BeNEdiCTE (Boron NEutron CapTurE): a Versatile Gamma-Ray Detection Module for Boron Neutron Capture Therapy

We present a gamma-ray detection module for quantifying the boron neutron capture events that occur in Boron Neutron Capture Therapy (BNCT) and Neutron Capture Enhanced Particle Therapy (NCEPT). The goal of the module is to differentiate between the background prompt gamma peaks and the 478 keV neutron capture photopeak, in order to estimate the dose delivered to the patient. It is a compact module, coupling a large array of 64 SiPMs with a 2"×2" cylindrical LaBr3(Ce+Sr) scintillator crystal (73 ph/keV light yield, 25 ns decay time). The electronic front-end ASIC features low-noise processing of photodetector signals, while SiPMs pixellation and individual readout allow for position sensitivity in the crystal, although position estimation is not the object of this work. The module experimental characterization shows excellent energy resolution (2.7% FWHM at 662 keV), that allows to discriminate the neutron capture photons at 478 keV from the annihilation photons at 511 keV. The module features also an anti-coincidence circuit that provides a mechanism to distinguish and reject scintillation events created within specific temporal windows, thus enhancing the signal-to-background ratio of the spectrometer.