Speedup OS-EM image reconstruction by PC graphics card technologies for quantitative SPECT with varying focal-length fan-beam collimation

In this paper, we present a new hardware acceleration method to speedup the ordered-subsets expectation-maximization (OS-EM) algorithm for quantitative single photon emission computed tomography (SPECT) image reconstruction with varying focal-length fan-beam (VFF) collimation. By utilizing the geometrical symmetry of VFF point-spread function (PSF), compensation for object-specific attenuation and system-specific PSF are accelerated using currently available PC video/graphics card technologies. A tenfold acceleration of quantitative SPECT reconstruction is achieved.