Mise en oeuvre d’un démonstrateur de caméra Compton pour l’imagerie en médecine nucléaire et pour le contrôle en temps réel de l’hadronthérapie à l’aide des rayonnements gamma prompts

摘要

Hadrontherapy is one of the modalities available for treating cancer. This modality uses light ions (protons, carbon ions) to destroy cancer cells. Such particles have a ballistic accuracy thanks to their quasi-rectilinear trajectory, their path and the finished profile maximum dose in the end. Compared to conventional radiotherapy, this allows to spare the healthy tissue located adjacent downstream and upstream of the tumor. One of this modality’s quality assurance challenges is to control the positioning of the dose deposited by ions in the patient. One possibility to perform this control is to detect the prompt gammas emitted during nuclear reactions induced along the ion path in the patient. A Compton camera prototype, theoretically allowing to maximize the detection efficiency of the prompt gammas, is being developed under a regional collaboration. This camera was the main focus of my thesis, and particularly the following points : i) studying, throughout Monte Carlo simulations, the operation of the prototype in construction, particularly with respect to the expected counting rates on the different types of accelerators in hadrontherapy ii) conducting simulation studies on the use of this camera in clinical imaging, iii) characterising the silicon detectors (scatterer) iv) confronting Geant4 simulations on the camera’s response with measurements on the beam with the help of a demonstrator. As a result, the Compton camera prototype developed makes a control of the localization of the dose deposition in proton therapy to the scale of a spot possible, provided that the intensity of the clinical proton beam is reduced by a factor 200 (intensity of 108 protons / s). An application of the Compton camera in nuclear medicine seems to be attainable with the use of radioisotopes of an energy greater than 300 keV. These initial results must be confirmed by more realistic simulations (homogeneous and heterogeneous PMMA targets). Tests with the progressive integration of all camera elements will take place during 2016