Fig. 4

HRRT RCs (%) as a function of voxel noise (%) for two different sphere sizes and for a high and low count frame for the contrast phantom (19.8 mm sphere: high count frame (a), low count frame (b); 9.9 mm sphere: high count frame (c), low count frame (d)). The high count frame corresponds to ~ 135 million prompts within the frame, the low count frame to ~ 12 million prompts. Note the difference in x-axis limits. HRRT data were reconstructed without any filters (native), with a 2-mm Gaussian filter (standard in-house reconstruction for human data), with PSF, and with PSF correction and 2-mm filter using 16 subsets, respectively. High count data were analyzed based on a single realization while low count data were based on five replicates. Each point represents an OSEM iteration, and the number of iterations increases from left to right. The dotted line represents the PET/MR reconstruction (wTOF, PSF, 3.5-mm Gaussian filter) used for human data reconstruction