A Method for Truncation Compensation for Pinhole Tomography

We investigate the effect of multiple circular orbits offset transaxially to improve truncation artifacts. A simulated phantom was placed at a distance from a pinhole collimator that ensured transaxial truncation for the projections. To compensate this truncation, two pinhole scans were then simulated with the axes of rotation (AOR) shifted symmetrically about the central ray. In effect, each scan is used to view half of the object, and the two halves are combined using an OSEM reconstruction. SPECT phantom simulations were performed to compare the dual-orbit approach to a traditional single-orbit acquisition. Further evaluation of the dual-orbit approach with point sources showed that the dual-orbit scan provided higher sensitivity than the single orbit-scan with no loss in resolution. We conclude that the resolution-noise tradeoff for small-field-of-view cameras can be improved with the dual scan procedure.