Fig. 1

Surface plots for the 37-mm sphere of the NEMA IQ phantom taken from the slice with the largest diameter. The top row refers to BPL reconstructions with increasing penalisation factor (left to right) and the bottom row to PSF reconstructions with increasing width (left to right) of Gaussian post-reconstruction filter. The averaged peak-to-valley ratios from six profiles are also shown on the right for BPL (top) and PSF (bottom) reconstructions for the 37-, 28-, and 22-mm spheres. The error bars represent the standard deviations.