Table 1.

The mean and standard deviation of FD values (D _B) for different DR grades.

DR grade	Number of images	ROI: full FOV			ROI: 5 × ODr
		Mean	SD∗	RSD†	Mean	SD	RSD
R0	546	1.3864	0.0324	2.34%	1.3285	0.0316	2.38%
R1	153	1.3852	0.0345	2.49%	1.3317	0.0304	2.28%
R2	247	1.3781	0.0364	2.64%	1.3215	0.0384	2.91%
R3	254	1.3869	0.0384	2.77%	1.3276	0.0375	2.82%
Total	1200	1.3846	0.0350	2.52%	1.3273	0.0343	2.59%

^∗SD: standard deviation.

^†RSD: relative standard deviation.