Performance measurement of the scintillator with optical fiber detector for boron neutron capture therapy

Komeda, Masao   ; Kumada, Hiroaki; Ishikawa, Masayori*; Nakamura, Takemi  ; Yamamoto, Kazuyoshi ; Matsumura, Akira*

The thermal neutron flux can be easily measured in real time by using the SOF (Scintillator with Optical Fiber) detector. However the irradiation damage under high-intensity neutron flux causes the deterioration of the SOF detector due to the plastic scintillator in which LiF is blended. After irradiating the SOF detector for 4 hours (thermal neutron fluence approximately 2.010 neutrons/cm), the sensitivity of the SOF detector decreased by 3.0%. After irradiating the SOF detector for 2 months (thermal neutron fluence approximately 6.410 neutrons/cm), the sensitivity was reduced to 42%. Supposing that the thermal neutron fluence is 210 (neutrons/cm) on the surface of a patient in a BNCT treatment, the sensitivity of the SOF detector is reduced by approximately 0.3%. This report presents investigations on the deterioration of the SOF detector in irradiation experiments.