Development of a thick CdTe detector for BNCT–SPECT

As well known, it is difficult to know the exact treatment effect of boron neutron capture therapy (BNCT). It depends on the irradiation time, which is changed rather flexibly. At present, it is once fixed before BNCT. Then the actual stopping time is adjusted during BNCT by some means like activation foils. The author's group hence started development of a single-photon emission computed tomography (SPECT) system for BNCT to know the effect of BNCT in real time. By adopting a side surface (1×2 mm2) of a CdTe detector (1×2×20 mm3) as radiation entrance window, acceptable spatial resolution and high detection efficiency were simultaneously achieved. Also in about 30 min acceptable number of counts for 478 keV gamma-rays could be expected. In addition, employing a Schottky type detector the energy resolution could be improved. Discrimination of 478 keV and annihilation gamma-rays would thus be successfully made. In the next phase, it is planned to design and develop an array type detector to be implemented in the BNCT–SPECT system.

► BNCT needs treatment effect information, but very difficult to measure.
► CdTe device is employed to develop BNCT–SPECT to know 3-D BNCT effect.
► Using side surface of CdTe wafer as radiation entrance SPECT performance is enhanced.
► In 30 min enough count around 1000 can be obtained for 478 keV gamma-rays.
► Array type CdTe detector is now designed for prototype BNCT–SPECT.