A novel phantom for evaluating contrast resolution in SPECT

Objectives We have designed a phantom to evaluate acquisition and reconstruction parameter using contrast transfer function (CTF). This phantom was consisted of differently-spaced (0 - 14 mm, 1mm intervals) pair of cubic containers (5 mm width, 20 mm length and 50mm height). The goal of this study was to evaluate accuracy of this phantom for contrast resolution.

Methods Our approach includes two major components; (1) comparison real value measured count profile using this phantom with theoretical value obtained by line spread function (LSF) using line source; (2) correlation the distance between pair of cubic containers and CTF. A SPECT acquisition was 256 x 256 matrix (pixel size: 0.9 x 0.9 mm2), 360 degree at 30 sec/view. Reconstructions were performed with filtered backprojection and ordered subsets expectation maximization method (10 iterations, 10 subsets) with or without collimator-detector response correction.

Results The actual measured count profile accorded closely with theoretical one. CTF rose in direct proportional to container spacing.

Conclusions This phantom may be useful method for evaluating acquisition and reconstruction parameter in SPECT