Design and Simulations of a Collimator for SPECT Measurements in a BNCT Facility

This study presents the development of a new collimator design for a BNCT-SPECT system, tailored to overcome limitations that could be encountered in a BNCT clinical facility. BNCT-SPECT systems aim to quantify and localize the dose administered to a patient during Boron Neutron Capture Therapy (BNCT) by detecting the 478 keV gamma rays emitted from ${ }^{10} \mathrm{~B}(\mathrm{n}, \alpha)^{7}$ Li reactions. The presence of boron also inside the irradiation room walls in most of the clinical BNCT facilities, brought us to reconsider a collimator already designed ad hoc to fullfill all the requirements of this treatment. Helped by FLUKA simulations, we define the main drawbacks of our current system in a clinical scenario, and propose a new configuration to overcome this limitations. We report the specifics of the new design, highlighting the capability to distinguish a boron source from the background radiation over 10 ppm concentration.