SLAB-BY-SLAB BLURRING MODEL FOR GEOMETRIC POINT RESPONSE CORRECTION AND ATTENUATION CORRECTION USING ITERATIVE RECONSTRUCTION ALGORITHMS

The distance-dependent geometric point response of a single photon emi ssion computed tomography (SPECT) system and the attenuation effect of photons passing through the object are modeled in an iterative OS-EM reconstruction algorithm to improve both the resolution and quantitati ve accuracy of the reconstructed images. A specified number of neighbo ring vertical slices are grouped into a slab, and an efficient increme ntal slab-by-slab blurring model is introduced to accelerate the recon struction. The advantage of the slab-by-slab blurring model over the s lice-by-slice model is that the computational time is reduced, while s till maintaining the spatial resolution and quantitative accuracy of t he reconstructed images. The application of this incremental slab-by-s lab blurring model with a slice-by-slice attenuation model to the imag e reconstruction of phantom, Monte Carlo simulated SPECT data, and pat ient data shows improved resolution and contrast over the images recon structed without the corrections. The reconstruction is accelerated by a factor of about 1.4, and the projection/backprojection operation is accelerated by a factor of about 5, using the slab-by-slab convolutio n implementation with 8 slices in a slab compared with the slice-by-sl ice convolution implementation.