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Other titre : Évaluation du potentiel radiosensibilisateur ou radioprotecteur/antioxydant de quelques composés sélectionnés par dosimétrie par gel de polyacrylamide et dosimètre de Fricke, et utilisation de la filamentation par impulsion laser infrarouge femtoseconde comme un nouveau et puissant faisceau pour la radiothérapie du cancer

dc.contributor.advisorLepage, Martinfr
dc.contributor.authorMeesat, Ridtheefr
dc.date.accessioned2015-02-23T19:22:08Z
dc.date.available2015-02-23T19:22:08Z
dc.date.created2012fr
dc.date.issued2012fr
dc.identifier.urihttp://hdl.handle.net/11143/6246
dc.description.abstractIn radiation treatment, a sufficiently high radiation dose must be delivered to the tissue volumes containing the tumor cells while the lowest possible dose should be deposited in surrounding healthy tissue. We developed an original approach that is fast and easy to implement for the early assessment of the efficiency of radiation sensitizers and protectors. In addition, we characterized a new femtosecond laser pulse irradiation technique. We are able to deposit a considerable dose with a very high dose rate inside a well-controlled macroscopic volume without deposition of energy in front or behind the target volume. The radioprotective efficiency was measured by irradiation of the Fricke solution incorporating a compound under study and measuring the corresponding production of ferric ions G (Fe3+ ). The production of ferric ions is most sensitive to the radical species produced in the radiolysis of water. We studied experimentally and simulated with a full Monte-Carlo computer code the radiation-induced chemistry of Fricke/cystamine solutions. Results clearly indicate that the protective effect of cystamine originates from its radical-capturing ability, which allows this compound to compete with the ferrous ions for the various fre radicals - especially · OH radicals and H· atoms - formed during irradiation of the surrounding water. The sensitizing capacity of radiation sensitizers was measured by irradiation of a polyacrylamide gel (PAG) dosimeter incorporating a compound under study and measuring the corresponding increase in the gradient between spin-spin relaxation rate (R2 ) and absorbed dose. We measured an irradiation energy-dependent increase in R 2 -dose sensitivity for halogenated compounds or a decrease for radioprotectors. Finally, we studied a novel laser irradiation method called "filamentation". We showed that this phenomenon results in an unprecedented deposition of energy and the dose rate thus achieved exceeds by orders of magnitude values previously reported for the most intense clinical radiotherapy systems. Moreover, the length of the dose-fre entrance region was adjusted by selecting the duration of femtosecond laser pulses. In addition, we provided evidence that the biological damage caused by this irradiation was similar to other ionizing radiation sources. [symboles non conformes]fr
dc.language.isoengfr
dc.publisherUniversité de Sherbrookefr
dc.rights© Ridthee Meesatfr
dc.subjectDosimetryfr
dc.subjectFilamentationfr
dc.subjectLaserfr
dc.subjectRadioprotectionfr
dc.subjectRadiosensitizationfr
dc.subjectRadiotherapyfr
dc.titleEvaluation of the radiosensitizing or radioprotective/antioxidant potential of some selected compounds by polyacrylamide gel dosimetry and Fricke dosimeter, and utilization of the femtosecond infrared laser pulse filamentation as a novel, powerful beam for cancer radiotherapyfr
dc.title.alternativeÉvaluation du potentiel radiosensibilisateur ou radioprotecteur/antioxydant de quelques composés sélectionnés par dosimétrie par gel de polyacrylamide et dosimètre de Fricke, et utilisation de la filamentation par impulsion laser infrarouge femtoseconde comme un nouveau et puissant faisceau pour la radiothérapie du cancerfr
dc.typeThèsefr
tme.degree.disciplineSciences des radiations et imagerie biomédicalefr
tme.degree.grantorFaculté de médecine et des sciences de la santéfr
tme.degree.levelDoctoratfr
tme.degree.namePh.D.fr


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