Development of a Beam Tagging Diamond Hodoscope for Online Ion Range Verification in Hadrontherapy

International audienceHadrontherapy enables a highly localized dose deposition and better organ-at-risk protection, compared to conventional photon radiotherapy. Therefore, the treatment quality strongly relies on the control of the effective ion range in vivo. However, the ballistics makes this technique sensitive to various ion range uncertainties induced by the dose calculation, patient set-up and morphological changes between sessions. In this context, the French CLaRyS collaboration aims to develop various online ion range verification techniques by detecting secondary particles emitted by the patient following nuclear interactions along the ion path. Among them, Prompt-Gamma Imaging consists in the detection of gamma rays by either a collimated- or a Compton-camera. Indeed, the emission profile of prompt-gamma photons is spatially correlated to the ion range. The performances of such detection systems can be improved by Time-of-Flight discrimination. A high-count-rate beam hodoscope may be necessary to measure the arrival time of ions on the patient. The MoniDiam project at LPSC is developing an ultra-fast beam tagging hodoscope, based on large area diamond sensors. Diamonds exhibit a fast time response, high resistivity and radiation hardness that make them good candidates for such a detector concept. Polycristalline, single crystal and heteroepitaxially grown on Iridium diamond samples with full planar metallization have been characterized, under different irradiation conditions (α and β particles, 95 MeV/u 12C ions at GANIL, 8.5 keV photons at ESRF and 68 MeV protons at ARRONAX). Characterization results demonstrating time resolution below 100 ps, energy resolution between 7% and 10% and a good charge collection efficiency will be presented. In order to build a 2D position tagging hodoscope, we are also developing double-side stripped diamond sensors. We will present current mapping and time resolution recently obtained with first samples at ESRF (ID21)