講演情報
[8p-E204-8]Double-Photon Coincidence Imaging Using Double-Sided Shifted MPPC Readout
〇Moh Hamdan1,2, Boyu Feng1, Amin Choghadi1, Shuwei Zhao1, Sotaro Miyao1, Yuki Mitsuya1, Setsuo Sato1, Kenji Shimazoe1, Nobuyoshi Akimitsu1, Hiroyuki Takahashi1,2 (1.The University of Tokyo, 2.Fukushima Institute for Research, Education and Innovation)
キーワード：
Scintillation Detector、Double-Sided Shifted MPPC、Double Photon Coincidence Imaging
Double-photon coincidence imaging has been widely studied for imaging cascade-emitting radionuclides such as 111In. By combining a parallel-hole collimator with coincidence photon-pair detection, radionuclide distributions can be reconstructed with reduced background compared with conventional single-photon imaging. However, the spatial resolution is limited by the detector pixel pitch. To improve the resolution, a detector employing a 1.1-mm-pitch scintillator array and a double-sided shifted MPPC readout configuration was developed. The shifted configuration enables unique identification of individual crystal pixels from paired MPPC signals. The detector consisted of a 16 × 16 YAGG scintillator array (pitch: 1.1 mm, crystal size: 0.9 × 0.9 × 4.0 mm3) separated by BaSO4 reflectors and coupled to double-sided 8 × 8 MPPC arrays (pitch: 2.2 mm, pixel size: 2 × 2 mm2). The imaging system comprised four detector modules. For three-dimensional position determination, two detectors employed tungsten parallel-hole collimators (pitch: 1.1 mm, hole diameter: 0.6 mm, thickness: 15 mm) to determine X–Z coordinates, while the other two used lead parallel-slit collimators (pitch: 1.1 mm, slit width: 0.7 mm, thickness: 15 mm) to determine the Y coordinate. Two microtubes containing 111In (~0.41 MBq, 15 µL each) with a center-to-center spacing of approximately 5.5 mm were used to evaluate imaging performance. The reconstructed image successfully resolved the two sources. The measured FWHM ranged from 2.16 to 2.56 mm, primarily limited by the source size, and a figure of merit of 0.84 was achieved. The system performance was evaluated using time-difference distributions, energy spectra, sensitivity, and signal-to-background ratio measurements. These results demonstrate the feasibility of high-resolution double-photon coincidence imaging using the proposed readout configuration.