Table 3.

Evaluation of image uniformity with Catphan uniformity module: mean CT number ± standard error at each region-of-interest (ROI) *

Dose level	30 MU	60 MU
Central ROI	1.7 ± 2.0 HU	0.6 ± 1.2 HU
Peripheral ROI #1	1.5 ± 1.6 HU	− 1.0 ± 0.9 HU
Peripheral ROI #2	1.3 ± 1.6 HU	− 0.2 ± 0.9 HU
Peripheral ROI #3	− 0.4 ± 1.5 HU	− 0.4 ± 1.0 HU
Peripheral ROI #4	− 1.4 ± 1.6 HU	− 1.1 ± 1.0 HU

^*In-plane ROI diameter—2.3 cm; slice thickness—0.3 cm