Table 4:

Statistical differences (P values) between the regular- and lower-dose CT groups

Radiation Dose	Reconstruction Technique	Quantitative Measurements (P values)
Radiation Dose	Reconstruction Technique	GM-SNR	WM-SNR	GM-WM CNR
Regular (175 mAs)	100% FBP		Control group
	100% FBP	.003^a	.003^a	.4
	20% ASIR + 80% FBP	.649	.541	1
Lower-Dose (140 mAs)	40% ASIR + 60% FBP	.302	.668	.03^a
	60% ASIR + 40% FBP	<.0001^a	<.0001^a	<.0001^a
	80% ASIR + 20% FBP	<.0001^a	<.0001^a	<.0001^a
	100% ASIR	<.0001^a	<.0001^a	<.0001^a

↵a Statistical significance between the lower-dose (with different ASIR/FBP levels) and regular-dose groups.