Réalisation d un mannequin anthropomorphe pourvu de détecteurs afin d évaluer la dose efficace aux postes de travail soumis à des champs photoniques (étude expérimentale)

Le travail de thèse se propose d étudier la faisabilité pratique de la réalisation de cet instrument d expertise qui sera utilisé par le Laboratoire de Dosimétrie des Rayonnements Ionisants pour l étude des postes en radioprotection. Le travail se divise en deux aspects principaux : le premier concerne, le système de dosimétrie dont les détecteurs seront insérés dans le mannequin et le deuxième étudie (par simulation à l aide d un code de calcul Monte Carlo) les précisions des estimations de E pour différentes configurations d irradiation que l on pourrait obtenir avec notre instrument de mesure, en prenant en considération toutes les contraintes expérimentales. La caractérisation du détecteur a permis d obtenir une mesure de la dose approchant à +-30 % la dose déposée dans le tissu-mou dont est constitué le mannequin pour la gamme d énergie entre 60 keV et 4 MeV. Les simulations numériques Monte Carlo, ont été réalisées à partir de la voxelisation d un mannequin physique existant dans lequel ont été modélisés les capteurs placés aux positions déterminées lors de l étude théorique, adaptées à notre géométrie. Ainsi, pour des irradiations homogènes, hétérogènes et typiques d un poste de travail, le mannequin instrumenté permettrait l estimation de la dose efficace E à +-25 % pour la gamme d énergie de 50 keV à 4 MeV. La plus value du mannequin instrumenté sur la précision de l estimation de E a été démontrée par comparaison aux valeurs obtenus pour l équivalent de dose individuel Hp(10) pour les configurations étudiées.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Dosimetric characterization of a small-scale (Zn,Cd)S:Ag inorganic scintillating detector to be used in radiotherapy

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High resolution small‐scale inorganic scintillator detector: HDR brachytherapy application

International audiencePurpose: Brachytherapy (BT) deals with high gradient internal dose irradiation made up of a complex system where the source is placed nearby the tumor to destroy cancerous cells. A primary concern of clinical safety in BT is quality assurance to ensure the best matches between the delivered and prescribed doses targeting small volume tumors and sparing surrounding healthy tissues. Hence, the purpose of this study is to evaluate the performance of a point size inorganic scintillator detector (ISD) in terms of high dose rate brachytherapy (HDR-BT) treatment. total signal in all the irradiations. Excellent symmetrical behavior of the dose rate regarding source position was observed at different radiation planes. Finally, a comparison with TG-43 reference dataset shows that corrected measurements agreed with simulation data within 1.2% and 1.3%, and valid for the source-to-detector distance greater than 0.25 cm. Conclusion: The proposed ISD in this study anticipated that the system could be promoted to validate with further clinical investigations. It allows an appropriate dose verification with dwelltime estimation during source tracking and suitable dose measurement with a high spatial resolution both nearby (high dose gradient) and far (low dose gradient) from the source position

Repeated Multimodality Ablative Therapies for Oligorecurrent Pulmonary Metastatic Disease

Stereotactic body radiotherapy (SBRT) and percutaneous thermal ablation (TA) are alternatives to surgery for the management of pulmonary oligometastases. In this collaborative work, we retrospectively analyzed patients who had undergone iterative focal ablative treatments of pulmonary oligometastases. We hypothesized that repeated ablative therapies could benefit patients with consecutive oligometastatic relapses. Patients treated with SBRT and/or TA for pulmonary oligometastases in two French academic centers between October 2011 and November 2016 were included. A total of 102 patients with 198 lesions were included; 45 patients (44.1%) received repeated focal treatments at the pulmonary site for an oligorecurrent disease (the “multiple courses” group). Median follow-up was 22.5 months. The 3-year overall survival rates of patients who had a single treatment sequence (the “single course” group) versus the “multiple courses” were 73.9% and 78.8%, respectively, which was not a statistically significant difference (p = 0.860). The 3-year systemic therapy-free survival tended to be longer in the “multiple courses” group (50.4%) than in the “single course” group (44.7%) (p = 0.081). Tolerance of repeated treatments was excellent with only one grade 4 toxicity. Thereby, multimodality repeated ablative therapy is effective in patients with pulmonary oligorecurrent metastases. This strategy may delay the use of more toxic systemic therapy

Health-related quality of life in locally advanced hepatocellular carcinoma treated by either radioembolisation or sorafenib (SARAH trial)

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