Fig. 1.

Example dataset showing the effect of increasing iterations. The first two panels show the background SUVmean (a) and the SUVstd (b), as a function of the number of iterations, for TOF OSEM with 28 subsets and for TOF BSREM with regularization parameter β = 350, 400, 450, 500, and 700. The remaining 4 panels show the lesion SUVmax as a function of the number of iterations for 5 lesions (L1–L5) for TOF OSEM with 28 subsets (c) and for TOF BSREM with regularization parameter β = 350 (d), 400 (e), and 700 (f). The arrows indicate the default reference TOF OSEM reconstruction with 28 subsets and 2 iterations. SUV standardized uptake value, SUVmean the average value of the voxels in the background ROI, SUVstd the standard deviation of the values of the voxels in the background ROI, SUVmax the average of the hottest 5 voxels in the lesion, TOF time-of-flight, OSEM ordered subset expectation maximization, BSREM block sequential regularized expectation maximization