A feasibility study of LYSO-GAPD detector for DEXA applications

Abstract

A LYSO-GAPD detector module was developed for use in DEXA applications, and it was characterized under a variety of conditions. The LYSO with 3 mm × 3 mm × 2 mm pixel size provided a detection efficiency of > 99.9% at 80 keV . It was coupled to a GAPD with an active area of 3.07 mm × 3.07 mm and 5676 microcells. The energy spectra were acquired using different gamma rays. The X-ray energy spectra were measured as a function of different tube voltages and currents. A pulse pileup effect was observed under extremely high incident photon conditions at a tube current > 0.5 mA. The maximum count rate was 2 Mcps, mainly due to the dead time of the data acquisition unit. Dual energy peaks were clearly isolated, and the peak-to-valley ratio as a function of K-edge filter thickness increased from 2.8 to 14.2 and from 1.7 to 3.8 for the low- and high- energy-band, respectively. The DEXA phantom image for each step was clearly resolved. These results demonstrate the feasibility of using the LYSO-GAPD detector to develop a DEXA scanner.