Development of SiPM-based DEXA detector for large detection area

초록

Silicon photomultipliers (SiPMs) have recently emerged as promising photon-counting sensors for X-ray detectors, owing to their fast response, high gain, and low cost. In this study, we develop an SiPM-based large detection area dual-energy X-ray absorptiometry (DEXA) detector that enables wide fan-beam data acquisition and accurate energy discrimination for low-energy X-rays (<120 keV). The proposed detector system comprises a 128-channel SiPM-based photon-counting detector, a diode-based time-over-threshold circuit, a field-programmable gate array-based time-to-digital converter, and a customized data acquisition system. To assess the performance, we measured the energy spectra and energy resolution using Am-241 and Co-57 point sources. In addition, energy spectra from all 128 channels were acquired using an X-ray generator (83 kVp, 0.3 mA) with a Ce filter that exhibite a K-edge at 40.4 keV. The stability of the low- and high-energy counts was evaluated over a continuous 1-h acquisition period. The wide-area DEXA detector (332 mm × 2.4 mm) achieved energy resolutions of 25.4 ± 1.3 % (60 keV, Am-241) and 21.3 ± 0.8 % (120 keV, Co-57). Two energy peaks in low- and high-energy regions are clearly distinguished in the 128 energy spectra, and the count remains stable within ±1.4 % (low energy) and ±3.2 % (high energy) over 60 min. These results indicate that the proposed wide-area SiPM-based DEXA detector offers sufficient energy discrimination and stability for practical applications in wide fan-beam DEXA imaging.

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