Datation par luminescence (recherches méthodologiques et applications au volcanisme dans l'environnement de Laschamp)

L'objectif de ce travail était de dater des coulées volcaniques de la Chaîne des Puys (Massif Central, France) situées chronologiquement dans la période de l'événement paléomagnétique de Laschamp (30-50 ka). Les méthodes utilisées étaient la thermoluminescence et la luminescence stimulée optiquement appliquées à des grains de quartz et à des galets quartzeux extraits de sédiments cuits par ces coulées. Ces minéraux émettent des signaux de luminescence dont le comportement est souvent irrégulier. Leur paléodose a donc été déterminée par différentes méthodes pour choisir celles qui seraient les plus appropriées à l'obtention de résultats fiables. Ces intercomparaisons ont mis en évidence une dispersion des résultats supérieure à ce qui pouvait être attendu au regard des incertitudes habituellement associées à chacune d'entre elles. Dans la plupart des cas, ces observations ont conduit à proposer un intervalle assez large dans lequel est compris l'âge probable de l'échantillonCLERMONT FD-BCIU Sci.et Tech. (630142101) / SudocSTRASBOURG-Bib.Central Recherche (674822133) / SudocSudocFranceF

OSL signal of electronic components from portable radios for radiation accident dosimetry

International audienceWhen a radiological accident occurs, the dose absorbed by the victims must be assessed quickly and accurately in order to select an appropriate medical treatment. In emergency situations where radiological risk has not been immediately identified, first responders from the homeland security forces are rarely equipped with a personal dosimeter. In the absence of conventional dosimetric data, materials found on or near them could be used as fortuitous retrospective dosimeters to estimate the dose received. Since the general population almost always carries a mobile phone, the materials from those items have been extensively studied, especially with luminescence methods. For example, protocols using Optically Stimulated Luminescence (OSL) of resistors removed from their circuit board were developed. For homeland security forces, the preferred mean of communication is the portable radio. This device is systematically carried during intervention and could be a fortuitous dosimeter of choice if containing electronic components with similar dosimetric properties. In this work, portable radios used by a French specialised intervention unit were studied. Many resistors were observed on the circuit boards of those portable radios. Their size was larger than that of resistors from mobile phones. Their main dosimetric properties (sensitivity, measurement reproducibility, dose response, signal stability…) were investigated by OSL and compared to those of resistors extracted from mobile phones. These results, as well as those of dose recovery tests, will be presented. In addition, portable radios may be subjected to various constraints when used on the field and in particular the temperature which can considerably vary. The influence of this parameter on the OSL signal will be discussed

Feasibility study of using earbuds and wireless headphones for retrospective dosimetry

International audienceLuminescence dosimetry could be an essential tool in retrospective dosimetry for assessing an absorbed dose after a radiological overexposure. Mobile phone components could be useful proxies for measuring the amount of dose an individual has received. Different research groups have extensive experience in characterising different elements of mobile phones (i.e. electronic components, display or touch screen glass) for physical retrospective dosimetry. However, so far these techniques are frequently destructive and alternative materials need to be sought for further research on cheaper electronic devices. Earbuds and wireless headphones have become quite popular and are often carried closely to the body or may be found in personal bags. These low-budget electronic devices might potentially be better accepted by the general population compared to high-price objects, such as an expensive smartphone. On the circuit boards of these items, electronic components (SMDs) were found. The results of a dose recovery test after x-ray irradiation using a standardized luminescence measurement protocol developed for resistors extracted from mobile phones are presented. The estimated doses from the sampled SMDs were overestimated by a factor up to 2.1 following this initial experiment. Further investigations showed that the signal stability of some SMDs was significantly different from that of mobile phone resistors. The use of a fading correction specific to these SMDs improved the dose reconstruction results. Generally, these low-budget electronic devices are potentially suitable for dose assessment and an alternative fortuitous retrospective dosimeter

A TL study of protective glasses of mobile phones for retrospective dosimetry

Several studies have shown that certain components of mobile phones, such as electronic components, display or touch screen glass, are suitable as emergency dosimeters in case of radiological incidents. However, so far the methods are frequently destructive and in case of a dose assessment the mobile phone will be destroyed. In order to overcome this problem, alternative materials need to be sought and further research is necessary. Building on results of a previous study, we further investigated protective glasses in this work, which have become an alternative material for dose reconstruction. Protective glasses are easy to sample and cheap, have become very popular to protect the surface of phones, can be easily replaced without complete destruction of an expensive smartphone, thus a dose assessment method based on this material will potentially find much greater public acceptance. The aim of this study was to optimize the detection window by systematically investigating the radiation-induced TL signals and intrinsic zero dose signals. Using two selected detection windows, the long-term and optical stability of the TL signals were investigated. The set of nine different protective glass samples studied fell into two groups with different fading and optical bleaching characteristics. Further research is necessary in order to reduce the zero dose signal, to reinvestigate the dosimetric properties and to verify the final protocol using a realistic irradiation test

Mobile phone screen protector glass: A TL investigation of the intrinsic background signal

International audienceScreen protector glasses are often used to protect the display screen surfaceof mobile phones against physical damage. Their dosimetric properties wererecently studied by thermoluminescence with the aim of using these itemsas potential emergency dosimeters in the event of a radiological accident.They are sensitive to ionizing radiation and they could be easily removed andreplaced without destroying the phone in case of a dose assessment. However,an intrinsic background signal that partially overlaps with the radiation-inducedTL signal is observed. The reconstructed dose could be overestimated ifnot properly taken into account. The homogeneity of this confoundingsignal on the surface of several screen protectors was estimated and achemical treatment with hydrofluoric acid (HF 40%) was tested to minimizeits contribution. For most of the samples studied, the intrinsic backgroundsignal remained a serious issue for dose reconstruction. Additionally, the TLsignals were measured in the red detector range using two different modelsof red-sensitive photomultiplier tubes. The homogeneity of the intrinsicbackground signal on the surface of screen protectors was examined andthe results of the reduction of this signal by the chemical HF treatmentwere discussed

Violet stimulated luminescence signal from electronic components for radiation accident dosimetry

International audienceDue to recent technological advances, new optical stimulation sources with higher energies became commercially available. In the present work, laser diodes emitting in the violet (∼405 nm) were used to investigate dosimetric characteristics of the violet stimulated luminescence (VSL) signal from electronic components (resistors and inductors) extracted from mobile phones. All component types exhibit higher sensitivity using violet stimulation than using blue one. The sensitization was negligible after 10 cycles of irradiation and measurement. The dose response was linear from 0.6 Gy to 30 Gy. Additionally, signal fading of one type of inductors was studied. Results were similar for blue stimulated luminescence (BSL) and VSL signals. Fading measurements performed at 40 °C after a preheat (125 °C hold for 10 s) or at 125 °C indicated low fading rates (∼95% of signal remaining 1 h after irradiation). These preliminary results appear to be promising for retrospective dosimetry

Radioiodine therapy for thyroid cancer and dysfunction of the salivary and lachrymal glands in the START study: results at 6 months follow-up

International audienceBackgroundUnderstanding of changes in salivary and lachrymal gland functions after radioiodine therapy (131I-therapy) remains limited; and, to-date no studies have evaluated dose-response relationships between absorbed dose from 131I-therapy and dysfunctions of these glands. This study investigates salivary/lachrymal dysfunctions in differentiated thyroid cancer (DTC) patients six months after 131I-therapy, identifies 131I-therapy related risk factors for salivary/lachrymal dysfunctions, and assesses the relationships between 131I-therapy radiation dose and these dysfunctions.MethodsA study was conducted involving 136 DTC patients treated by 131I-therapy of whom 44 and 92 patients received 1.1 and 3.7 GBq, respectively. Absorbed dose to the salivary glands was estimated using a dosimetric reconstruction method based on thermoluminescent dosimeters measurements. Salivary and lachrymal functions were assessed at baseline (T0, i.e., immediately prior to 131I-therapy), and 6 months later (T6) using validated questionnaires and salivary samplings, with and without stimulation of the salivary glands. Statistical analyses included descriptive analyses and random-effects multivariate logistic and linear regressions.ResultsThere was no difference between T0 and T6 in the level of parotid gland pain, nor was there difference in the number of patients with hyposalivation, but there were significantly more patients with dry mouth sensation and dry eyes after therapy compared to baseline. Age, menopause, depression and anxiety symptoms, history of systemic disease, and not taking painkillers in the last 3 months were found to be significantly associated with salivary or lachrymal disorders. Significant associations were found between 131I-exposure and salivary disorders adjusted on the previous variables: e.g. per 1-Gy increase in mean dose to the salivary glands, OR=1.43 (95%CI 1.02-2.04) for dry mouth sensation, ß=-0.08 (95%CI -0.12;-0.02) mL/min for stimulated saliva flow, and ß= 1.07 (95%CI 0.42;1.71) mmol/L for salivary potassium concentration. Conclusions This study brings new knowledge on the relationship between the absorbed dose to the salivary glands from 131I-therapy and salivary/lachrymal dysfunctions in DTC patients 6 months after 131I-therapy. Despite the findings of some dysfunctions, the results do not show any obvious clinical disorders after the 131I-therapy. Nevertheless, by identifying risk factors, this study encourages clinicians to adapt the therapy for patients at risk of salivary/lachrymal complications

Overview of physical dosimetry methods for triage application integrated in the new European network RENEB

International audienceOver the last years, the risk of a large scale radiological event has markedly increased. This includes possible accidents in nuclear facilities but also potential terrorist attacks against key facilities or civil targets. In both contexts, retrospective dosimetry is an essential tool to estimate an actual absorbed dose. Thus, individuals, who need extensive medical care due to severe irradiation can be identified among people who have not received high doses of ionizing radiation. In such large-scale radiological scenarios the capacity of single or few retrospective dosimetry laboratories will be overcharged . As a consequence networking has been recognized as a sensible and important element of emergency response strategy. Now a European Network of retrospective dosimetry is on the way to being realized. In addition of biodosimetry techniques, retrospective dosimetry techniques such EPR spectroscopy or luminescence has been considered. These techniques are applied on materials found in mobile phones (LCD glass, touch screen, electronic components) providing possibility of a dose estimation for a large part of the population

Dysfunction of the salivary and lacrimal glands after radioiodine therapy: 6-month follow-up results of a self-controlled study in France

Abstract: Following radioiodine therapy (RAI) of differentiated thyroid cancer, salivary and lacrimal glands may be injured, leading to dysfunctions. The incidence of these dysfunctions after RAI is poorly known, and no risk factors have been identified to date to define at-risk patients. The aims of this study are to characterize the dysfunction of salivary and lacrimal glands after RAI, and to identify risk factors of such dysfunctions.START (Salivary dysfuncTion After Radioiodine Treatment) is a prospective study launched in 2020, including 139 thyroid cancer patients, candidates for a RAI (45 and 94 patients received 1.1GBq and 3.7GBq 131I activity, respectively) in Pitié-Salpêtrière hospital, Paris, France. Follow-up was based on 3 scheduled visits: immediately before RAI (T0), 6 months (T6) and 18 months (T18) later. At each visit, questionnaires on salivary disorders (validated French tool), dry eye (OSDI© Questionnaire), and anxiety/depression symptoms (HAD scale) were administered. At T0 and T6, individual salivary flow measurements (with and without salivary gland stimulation) were performed. The doses to the salivary glands were evaluated through a dosimetric reconstruction based on recordings from thermoluminescent dosimeters directly positioned on the patients. In the present work, data for the T0 and T6 visits were analysed based on descriptive analyses and random-effects logistic and linear regressions.Complete information was provided for 136 patients (71% women, mean age=47.1 (±14.1) y). Mean doses to the salivary glands were 0.7 (±0.2) and 2.3 (±0.9) Gy for the 1.1GBq and 3.7GBq 131I-activity groups, respectively. At T6, 18% and 22% of the study population without any symptoms at T0 reported dry eye and/or dry mouth feeling, respectively. Stimulated saliva flow rate significantly decreased from T0 to T6 (2.14 (±0.86) and 1.93 (±0.78) mL/min, p<10-3, respectively). Univariate analyses allowed to highlight age, menopause, depression and anxiety symptoms, history of systemic disease, and not taking painkillers in the last 3 months as risk factors or variables significantly associated with salivary or lachrymal disorders. Multivariate analyses adjusted on the previous variables showed significant dose-responses relationships between doses to the salivary glands and dry mouth sensation or stimulated saliva flow rate, as well as between administered activity and dry mouth sensation or lachrymal disorders. This work presents the 6 months follow-up results of the START study, showing higher salivary and lacrimal gland disorders after RAI. Further analyses will include saliva biochemical concentrations, genetic and epigenetic variants as risk factors, and quality of life of patients at T6 and T18