Reconstruction CPU times for the Advance scanner, plotted as a function of the number of oblique segments, for 4 iterations OSEM with 14 subsets and four reconstruction schemes. Each sinogram of the raw projection data had 283 unevenly-spaced LORs and 336 angles, and the reconstruction matrix was 128 × 128 × 35 slices. The first three curves are for fully-3-D LOR-OSEM, and the final curve is for Fourier rebinning followed by 2-D AW-OSEM. Using the rotate-and-slant projector with depth-compression factor of 8, total processing time for fully-3-D iterative reconstruction was similar to that for 2-D reconstruction.