Development and simulation of a SPECT real time dose monitoring system for BNCT: response at the LENA reactor

Boron Neutron Capture Therapy (BNCT) selectively targets tumor cells while sparing healthy ones, by exploiting neutron capture on boron-10, which accumulates to the cancerous cells. To ensure that the therapy is properly tuned, real-time dose monitoring during treatment plays a fundamental role. A Single Photon Emission Computed Tomography (SPECT) imaging system relying on the 478 keV gamma ray emitted by the neutron capture reaction, can, in principle, detect the boron distribution and allow the 3D reconstruction of the dose inside the patient. However, neutron interactions with all the other elements present in tissues and structures introduce background signals, complicating dose evaluation. In this study, FLUKA Monte Carlo simulations were applied to a BNCT-SPECT oriented detector to simulate the image reconstruction process. The simulations were conducted by irradiating the system at the LENA (Laboratorio Energia Nucleare Applicata) in Pavia and compared with experimental data. Moreover, a proof-of-concept study on a SPECT acquisition have been performed on different borated samples. The experimental and simulated results are in good agreement for both image acquisition and detected counting rates. The simulated projections, reconstructed with an appropriated iterative algorithm, show that the presented system is capable of distinguishing two separated vials containing boron-10. This study show that the presented system holds a good promise for enhancing the precision of dose monitoring and localization during clinical BNCT treatments. For this reason, the system will be deployed in real BNCT facilities to evaluate and validate its performance under clinical conditions.