Research of Photon Counting Dual-energy X-ray Absorptiometry Based on SiPM

Recently there has been an increase of clinical cases of osteoporosis due to an increase in the ageing population. As an established diagnostic tool for osteoporosis, dual-energy x-ray absorptiometry (DEXA) is widely used due to its high accuracy, precision and image quality. In recent years, a new type of silicon-based photomultipliers, SiPMs, has been developed which has high potential to be used in photon counting DEXA detectors for its compact size and reliable performance. In this work, we designed a DEXA test platform with a SiPM and evaluated its performance using various bone density imaging parameters. The experimental DEXA platform is constructed with a fan-beam geometry consisting of an x-ray source from Spellman and a self-developed scanning motion control system. We studied the performance characteristics of a 64-channel YSO/SiPM array detector and compared them with a cadmium zinc telluride (CZT) detector. The maximum-likelihood (ML) estimation method was used to optimize the surface fitting algorithm to achieve high material decomposition accuracy. The results show the average error of the YSO/SiPM detector is 1.24% for PMMA and 1.72% for Al. We conclude the YSO/SiPM detector can achieve material decomposition accuracy close to CZT detector and it has the potential in DEXA imaging with good imaging performance characteristics at low cost.