Towards Clinical Integration of a SPECT Detection Module for BNCT Dose Monitoring

Boron Neutron Capture Therapy (BNCT) is a targeted radiotherapy that requires precise dose monitoring to ensure effective treatment. We present experimental measurements performed with the BeNEdiCTE detector, designed for SPECT-based dose monitoring in BNCT. The measurements were conducted in Japan, at the Nagoya University Accelerator-driven Neutron Source facility. This facility provides neutron conditions similar to those expected in clinical treatments. The detector is based on a co-doped $\text{LaBr} 3(\text{Ce}, \text{Sr})$ monolithic crystal read out by Silicon Photomultipliers and compact electronics. It demonstrated the capability to detect the 478 keV gamma rays emitted during boron neutron capture reactions. Additionally, the detector successfully reconstructed images of the boron distribution with sub-centimeter resolution. The measurements also highlighted key areas for improvement to make the detector suitable for clinical use with patients. The boron present in the FR4 material used in the electronics boards was identified as a significant source of $478-\text{keV}$ gamma rays uncorrelated with the imaged object. To mitigate this, a new substrate material, RO3003, was tested, showing a substantial reduction in gamma rays emitted at 478 keV. Furthermore, the detector's electronics were optimized to improve count-rate capability. This involved reducing the dead time from $5.4 \mu ~\mathrm{s}$ to $2.1 \mu ~\mathrm{s}$ and refining an energy thresholding mechanism to process only events around 478 keV. These improvements, as well as others presented at the conference, will enhance the detector's performance, bringing it closer to clinical use with patients.