, metabolic factors and VE were monitored simultaneously. Linear regression models were established between BMR and body weight, which were used to estimate energy expenditure and VE. Extrapolation of the regression model was evaluated by the five-fold cross-validation. And we also assessed the inhaled load of air pollutants in subgroups at the same exposure levels. Regression models for males and females were BMR (kJ/d) = 107.58 × weight (kg)-172.61 and BMR (kJ/d) = 105.61 × weight (kg)-26.94, respectively. The model showed good fitness between the measured and predicted VE. Differences between the measured and predicted VE of this model are smaller than that of other models. There were significant differences in inhaled load participants in the same exposure concentrations. The regression model showed that weight and BMR are highly correlated and can be used to estimate individual VE.

Assessment of intrafraction motion and its dosimetric impact on prostate radiotherapy using an in-house developed position monitoring system.

Purpose: To implement an in-house developed position monitoring software, SeedTracker, for conventional fractionation prostate radiotherapy, and study the effect on dosimetric impact and intrafraction motion. Methods: Thirty definitive prostate radiotherapy patients with implanted fiducial markers were included in the study. All patients were treated with VMAT technique and plans were generated using the Pinnacle planning system using the 6MV beam model for Elekta linear accelerator. The target dose of 60 Gy in 20 fractions was prescribed for 29 of 30 patients, and one patient was treated with the target dose of 78 Gy in 39 fractions. The SeedTracker position monitoring system, which uses the x-ray images acquired during treatment delivery in the Elekta linear accelerator and associated XVI system, was used for online prostate position monitoring. The position tolerance for online verification was progressively reduced from 5 mm, 4 mm, and to 3 mm in 10 patient cohorts to effectively manage the treatment interruptions resulting from intrafraction motion in routine clinical practice. The delivered dose to target volumes and organs at risk in each of the treatment fractions was assessed by incorporating the observed target positions into the original treatment plan. Results: In 27 of 30 patients, at least one gating event was observed, with a total of 177 occurrences of position deviation detected in 146 of 619 treatment fractions. In 5 mm, 4 mm, and 3 mm position tolerance cohorts, the position deviations were observed in 13%, 24%, and 33% of treatment fractions, respectively. Overall, the mean (range) deviation of -0.4 (-7.2 to 5.3) mm, -0.9 (-6.1 to 15.6) mm, and -1.7 (-7.0 to 6.1) mm was observed in Left-Right, Anterior-Posterior, and Superior-Inferior directions, respectively. The prostate CTV D99 would have been reduced by a maximum value of 1.3 Gy compared to the planned dose if position deviations were uncorrected, but with corrections, it was 0.3 Gy. Similarly, PTV D98 would have been reduced by a maximum value of 7.6 Gy uncorrected, with this difference reduced to 2.2 Gy with correction. The V60 to the rectum increased by a maximum of 1.0% uncorrected, which was reduced to 0.5%. Conclusion: Online target position monitoring for conventional fractionation prostate radiotherapy was successfully implemented on a standard Linear accelerator using an in-house developed position monitoring software, with an improvement in resultant dose to prostate target volume.

Impact of long-term operation of nuclear power plants on the marine ecosystem of Daya Bay.

Based on the monitoring data of Daya Bay in 2011-2017, the impact of long-term operation of nuclear power plants (NPPs) on the marine ecosystem was accessed. 137Cs and 90Sr in seawater and sediment of Daya Bay decreased with time. The environmental half-lives of 137Cs and 90Sr in seawater, 137Cs in sediment were 7.1 a, 11.7 a and 13.9 a, respectively. The total dose rates of the marine organisms ranged from 230.5 to 853.9 nGy/h, lower than the ERICA screening benchmark (10 µGy/h). 210Po, 226Ra and 232Th were the main dose contributors. 137Cs and 90Sr contributed to ~0.01 %-~0.06 % of the total radiation. 137Cs contributed to <0.6 ‰ of the committed effective dose for humans. There were almost no radiation effects on the marine ecosystem of Daya Bay from NPPs before 2017. In the future, there will be no radiation risk for the long-term discharge of low-level radioactive waste to Daya Bay.

Levels, sources, variations, and human health risk assessment of 90Sr and 137Cs in water and food around Sanmen Nuclear Power Plant (China) from 2011 to 2020.

Objectives: Radioactivity monitoring around nuclear facilities is crucial to provide important baseline data for effective detection of radioactive leakage to the environment. We aim to establish a baseline study for monitoring radioactive levels of 90Sr and 137Cs around Sammen Nuclear Power Plant (SNPP) and to assess their associated health impact on surrounding residents. Methods: In this study, we collected water and food samples around the SNPP from 2011 to 2020 and determined for 90Sr and 137Cs activity concentrations. We statistically analyzed the temporal trends of 90Sr and 137Cs and evaluated their radiation exposure to the local residents. Results: During this period, the activity concentrations of 90Sr and 137Cs varied within 1.2-9.9 mBq/L and 0.10-7.6 mBq/L in water, and 0.037-1.3 Bq/kg and 0.011-0.45 Bq/kg in food, respectively, with no significant seasonal variation trend. Conclusions: All reported activity concentrations of 90Sr and 137Cs were significantly lower than the recommended value of WHO and Chinese national standards. There is no indication of notable radioactive release into the study area due to the operation of SNPP during 2018-2020. The annual effective doses (AEDs) from the ingestion of 90Sr and 137Cs in water and food were well below the international permissible limits, indicating the radiation exposure around SNPP during 2011-2020 was kept at a safe level.

Dosimetric Impact of Intrafraction Prostate Motion and Interfraction Anatomical Changes in Dose-Escalated Linac-Based SBRT.

The dosimetric impact of intrafraction prostate motion and interfraction anatomical changes and the effect of beam gating and motion correction were investigated in dose-escalated linac-based SBRT. Fifty-six gated fractions were delivered using a novel electromagnetic tracking device with a 2 mm threshold. Real-time prostate motion data were incorporated into the patient's original plan with an isocenter shift method. Delivered dose distributions were obtained by recalculating these motion-encoded plans on deformed CTs reflecting the patient's CBCT daily anatomy. Non-gated treatments were simulated using the prostate motion data assuming that no treatment interruptions have occurred. The mean relative dose differences between delivered and planned treatments were -3.0% [-18.5-2.8] for CTV D99% and -2.6% [-17.8-1.0] for PTV D95%. The median cumulative CTV coverage with 93% of the prescribed dose was satisfactory. Urethra sparing was slightly degraded, with the maximum dose increased by only 1.0% on average, and a mean reduction in the rectum and bladder doses was seen in almost all dose metrics. Intrafraction prostate motion marginally contributed in gated treatments, while in non-gated treatments, further deteriorations in the minimum target coverage and bladder dose metrics would have occurred on average. The implemented motion management strategy and the strict patient preparation regimen, along with other treatment optimization strategies, ensured no significant degradations of dose metrics in delivered treatments.

Biodose Tools: an R shiny application for biological dosimetry.

INTRODUCTION: In the event of a radiological accident or incident, the aim of biological dosimetry is to convert the yield of a specific biomarker of exposure to ionizing radiation into an absorbed dose. Since the 1980s, various tools have been used to deal with the statistical procedures needed for biological dosimetry, and in general those who made several calculations for different biomarkers were based on closed source software. Here we present a new open source program, Biodose Tools, that has been developed under the umbrella of RENEB (Running the European Network of Biological and retrospective Physical dosimetry). MATERIALS AND METHODS: The application has been developed using the R programming language and the shiny package as a framework to create a user-friendly online solution. Since no unique method exists for the different mathematical processes, several meetings and periodic correspondence were held in order to reach a consensus on the solutions to be implemented. RESULTS: The current version 3.6.1 supports dose-effect fitting for dicentric and translocation assay. For dose estimation Biodose Tools implements those methods indicated in international guidelines and a specific method to assess heterogeneous exposures. The app can include information on the irradiation conditions to generate the calibration curve. Also, in the dose estimate, information about the accident can be included as well as the explanation of the results obtained. Because the app allows generating a report in various formats, it allows traceability of each biological dosimetry study carried out. The app has been used globally in different exercises and training, which has made it possible to find errors and improve the app itself. There are some features that still need consensus, such as curve fitting and dose estimation using micronucleus analysis. It is also planned to include a package dedicated to interlaboratory comparisons and the incorporation of Bayesian methods for dose estimation. CONCLUSION: Biodose Tools provides an open-source solution for biological dosimetry laboratories. The consensus reached helps to harmonize the way in which uncertainties are calculated. In addition, because each laboratory can download and customize the app's source code, it offers a platform to integrate new features.

Clinical 3D/4D cumulative proton dose assessment methods for thoracic tumours with large motion.

PURPOSE: Despite the anticipated clinical benefits of intensity-modulated proton therapy (IMPT), plan robustness may be compromised due to its sensitivity to patient treatment uncertainties, especially for tumours with large motion. In this study, we investigated treatment course-wise plan robustness for intra-thoracic tumours with large motion comparing a 4D pre-clinical evaluation method (4DREM) to our clinical 3D/4D dose reconstruction and accumulation methods. MATERIALS AND METHODS: Twenty patients with large target motion (>10 mm) were treated with five times layered rescanned IMPT. The 3D-robust optimised plans were generated on the averaged planning 4DCT. Using multiple 4DCTs, treatment plan robustness was assessed on a weekly and treatment course-wise basis through the 3D robustness evaluation method (3DREM, based on averaged 4DCTs), the 4D robustness evaluation method (4DREM, including the time structure of treatment delivery and 4DCT phases) and 4D dose reconstruction and accumulation (4DREAL, based on fraction-wise information). RESULTS: Baseline target motion for all patients ranged from 11-17 mm. For the offline adapted course-wise dose assessment, adequate target dose coverage was found for all patients. The target volume receiving 95% of the prescription dose was consistent between methods with 16/20 patients showing differences < 1%. 4DREAL showed the highest target coverage (99.8 ± 0.6%, p < 0.001), while no differences were observed between 3DREM and 4DREM (99.3 ± 1.3% and 99.4 ± 1.1%, respectively). CONCLUSION: Our results show that intra-thoracic tumours can be adequately treated with IMPT in free breathing for target motion amplitudes up to 17 mm employing any of the accumulation methods. Anatomical changes, setup and range errors demonstrated a more severe impact on target coverage than motion in these patients treated with fractionated proton radiotherapy.

Internal radiation exposure from TENORM for workers conducting cleaning activities on equipment used at geothermal energy plant.

Geothermal energy is predicted to be one of the most important renewable energy sources in the near future. In geothermal energy plants, the secondary products such as the scale containing naturally occurring radioactive material (NORM) and adhering to the surface of equipment produce radiation fields. The workers who maintain and clean such equipment are at a risk to be exposed by the technically enhanced NORM (TENORM). To estimate the risks of radiation exposure to the workers, we assessed internal doses resulting from the cleaning activities on 150 heat exchanging boards used at a geothermal energy plant, focusing on 222Rn, 226Ra, 210Pb, 228Ra and 228Th. The experiment was performed with the subjects of workers and office workers as control, supplying prepared foods and drinks. Using the analytical results of 210Pb, 226Ra, 228Ra, and 228Th in the excretions of subjects, committed effect doses were determined. The annual internal dose for the workers with protective clothing due to the cleaning activities on removing scale, assuming the cleaning activities requires 170 h (standard monthly working time) a year, was obtained as 26 µSv/y and the total dose including 222Rn inhalation dose was calculated as 323 µSv/y. The additional dose for the cleaning workers was less than the dose limit of 20000 µSv/y for radiation workers, even less than for general population (1000 µSv/y) recommended by International Commission on Radiological Protection (ICRP). However, the elevated inhalation dose for workers conducting cleaning activities may present a health hazard to workers if they deal with excessive materials containing TENORM, work for excessive time or are under inappropriate safety measures.