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Cassures double-brin de l’ADN et influence du facteur individuel dans la réponse aux faibles doses de radiation : cas particulier des examens par scanner

Abstract : Low doses of radiation are an important societal issue, particularly for risk estimation potentially associated with medical exposures. Indeed, the dose delivered during diagnostic radiology examinations has more than doubled in 10 years. However, the evaluation of the radiation-induced risk is difficult due to the variety of irradiation protocols (dose per session, cumulative dose, dose rate, type of radiation), the lack of dosimeter sensitivity and the lack of knowledge of the specific biological effects of low doses such as low dose hypersensitivity (HRS), adaptive response (AR) and hormesis. In addition, it now appears that the individual factor can significantly influence the biological and clinical response to radiation. In this thesis, in order to better assess the individual risk related to low doses of radiation in the frame of computed tomography exposure, we have combined the knowledge of two structures: the Fibermetrix company, which provides a new technology of physical dosimeters based on optical fiber, and the Inserm UA8 Unit "Radiations : Defense, Health, Environment", whose RIANS model developed on human data now make possible to better understand specific radiobiological effects. We exposed a collection of human fibroblasts, astrocytes and mammary epithelial cells in exact CT conditions (head or chest CT examinations), using DNA double-strand break (DSB) repair and signaling biomarkers. Besides, we proposed a mechanistic model based on nucleo-shuttling of the ATM protein from the cytoplasm to the nucleus in order to explain the three specific radiobiological effects of low doses (HRS, RA and hormesis). The immunofluorescence analysis of data from CT exposures shows an excess of DSB for radiosensitive or predisposed to cancer patient. Fibermetrix IVISCAN device allowed for more accurate dose assessment. This approach resulted in a risk assessment for each condition tested, a definition of genetic risk status for low doses and recommendations on how to perform risk analyses of irradiated patients
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Submitted on : Monday, July 5, 2021 - 4:39:09 PM
Last modification on : Wednesday, November 3, 2021 - 4:35:10 AM
Long-term archiving on: : Wednesday, October 6, 2021 - 9:17:44 PM


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  • HAL Id : tel-03278539, version 1



Clément Devic. Cassures double-brin de l’ADN et influence du facteur individuel dans la réponse aux faibles doses de radiation : cas particulier des examens par scanner. Biologie cellulaire. Université de Lyon, 2020. Français. ⟨NNT : 2020LYSE1094⟩. ⟨tel-03278539⟩



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