Fig. 3

Spheres in ¹¹C-silicone scanned on GE Discovery 690 PET/CT. Two image series, both with PSF, based on the same PET raw data were analyzed. a VuePoint FX SharpIR with TOF and PSF (3 iterations, 24 subsets 4-mm 2D Gaussian filter, and [1, 1, 6] axial convolution filter, 192 × 192 matrix, voxel size 3.7 × 3.7 × 3.3 mm³) with moderate spatial resolution; and b VuePoint FX SharpIR with TOF and PSF (4 iterations, no post-filter, 256 × 256 matrix, voxel size 2.0 × 2.0 × 3.3 mm³) with higher spatial resolution. VOI definition, symbols, and axes are as described in Fig. 2. Similar to Fig. 2b, this PSF algorithm also leads to images where RCs can be non-monotonic function of sphere size with RC_50bg > 1, and with the highest RCs for 8–10 mm spheres