A fast projector-backprojector pair modeling the asymmetric, spatially varying scatter response function for scatter compensation in SPECT imaging

Slab derived scatter estimation (SDSE) accurately models the asymmetric, spatially varying scatter response function in uniformly attenuating objects with convex surfaces. This model is implemented in a projector-backprojector that, when combined with iterative reconstruction techniques, provides accurate scatter compensation in single-photon emission computed tomography (SPECT). These iterative reconstruction-based scatter compensation techniques have the advantage that they use all detected photons, avoiding the noise amplification occurring with subtraction based schemes. Scatter compensation with iterative reconstruction does not involve the use of arbitrary adjustable parameters. A new fast algorithm for implementing SDSE that reduces computation time by a factor of 16 compared to a direct implementation is presented. Projection data computed with the new algorithm compare well with data from Monte Carlo simulations