Fig. 9

Contrast plotted against sphere diameter for all the image protocols for the different reconstructions with a 12-mm Gaussian filter. Contrast was calculated with Eq. 4, except for when the source VOI included no counts. In cases with no counts in the source VOI, contrast was set to 0 to find averages and SDs. The equivalent plots based on unfiltered images can be found in the supplementary material. The ME 239 keV results are shown in panel a, the ME 79 keV results are shown in panel b, the HE 239 keV results are shown in panel c, and the HE 79 keV results are shown in panel d