Experimental validation of a spectroscopic gamma-ray detector based on a LaBr3 scintillator towards real-time dose monitoring in BNCT

We report the experimental validation of a detection module based on a LaBr3(Ce+Sr) scintillator crystal, read by a matrix of Silicon Photomultipliers (SiPMs), for the development of a SPECT system for dose monitoring in Boron Neutron Capture Therapy (BNCT). The goal of the system is to detect the gamma rays at 478 keV emitted by the excited Li-7 produced in the B-10(n, alpha)Li-7 reaction, to have a real-time localization and quantification of the local dose released to a patient during BNCT treatment. The good energy resolution of the detector (< 3% at 662 keV) allows to resolve the photopeak at 478 keV from the adjacent annihilation photons photopeak at 511 keV, originated from pair production of high energy gamma rays, such as the hydrogen neutron capture gamma rays at 2.2 MeV. The results shown in this article demonstrate the suitability of our detector in view of future application in BNCT real-time dose monitoring. Good linearity (RMSE < 2.5 cps) between the number of events detected at 478 keV and the boron concentration of the B-10-loaded samples has been achieved, down to a boron concentration of 62 ppm with a neutron flux of approximately 1 x 10(5) n/cm(2)/s.