Development of a prompt gamma-ray detector with an 8 × 8 array LaBr 3(Ce) scintillator and a multi-pixel photon counter for boron neutron capture therapy

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2023-10, Vol.1055, p.168546, Article 168546
• Main Authors: Okazaki, Keita, Tanaka, Hiroki, Takata, Takushi, Kawabata, Shinji, Hu, Naonori, Matsubayashi, Nishiki, Mukawa, Tetsuya, Sakurai, Yoshinori, Suzuki, Minoru
• Format: Article
• Language: English
• Subjects: Boron neutron capture therapy; Multi-pixel photon counter; Pixelated-array scintillator; Prompt gamma-ray analysis; Real-time detection
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2023.168546

A prompt gamma-ray detector for measuring the boron-10 concentration in real time for boron neutron capture therapy was researched. Our previous detector, which comprised a scintillator made from a slab of LaBr3(Ce) and an 8 × 8 array multi-pixel photon counter (MPPC), discriminated between 478 keV and 511 keV gamma rays. However, the spatial resolutions of the detector were not applicable to the detection of the boron concentration distribution. An 8 × 8 pixelated LaBr 3(Ce) scintillator has been employed to improve the spatial resolution. In our previous report, the spatial resolution was improved by using the pixelated scintillator. However, the scintillation light produced in one pixel was sufficient to saturate the photon counts above 229 keV. Thus, a single peak was separated when the signals of all 64 channels were summed up. Many photon counts were eliminated to obtain the observed gamma-ray spectrum. In this study, an advanced 8 × 8 MPPC was employed, and the detector system had an energy resolution of 6.15% at 511 keV and spatial resolutions of 2.88 and 2.95 mm in the lateral and vertical directions, respectively, without eliminating any photon counts. In addition, the linearity of the photon counts of the 478 keV gamma rays and boron concentration was confirmed. •A prompt gamma-ray imaging detector was developed with an arrayed LaBr3(Ce) scintillator and a multi-pixel photon counter.•The energy resolution at 511 keV was 6.15% which was sufficient to discriminate between 478 and 511 keV gamma rays.•This detector system had the linearity between ADC channels and gamma-ray energies.•The linearity between B-10 concentration and the count rate of prompt gamma rays at 478 keV was confirmed.•The spatial resolution of this detector system was better than our previous detector system.