“…A review of some recent developments in small animal SPECT instrumentations was given by Meikle [5]. These developments have benefited from recent advances in gamma ray sensor technologies, which include the high resolution CZT focal plane detector developed at the University of Arizona [6], [7], the multi-pixel Hybrid PhotoDiode (M-HPD) developed at CERN [8], [9], the double-sided silicon strip sensors developed by Peterson et al [10], the silicon drift diode (SDD) array developed by Fiorini et al [11], [12], the Medipix (2) based hybrid pixel sensors developed at CERN [13], [14], EMCCD based mini gamma camera developed by de Vree et al [15], Heemskerk et al [16], Nagarkar et al [17], [18] and Teo et al [19], the GEM based photon sensors coupled to scintillation materials [20], [21], the intensified EMCCD cameras developed by Meng et al [1], [2], the scientific CCD based ultrahigh resolution photon sensors[22], the large area multi-channel plate (MCP) based detectors [23], [24], the avalanche photodiode (APD) detectors reported by Yatsu et al [25] and Shah et al [26], and the solid-state photomultiplier (SSPM) reported by Stapels [27] etc. Some of these developments have pushed the intrinsic detector resolution to well below a hundred micrometers for detecting 27–140 keV gamma rays.…”