Fig. 9

Number of OSEM updates and Gaussian filtering analysis example using the 6-mm 2-to-1 ratio pituitary tumor phantom. The 6-mm pituitary tumor phantom with a 2-to-1 ratio of activity concentration was reconstructed using 1-, 2- and 3-mm post-reconstruction Gaussian filters and 3, 5, 7 and 9 numbers of OSEM iterations all with 24 subsets. The central slice of the resulting 12 images is displayed in panels (A–C, E–G, I–K and M–O). The signal along with the horizontal part of the cross-hairs is shown as profiles in panels (D, H, L and P)