Table 4.

Evaluation of contrast-noise-ratio (CNR) with Catphan sensitometry module*

	Dose level	30 MU	60 MU
	Insert #1	3.7	6.4
	Insert #2	1.2	2.2
	Insert #3	0.2	0.4
	Insert #4	0.2	0.5
	Insert #5	0.3	0.6
	Insert #6	0.7	1.1
	Insert #7	1.2	2.2
	Insert #8	1.0	1.8

^*For CNR measurement at each insert, the in-plane ROIs were placed at the center of each insert and the immediate background region. ROI diameter—0.8 cm; slice thickness—0.3 cm. The inset illustrates the indices of inserts