Performance evaluation of a new gamma imager for small animal SPECT applications

Abstract

Abstract-In this work we characterized a recently developed gamma imager for small animal SPECT applications. The Hamamatsu C9177 is a mini-gamma camera that integrates the detector and all the electronics, including the acquisition system, in a compact and portable housing. The detector is based on a high resolution parallel hole collimator, a CsI(NaI) crystal array and a PS-PMT (flat panel type). The active field of view is 41.9 x 41.9 mm 2 and the assembly is optimized for 60 to 200 keV. The electronics in the housing includes the high voltage divider, an ASIC which converts the 64 anodes into Anger-like signals, ADCs which are fed with these signals and position and energy lookup tables which allow digital information for each detected photon to be obtained directly from the imager. In order to be able to obtain tomographic data and to improve the measurement protocols, we mounted the detector in a custom-built motorized gantry. We evaluated detector uniformity and energy resolution using a flood field image. Planar intrinsic spatial resolution and spatial linearity were assessed by stepping a capillary source across the detector surface and plotting the count profile for each individual crystal of the array. We additionally performed phantom studies to preliminarily characterize the tomographic performance. Energy resolution is 11.6% (mean), sensitivity is 2.54 cps/μCi and planar spatial resolution is 2.4 mm (CFOV 20% energy window) when the source is placed on the detector surface.

Data acquisition electronics for gamma ray emission tomography using width-modulated leading-edge discriminators

“…Over the last 5 years, we have been investigating different approaches for the implementation of combined small-animal PET/CT and SPECT/CT scanners (Vaquero et al 2005, Lage et al 2007, 2009a, 2009b. In this scenario, the aim of this work has been to provide a flexible, high-performance and low-cost hardware platform to test novel detector configurations and to implement the data acquisition system of the emission tomography scanners.…”

Development of an ultra-high resolution SPECT system with a CdTe semiconductor detector

“…To cope with this resolution issue [3], small animal SPECT systems with pinhole collimators have been proposed [4][5][6][7] and lack of the intrinsic spatial resolution of the scintillation detector was compensated for with the geometrical magnification effect of the pinhole collimator. Another strategy to improve the spatial resolution of the small animal SPECT system is utilization of pixelated detectors such as discrete NaI(Tl) or CsI(Tl) crystals [8][9][10][11][12][13] or cadmium telluride (CdTe) or cadmium zinc telluride (CdZnTe) semiconductor detectors [14][15][16][17][18][19][20][21][22][23], which are used with a parallel-hole collimator or pinhole collimator. The pixelated nature of these detectors is expected to greatly improve the spatial resolution when we use very small pixels in a detector at the sacrifice of the detection efficiency.…”