Institute for Radiation Protection and Nuclear Safety (IRSN)
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Energy landscape of hydrogen in the vicinity of monovacancy in beryllium
No full textInternational audienceThe present work is devoted to fill the lack of data related to the hydrogen behavior in the vicinity of monovacancy in the hexagonal compact structure of beryllium. These data are of importance to feed coupled reaction–diffusion models dedicated to the simulation of hydrogen behavior in beryllium in order to analyze its thermal release as function of concentration and temperature. This work aims to evaluate the trapping and detrapping energies for several pathways surrounding a vacancy as well as the impact of multiple trapping of hydrogen on these data. In addition, the data to compute the detrapping rates for a single hydrogen are given. The determination of the energy landscape in the vicinity of the monovacancy has shown that the trapping energy varies from 0.39 eV (equal to the activation energy for diffusion in non-defective bulk) down to 0.12 eV while the activation energy for detrapping mechanism rises to 1.08 eV up to 1.48 eV. The lowest detrapping energy, 0.86 eV, is obtained from hydrogen filled vacancy whereas the multi-trapping does not significantly affect the trapping energy
Neurotoxicological outcome of a chemical and radiological co-exposure in rat: low dose gamma irradiation and inhalation of tungsten particles
No full textInternational audienceBackground and PurposeToxicology studies gradually tend to consider the concept of exposome in their experimental design. Each individual is indeed exposed to a unique and wide range of stressors simultaneously, and these stressors might interact. Combining them therefore provides a more realistic representation of an individual’s exposome and the toxicity they experience. Nuclear industry workers integrate specific stressors in their occupational exposome, including external gamma irradiation. It is of particular interest due to uncertainties regarding its dose-response curve in the low dose range, some studies even reporting beneficial neuroprotective effects. Nuclear industry workers are also subject to particulate aerosol inhalation, a major cause of contamination. Our chemical stressor, Tungsten (W), is an emerging contaminant in the environment, used in various industrial or military settings due to its remarkable physical properties. More specifically, nuclear fusion reactors integrate a W shielding which is eroded by the plasma stream during normal operation. The W particles produced pose a risk of exposure of nuclear workers during maintenance, dismantling operations, or loss of vacuum accidents. Although W was initially considered an inert metal, recent national authorities report raise questions about its effective toxicity.Our aim is to explore the differential neurotoxicological effects of a radiological and chemical co-exposure combining W particles inhalation and low dose gamma irradiation and study the mechanisms involved.Methods12-week-old male Sprague-Dawley rats were exposed to a polydisperse aerosol of metal W particles in a nose-only setting (80 mg.m-3, 30 minutes) and/or to a full body low dose gamma irradiation (50 mGy, 50 mGy.min-1). 24 hours (24h) and 28 days (28d) post-exposure, biological samples were collected: whole brains, brain structures, olfactory epithelium, lung, kidney, and plasma. Processes of interest included neuronal integrity, cell survival, oxidative stress, and inflammation in the frontal cortex (FC) and olfactory bulb (OB).ResultsWhile no changes could be observed in OB or FC in apoptosis or proliferation with the markers used, histological studies did unveil statistically significant differences more often between co-exposed and control groups for several parameters, than groups exposed to stressors alone. We observed an increase at 24h and 28d of total cellular density in FC. Microglial density increased at 24h and decreased at 28d in the FC, while activation phenotypes remained unchanged. In OB, both microglial density and activation increased after 28d in the co-exposed group. Analyzing a specific suffering phenotype in FC, we observed a decrease of the density of donut-like neurons at 24h, and an increase after 28d.Gene expression analysis via RT-qPCR revealed a strong heterogeneity of response between FC and OB and the main significant differences were observed for the co-exposed group compared to control. A significant increase of the expression of antioxidant genes in the FC at 28d was observed in parallel with a decrease of these genes in OB. In terms of inflammation, we measured an increased expression of MCP1 in FC at 24h and a decreased expression of TNFɑ in OB at 28d. Conclusions Our goal was to determine whether differential effects could be observed on target processes involved in cerebral toxicity. Co-exposure appears to cause significant effects when compared to control and single stressor groups, hence our discussion and conclusion will focus on the co-exposed groups.Although we see modulations of cell density for microglia and donut-like neurons, our findings do not suggest an increase in cell death or proliferation. The temporal concordance between the microglial depletion in FC and the increase in density in OB at 28d suggests a potential migration of these cells from the FC to the OB in the time window considered. Similarly, the increase in microglial density in FC at 24h is probably caused by a microglial migration from deeper layers of the FC or neighboring microstructures. The changes observed in terms of cytokines gene analysis support the migratory hypothesis as MCP1 expression increases in FC at 24h. The decrease in TNFɑ gene expression in OB at 28d could reflect microglial activation towards anti-inflammatory phenotypes.The antioxidant response appearing in FC at 28d could be the consequence of a disruption in the cerebral microenvironment caused by the microglial depletion. This unbalance in microenvironment could also be increasing the density of donut-like neurons at 28d in FC.Overall, our results suggest heterogeneous responses among structures and an increased effect when combining our stressors. Ongoing experiments are investigating antioxidative mechanisms (transcription factor translocation) and hypoxia contribution. ICP-MS studies will determine the impact of irradiation on the biodistribution of W in our target organs. Additionally, the increase in total cell density observed in FC at both time points cannot be explained entirely by microglial density modulations. Other cell types will be considered in this process (progenitor cells, peripheral cell intrusion). As the modulations are still visible or reversed at 28d, studies should be undertaken beyond this time point to question their persistence
Low to moderate dose 137 Cs (γ) radiation promotes M2 type macrophage skewing and reduces atherosclerotic plaque CD68+ cell content in ApoE (-/-) mice
No full textInternational audienceAbstract The effects of low doses of ionizing radiation on atherosclerosis remain uncertain, particularly as regards the generation of pro- or anti-inflammatory responses, and the time scale at which such effects can occur following irradiation. To explore these phenomena, we exposed atheroprone ApoE (−/−) mice to a single dose of 0, 0.05, 0.5 or 1 Gy of 137 Cs (γ) administered at a 10.35 mGy min −1 dose rate and evaluated short-term (1–10 days) and long-term consequences (100 days). Bone marrow-derived macrophages were derived from mice 1 day after exposure. Irradiation was associated with a significant skewing of M0 and M2 polarized macrophages towards the M2 phenotype, as demonstrated by an increased mRNA expression of Retnla, Arg1, and Chil3 in cells from mice exposed to 0.5 or 1 Gy compared with non-irradiated animals. Minimal effects were noted in M1 cells or M1 marker mRNA. Concurrently, we observed a reduced secretion of IL-1β but enhanced IL-10 release from M0 and M2 macrophages. Effects of irradiation on circulating monocytes were most marked at day 10 post-exposure, when the 1 Gy dose was associated with enhanced numbers of both Ly6C High and Ly6 Low cells. By day 100, levels of circulating monocytes in irradiated and non-irradiated mice were equivalent, but anti-inflammatory Ly6C Low monocytes were significantly increased in the spleen of mice exposed to 0.05 or 1 Gy. Long term exposures did not affect atherosclerotic plaque size or lipid content, as determined by Oil red O staining, whatever the dose applied. Similarly, irradiation did not affect atherosclerotic plaque collagen or smooth muscle cell content. However, we found that lesion CD68+ cell content tended to decrease with rising doses of radioactivity exposure, culminating in a significant reduction of plaque macrophage content at 1 Gy. Taken together, our results show that short- and long-term exposures to low to moderate doses of ionizing radiation drive an anti-inflammatory response, skewing bone marrow-derived macrophages towards an IL-10-secreting M2 phenotype and decreasing plaque macrophage content. These results suggest a low-grade athero-protective effect of low and moderate doses of ionizing radiation
Temporal evolution of plastic additive contents over the last decades in two major European rivers (Rhone and Rhine) from sediment cores analyses
No full text(IF 7.6;Q1)International audienceAlthough global plastic distribution is at the heart of 21st century environmental concerns, little information is available concerning how organic plastic additives contaminate freshwater sediments, which are often subject to strong anthropogenic pressure. Here, sediment core samples were collected in the Rhone and the Rhine watersheds (France), dated using 137Cs and 210Pbxs methods and analysed for nine phthalates (PAEs) and seven organophosphate esters (OPEs). The distribution of these organic contaminants was used to establish a chronological archive of plastic additive pollution from 1860 (Rhine) and 1930 (Rhone) until today. Sediment grain size and parameters related to organic matter (OM) were also measured as potential factors that may affect the temporal distribution of OPEs and PAEs in sediments. Our results show that OPE and PAE levels increased continuously in Rhone and Rhine sediments since the first records. In both rivers, ∑PAEs levels (from 9.1 ± 1.7 to 487.3 ± 27.0 ng g−1 dry weight (dw) ± standard deviation and from 4.6 ± 1.3 to 65.2 ± 11.2 ng g−1 dw, for the Rhine and the Rhone rivers, respectively) were higher than ∑OPEs levels (from 0.1 ± 0.1 to 79.1 ± 13.7 ng g−1 dw and from 0.6 ± 0.1 to 17.8 ± 2.3 ng g−1 dw, for Rhine and Rhone rivers, respectively). In both rivers, di(2-ethylhexyl) phthalate (DEHP) was the most abundant PAE, followed by diisobutyl phthalate (DiBP), while tris (2-chloroisopropyl) phosphate (TCPP) was the most abundant OPE. No relationship was found between granulometry and additives concentrations, while organic matter helps explain the vertical distribution of PAEs and OPEs in the sediment cores. This study thus establishes a temporal trajectory of PAEs and OPEs contents over the last decades, leading to a better understanding of historical pollution in these two Western European rivers
A High-Resolution Portable Gamma-Camera for Estimation of Absorbed Dose in Molecular Radiotherapy
No full textInternational audienceMolecular radiotherapy is a treatment modality that requires personalized dosimetry for efficient treatment and reduced toxicity. Current clinical imaging systems and miniaturized gamma-cameras lack the necessary features for this task. In this article, we present the design and optimization of a mobile gamma-camera with a 10×10 cm2 field of view tailored for quantitative imaging during 131I therapy of thyroid diseases. The camera uses a monolithic 10×10×1 cm3 CeBr3 scintillator coupled to a 16×16 SiPMs array and commercial electronics. It exhibits high imaging performance with an intrinsic spatial resolution (SR) of 1.15-mm FWHM, an energy resolution of 8% FWHM at 356 keV and negligible deadtime up to 150 kcps. Images are reconstructed in real time using a convolutional neural network. The manufacturing method of tungsten collimators and shielding was optimized using laser 3-D printing to achieve an effective density of 97% that of bulk tungsten. Their geometry was adjusted with Monte-Carlo simulations in order to reduce septal penetration and scattering and optimize the signal-to-noise ratio at short times after treatment administration. Two high-energy parallel-hole collimators with high sensitivity or very high SR were designed for treatment planning and post-treatment control. The fully operational gamma-camera will soon be clinically assessed
The European intercomparison of in-vivo monitoring laboratories: the EIVIC-2020 project
No full textInternational audienceThe EIVIC project was launched in 2020, and the main goal was the organisation of a European intercomparison of in-vivo monitoring laboratories dealing with direct measurements of gamma-emitting radionuclides incorporated into the body of exposed workers. This project was organised jointly by members of EURADOS Working Group 7 on internal dosimetry (WG7), the Federal Office for Radiation Protection (BfS, Germany) and the Radioprotection and Nuclear Safety Institute (IRSN, France). The objective was to assess the implementation of individual-monitoring requirements in EU Member States on the basis of in-vivo measurements and to gain insight into the performance of in-vivo measurements using whole-body counters. In this context, a total of 41 in-vivo monitoring laboratories from 21 countries, together with JRC (EC) and IAEA participated. The results were submitted in terms of activity (Bq) of the radionuclides identified inside phantoms that were circulated to all participants. The measured data were compared with reference activity values to evaluate the corresponding bias according to the standards ISO 28218 and ISO 13528. In general, the results of the different exercises are good, and most facilities ar e in conformity with the criteria for the bias and z-scores in the ISO standards. Furthermore, information about technical and organisational characteristics of the participating laboratories was collected i n order to test if they had a significant influence on the reported results
Joint EURADOS-EANM initiative for an advanced computational framework for the assessment of external dose rates from nuclear medicine patients
No full textInternational audienceAbstract Background In order to ensure adequate radiation protection of critical groups such as staff, caregivers and the general public coming into proximity of nuclear medicine (NM) patients, it is necessary to consider the impact of the radiation emitted by the patients during their stay at the hospital or after leaving the hospital. Current risk assessments are based on ambient dose rate measurements in a single position at a specified distance from the patient and carried out at several time points after administration of the radiopharmaceutical to estimate the whole-body retention. The limitations of such an approach are addressed in this study by developing and validating a more advanced computational dosimetry approach using Monte Carlo (MC) simulations in combination with flexible and realistic computational phantoms and time activity distribution curves from reference biokinetic models. Results Measurements of the ambient dose rate equivalent Ḣ * (10) at 1 m from the NM patient have been successfully compared against MC simulations with 5 different codes using the ICRP adult reference computational voxel phantoms, for typical clinical procedures with 99m Tc-HDP/MDP, 18 FDG and Na 131 I. All measurement data fall in the 95% confidence intervals, determined for the average simulated results. Moreover, the different MC codes (MCNP-X, PHITS, GATE, GEANT4, TRIPOLI-4 ® ) have been compared for a more realistic scenario where the effective dose rate Ė of an exposed individual was determined in positions facing and aside the patient model at 30 cm, 50 cm and 100 cm. The variation between codes was lower than 8% for all the radiopharmaceuticals at 1 m, and varied from 5 to 16% for the face-to face and side-by-side configuration at 30 cm and 50 cm. A sensitivity study on the influence of patient model morphology demonstrated that the relative standard deviation of Ḣ * (10) at 1 m for the range of included patient models remained under 16% for time points up to 120 min post administration. Conclusions The validated computational approach will be further used for the evaluation of effective dose rates per unit administered activity for a variety of close-contact configurations and a range of radiopharmaceuticals as part of risk assessment studies. Together with the choice of appropriate dose constraints this would facilitate the setting of release criteria and patient restrictions
Review of the PRIODAC project on thyroid protection from radioactive iodine by repeated iodide intake in individuals aged 12+
No full textInternational audienceBackground Intake of potassium iodide (KI) reduces the accumulation of radioactive iodine in the thyroid gland in the event of possible contamination by radioactive iodine released from a nuclear facility. The World Health Organization (WHO) has stated the need for research for optimal timing, appropriate dosing regimen, and safety for repetitive iodine thyroid blocking (ITB). The French PRIODAC project, addressed all these issues, involving prolonged or repeated releases of radioactive iodine. Preclinical studies established an effective dose through pharmacokinetic modeling, demonstrating the safety of repetitive KI treatment without toxicity. Summary Recent preclinical studies have determined an optimal effective dose for repetitive administration, associated with pharmacokinetic modeling. The results show the safety and absence of toxicity of repetitive treatment with KI. Good laboratory practice level preclinical studies corresponding to individuals >12 years have shown a safety margin established between animal doses without toxic effect. After approval from the French health authorities, the market authorization of the two tablets of KI, 65 mg/day, was defined with a new dosing scheme of a daily repetitive intake of the treatment up to 7 days unless otherwise instructed by the competent authorities for all categories of population except pregnant women and children under the age of 12 years. Conclusion This new marketed authorization resulting from scientific-based evidence obtained as part of the PRIODAC project may serve as an example to further harmonize the application of KI for repetitive ITB in situations of prolonged radioactive release at the European and international levels, under the umbrella of the WHO .(C2VN), Institut national de recherche pour l'agriculture, l'alimentation et l'environnement (INRAE)
A MODEL FOR FINELY, INTRICATE, RANDOM MULTIPHASE SYSTEMS
No full textA multiphase system is said fine for a given scale of observation if its phases are scattered in a large number of individual space domains within a unit of volume corresponding to the observation scale. In the same way, the system is said fine with regard to time if, at a given point, phases alternate very often during the time unit corresponding to the observation time scale. In addition, when time and space distributions of the phases does not present repetitive or periodic patterns, the system is said a finely intricate one. Finally, if intricacy results of the random distributions both in time and space of the phase domains, such systems are defined as Finely Intricate Random Multiphase (FIRM) systems. Canopies are simple and common ordinary FIRM multiphase systems. In forests, the air flows through canopies where the leaves are a second phase. An important practical question is the airborne particle deposition rates by time and volume units (let us say a few minutes and a cubic meter) on several hundred leaves which are ruffled by coupling with the turbulent air flow. Let us assume that all the le local instantaneous quantities required for describing a FIRM system are available. Let us assume that they obey the basic law of physics, and then both balance equations for each phase and transfer equations for their exchanges are available. Assuming we are able to solve such a set of equations, we obtain the behaviour of the system. But, the solutions will be intractable and useless because the amount of data required to describe the local instantaneous values of these quantities will be so huge that it will prevents any one from deriving understandable information directly from them. Then, how to proceed? First, we retain the idea to write down the set of basic balance and transfer equations for the local and instantaneous quantities. Two, instead to handle directly this set, we modify it using weighting operators in such a way to obtain new balance equations for weighted quantities. The reason for such a procedure is the following. Local equations are defined only where and when a phase is present and we know that such space time domains can be highly variable for FIRM systems. On the contrary, balance equations for the weighted quantities are defined at any point and instant. They provide a way to describe the behavior of these systems. Here after, starting from the balance equations of the local and instantaneous quantities, the FIRM model development provides balance equations for global quantities which are valid everywhere at the scale of interest for applications. A following paper will provide applications of this model to forest canopy and sea
Metrology supporting the European regulation for radiation protection
No full textInternational audienceThe European Association of National Metrology Institutes (EURAMET) within its research programme European Metrology Programme for Innovation and Research (EMPIR) funded project EMPIR 19NET03 supportBSS that contributes to the establishment of a European Metrology Network (EMN) for Radiation Protection (RP). The EMN-RP was established in September 2021 with the intent to work as a meeting point for the metrology community and all stakeholders in the field of ionising radiation regulation, thus providing quality assurance for measurements in each of the exposure situations contemplated in the European Legislation. Within project EMPIR 19NET03, work package 3 aims at the preparation of a Strategic Research Agenda (SRA) by identifying the metrology needs to support the European legislation and regulation in Radiation Protection and of two Roadmaps for metrology services, one under the European Council Directive 2013/59/EURATOM and the other under the EURATOM Treaty. Following a Gaps Workshop held in September 2020 and a second internal workshop that took place in April 2022, a questionnaire was prepared for distribution to the stakeholders, e.g. RP platforms and authorities, academia, industry, among other, together with an accompanying paper. In this paper, the authors present the state of the art of European legislation in RP, address the importance of metrology, the practices and activities that need metrology to meet the requirements set in the regulations, emphasise the need for quality assured measurements in all fields, highlight the stakeholders contributions in their specific area and show their vision of the EMN-RP