A Collimator Study Towards BNCT-SPECT Systems for Dose Monitoring

We report the results of a study for the design of a collimator for a BNCT-SPECT system. The goal of the BNCT-SPECT system is to quantify and localize the dose released to a patient during a BNCT treatment, by detecting the 478 keV gamma rays emitted by the 10 B(n,α) 7 Li reactions. However, the extreme high intensity neutron flux of 10 9 n/cm 2 /s and the mixed radiation field present in the irradiation room make this task very challenging. Therefore, the use of an appropriate collimator is required to optimize the Signal/Background ratio and perform tomographic imaging. We propose a detection system based on a 5 cm×5 cm×2 cm LaBr 3 (Ce+Sr) scintillator crystal, coupled to a matrix of 64 Silicon Photomultipliers (SiPMs). ANTS2 simulations have been used to design a pinhole lead collimator, optimizing both the spatial resolution (< 1 cm) and the geometric efficiency (>10 -6 ). A final analytical study have been carried out to confirm the feasibility of our prototype to realize a full ring BNCT-SPECT system.