High-Resolution 3-D CZT Drift Strip Detectors for Prompt Gamma Ray and Neutron Detection in BNCT

Spectroscopic imagers based on high-Z and wide-bandgap compound semiconductor detectors are widely proposed for the detection of prompt gamma rays in boron neutron capture therapy (BNCT). BNCT is a therapy based on the neutron capture reaction ¹⁰B (n,α)⁷Li. To perform a real-time monitoring of the spatial distribution of ¹⁰B during the treatments, the detection of the prompt gamma rays (478 keV), produced by the ⁷Li recoil nuclei, can be helpful. In this work, we presented the potentialities of new high-resolution CZT drift strip detectors, recently developed by our group, for BNCT measurements. The detectors, exploiting the analysis of the collected-induced charge pulses from anodes, cathodes and drift strips, show excellent energy resolution < 1% at 662 keV at room temperature. The results of preliminary gamma ray measurements under thermal neutrons at the T.R.I.G.A. Mark II research nuclear reactor of Pavia University (Italy) are shown.

I. Introduction

Recently, great efforts have been made in the development of room temperature spectroscopic gamma ray imagers for real-time dosimetry during boron neutron capture therapy (BNCT) [1]. BNCT is a dedicated therapy employed to treat tumour cells using a ¹⁰B compound and thermal neutrons. The high LET of alpha particles produced from the ¹⁰B (n, α)⁷Li reaction is very important in tumour treatment. Real-time monitoring of ¹⁰B is desired during BNCT treatments and several spectroscopic imagers [2], [3] have been proposed to detect the prompt gamma rays of 478 keV emitted during the (n,α) reaction. The main critical issue of these systems is represented by the poor energy resolution, very important to resolve the 478 keV photons from the background produced by neutrons and gamma rays. Recently, new high-resolution CZT drift strip detectors were developed by our group with energy resolution less than 1% at 662 keV [4]. As well known, CZT/CdTe detectors show now appealing properties in room temperature X-ray and gamma ray measurements [5]-[16]. In this work, we will present the potentialities of these detectors for real-time dosimetry in BNCT. The preliminary results from measurements at the T.R.I.G.A. Mark II research nuclear reactor of University of Pavia (Italy) are shown.