Détermination de l'incidence de l'ajout d'un fluorophore à l'eau sur la dosimétrie Cherenkov en radiothérapie externe

Authors: Jean, Emilie
Advisor: Beaulieu, Luc
Abstract: Particles traveling through a medium at a speed exceeding light speed in that same medium gives rise to a phenomenon of photon emission. This phenomenon, called the Cherenkov effect, can be used to determine the dose deposition in a water phantom from a linear accelerator used in external radiotherapy. However, Cherenkov effect produces an anisotropic emission which makes the calculation of the dose complex as the relation between the dose deposition and the intensity of the signal collected is not linear. An alternative recently proposed consist of adding a fluorescent agent to the water with the hypothesis that it can absorb the Cherenkov emission and reemit it as an isotropic fluorescent light. To evaluate the efficiency of this method, the present study aims to determine the contribution of each excitation source producing the total light signal measured in the visible range during the irradiation of an aqueous quinine solution. Moreover, it aims to quantify the Cherenkov light absorption by the fluorophore in the UV region. To achieve this, various concentrations of aqueous quinine solutions were irradiated with a linear accelerator and the spectra where collected with a spectrometer. To determine the initial Cherenkov light production in the solvent, a control sample of distilled water was irradiated under the same conditions as the fluorophore solutions. Furthermore, using the light signal collected by a CCD camera, a comparison between the dose deposition along the beam path was performed between the quinine solution and the pure Cherenkov light. It was then possible to compare the percent depth dose obtained with both solution with a treatment planning system dose calculation to determine how quinine improves measurements.
Document Type: Mémoire de maîtrise
Issue Date: 2019
Open Access Date: 7 August 2019
Permalink: http://hdl.handle.net/20.500.11794/35846
Grantor: Université Laval
Collection:Thèses et mémoires

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