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

¹ Dipartimento di Elettronica, Informazione and Bioingegneria, Politecnico di Milano, Milano, 20133, Italy.
² Istituto Nazionale di Fisica Nucleare, Sezione di Milano, Italy.
³ Dipartimento di Energia, Politecnico di Milano, Milano, 20156, Italy.
⁴ Graduate School of Engineering, Nagoya University, Furo-cho, Chikusaku, Nagoya 464-8603, Japan.
⁵ Dipartimento di Fisica, Università di Pavia, Pavia, 27100, Italy.
⁶ Istituto Nazionale di Fisica Nucleare, Sezione di Pavia, Italy.
⁷ Dipartimento di Fisica, Politecnico di Bari, 70126, Bari, Italy.
⁸ Istituto Nazionale di Fisica Nucleare, Sezione di Bari, Italy.

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Published online: 6 November 2025

Abstract

Boron Neutron Capture Therapy (BNCT) is a targeted radiotherapy that requires precise dose monitoring to ensure effective treatment. We initially report experimental measurements performed with the BeNEdiCTE detector, designed for SPECT-based dose monitoring in BNCT. The detector is based on a co-doped LaBr₃(Ce, Sr) monolithic crystal read out by Silicon Photomultipliers and compact electronics. Tomographic measurements were performed at the Laboratorio di Energia Nucleare Applicata in Pavia (Italy). Then, measurements with neutron conditions similar to those expected in clinical treatments were performed at the Nagoya University Acceleratordriven Neutron Source (Japan). The detector demonstrated the ability to detect the 478 keV gamma rays emitted during boron neutron capture reactions. Additionally, the detector successfully reconstructed 2D and 3D images of the boron distribution with sub-centimeter resolution. The measurements highlighted key areas for improvement to make the detector suitable for clinical use with patients, which will be presented in detail in this work. The boron present in the FR4 material used in the electronics boards was identified as a significant source of 478-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 µs to 2.1 µs and refining an energy thresholding mechanism to process only events around 478 keV. These improvements will enhance the detector’s performance, bringing it closer to clinical use with patients.