A CONE-BEAM FILTERED BACKPROJECTION RECONSTRUCTION ALGORITHM FOR CARDIAC SINGLE PHOTON-EMISSION COMPUTED-TOMOGRAPHY

A filtered backprojection reconstruction algorithm was developed for cardiac single photon emission computed tomography with cone-beam geometry. The algorithm reconstructs cone-beam projections collected from "short scan" acquisitions of a detector traversing a noncircular planar orbit. Since the algorithm does not correct for photon attenuation, the algorithm is designed to reconstruct data collected over an angular range of slightly more than 180-degrees with the assumption that the range of angles is oriented so as not to acquire the highly attenuated posterior projections of emissions from cardiac radiopharmaceuticals. This sampling scheme is performed to minimize the attenuation artifacts that result from reconstructing posterior projections. From computer simulations, we find that reconstruction of attenuated projections has a greater effect upon quantitation and image quality than any potential cone-beam reconstruction artifacts resulting from insufficient sampling of cone-beam projections. With nonattenuated projection data, cone-beam reconstruction errors in the heart are shown to be small (errors of at most 2%) which is the result of the heart being positioned near the central plane of the cone-beam geometry. Artifacts increase in the surrounding tissue at distances further from the central plane.