Experimental comparison of three reconstruction algorithms for single-orbit cone beam SPECT

This study compared single-orbit cone-beam SPECT reconstructed image quality obtained from the Feldkamp algorithm, the Grangeat algorithm and the nonstationary filtering (NSF) algorithm which the authors previously developed. Acquired data from two physical phantoms, a 3D Defrise slab phantom and a 3D Hoffman brain phantom, were processed using the 3 algorithms and the results were compared in terms of image artifacts, noise, and processing time. From the slab phantom data, the 3 algorithms produced similar artifacts which were related to single-orbit cone-beam geometry. From brain phantom data, the Grangeat algorithm produced additional artifacts and distortions, while the NSF algorithm slightly reduced the cone-beam related artifacts compared to the Feldkamp algorithm. The processing time required by the Grangeat and NSF algorithms were respectively 2 and 4 times of that needed by the Feldkamp algorithm. Currently, the Feldkamp algorithm appears the best choice in terms of both image quality and processing time for single-orbit cone-beam SPECT with a cone angle less than 15°