Table III.

Quantitative assessment of differences between reconstructions with and without non-negativity for the head phantom with sparse and full view sampling. The minimum and maximum voxel differences are given, as well as the mean and standard deviation in the root mean square difference over the last 500 iterations. All values are in HU and measured inside the ROI. The last column reports the statistical variability of $\overline{\text{RMSD}}$ over scan repetitions.

	Min.	Max.	$\overline{\text{RMSD}}$	SV
Head phantom
Full view sampling	−2.8	2.6	0.1887 ± 0.0000	0.0044
Sparse view sampling	−48.0	36.1	2.1428 ± 0.0004	0.0289