Optimal Optical Conditions and Positioning Scheme for an Ultrahigh-Resolution Silicon Drift Detector-Based Gamma Camera

Abstract

In this study, we optimized the optical conditions and associated positioning scheme for an ultrahighspatial-resolution, solid-state gamma detector. The detector module consisted of an array of seven hexagonal silicon drift detectors (SDDs) packed hexagonally and coupled to a single slab of crystal via a light guide glass. Because the optical behavior and requirements of the detector module and noise characteristics of the SDD sensor are different from those of conventional photomultiplier tube (PMT)-based detectors, the following parameters were studied to determine the optimum condition: scintillator selection, the effect of cooling on signal-to-noise ratio (SNR), the depth dependence of the scintillation light distribution, and optimum shaping time. To that end, a modified, Anger-style positioning algorithm with a denoise scheme was also developed to address the estimation bias (pincushion distortion) caused by the excessively confined light distribution and the leakage current induced by the SDD sensor. The results of this study proved that the positioning algorithm, together with the optimized optical configuration of the detector module, improves the positioning accuracy of the prototype detector. Our results confirmed the ability of the prototype to achieve a spatial resolution of about 0.7 mm in full width at half maximum (FWHM) for 122 keV gamma rays under the equivalent noise count (ENC) of 100 (e-rms) per SDD channel. The results also confirmed NaI(Tl) to be a more desirable scintillator for our prototype with an energy resolution performance of about 8%.

Applied Moving-Temperature-Gradient Technique for CsI(Tl) Crystal Growth

“…Also presented in this paper are measurements of temperature gradient drifting characteristics of the furnace, CsI(Tl) crystal growth, and test results of energy resolution. This CsI(Tl) scintillation crystal is slightly hygroscopic and has no cleave plane properties; thus, it is useful in many applications such as radiation safety, 16) radiation imaging, 17,18) and high-energy physics. 19,20) ARTICLE II.…”

A miniature SPECT using multi-pinhole collimator with vertical septa

“…Recently, considerable interest has been grown regarding compact and high resolution gamma cameras [11]. A compact gamma camera based on silicon drift detector (SDD) module has been developed by replacing PMT [12][13][14], and has been studied for SPECT applications. In addition, a flat panel position-sensitive PMT (PSPMT) providing compactness and good packing fraction has been introduced with large imaging FOV using an array of these PSPMTs [15,16].…”

Applied Moving-Temperature-Gradient Technique for CsI(Tl) Crystal Growth

“…Also presented in this paper are measurements of temperature gradient drifting characteristics of the furnace, CsI(Tl) crystal growth, and test results of energy resolution. This CsI(Tl) scintillation crystal is slightly hygroscopic and has no cleave plane properties; thus, it is useful in many applications such as radiation safety, 16) radiation imaging, 17,18) and high-energy physics. 19,20) Ó 2011 Atomic Energy Society of Japan, All Rights Reserved.…”