Table 3.

SSIM and PSNR values in each dispersed projection angle with artifact reduction by deep learning models. These values were calculated based on the original CT image. *p-values of < 0.005 were deemed significant for differences from the results of corresponding results of artifacts image.

	Interval of projection data acquisition angle
	1°	2°	5°	10°
SSIM
With artifacts	0.87 ± 0.02	0.58 ± 0.02	0.29 ± 0.02	0.17 ± 0.02
AE	0.40 ± 0.03*	0.38 ± 0.02*	0.37 ± 0.02*	0.31 ± 0.03*
U-Net	0.41 ± 0.03*	0.41 ± 0.03*	0.40 ± 0.03*	0.31 ± 0.02*
CGAN	0.94 ± 0.02*	0.90 ± 0.03*	0.87 ± 0.02*	0.79 ± 0.02*
PSNR
With artifacts	33.6 ± 0.3	26.8 ± 0.3	19.7 ± 0.4	16.0 ± 0.5
AE	24.8 ± 0.1*	24.5 ± 0.1*	23.3 ± 0.2*	20.4 ± 0.4*
U-Net	24.9 ± 0.1*	24.8 ± 0.1*	24.0 ± 0.1*	21.1 ± 0.3*
CGAN	36.7 ± 0.7*	33.3 ± 0.4*	29.3 ± 0.4*	23.7 ± 0.6*

*p < 0.005, showing a significant difference from the artifact conditions.