First Compton Telescope Prototype Based on LaBr3-SiPM Detectors
Résumé
A Compton telescope prototype for dose monitoring in hadrontherapy is under development at IFIC Valencia within the European project ENVISION. The detector characterization has been completed and the first imaging tests have been carried out with two detectors operated in time coincidence. The first detector consists of a 16x18x5mm LaBr3 continuous crystal coupled to a SiPM array from Hamamatsu Photonics. The array has 16 elements of 3mmx3mm size, in a 4.05x4.5mm pitch. The second detector is made of a continuous LYSO crystal coupled to a similar SiPM array. The characterization of the LaBr3 detector has shown an energy resolution of 6.5% FWHM at 511 keV. The spatial resolution is better than 1 mm FWHM, and the timing resolution is 2 ns FWHM. Data have been taken with the two detectors in coincidence, with a Na-22 point-like source in different positions, and images have been successfully reconstructed with real data. In addition, a GEANT4 simulation allows us to predict the imaging results with this device both in optimized conditions, and in realistic conditions. Larger detectors consisting of a 32mm x 36mm LaBr3 crystal coupled to four SiPM arrays (of the type previously tested and also monolithic) have been assembled and are being tested. Different readout systems, based on two SPIROC ASICs or on the VATAHDR ASIC are under study for this application.