Table 4. Statistical Analysis of Image Quality Scores of Different Algorithms (Mean ± SD).

		Normal-dose	Low-dose	ASD-POCS	KSVD	BM3D	CNN200
Artifact reduction	R1	3.95 ± 0.60	1.95 ± 0.69*	2.85 ± 0.59*	2.60 ± 0.50*	3.45 ± 0.60*	3.65 ± 0.58
	R2	4.05 ± 0.51	1.95 ± 0.51*	2.95 ± 0.39*	2.90 ± 0.39*	3.40 ± 0.60*	3.80 ± 0.52
	R3	3.95 ± 0.22	1.75 ± 0.44*	2.80 ± 0.41*	2.75 ± 0.44*	3.40 ± 0.50*	3.80 ± 0.41
	Average	3.98 ± 0.47	1.88 ± 0.56*	2.87 ± 0.47*	2.80 ± 0.48*	3.42 ± 0.56*	3.75 ± 0.51
Noise suppression	R1	3.90 ± 0.64	1.70 ± 0.57*	3.05 ± 0.51*	3.00 ± 0.46*	3.60 ± 0.50	3.65 ± 0.49
	R2	4.25 ± 0.44	1.85 ± 0.49*	3.50 ± 0.51*	3.40 ± 0.50*	4.05 ± 0.39	4.05 ± 0.51
	R3	3.90 ± 0.31	1.55 ± 0.51*	3.00 ± 0.56*	3.05 ± 0.60*	3.65 ± 0.49	3.75 ± 0.55
	Average	4.01 ± 0.50	1.70 ± 0.53*	3.18 ± 0.57*	3.15 ± 0.55*	3.77 ± 0.50*	3.82 ± 0.54
Contrast retention	R1	3.85 ± 0.59	1.65 ± 0.49*	2.65 ± 0.49*	2.80 ± 0.52*	3.50 ± 0.51*	3.55 ± 0.51*
	R2	3.95 ± 0.39	1.55 ± 0.51*	2.60 ± 0.50*	2.85 ± 0.49*	3.50 ± 0.51*	3.55 ± 0.51*
	R3	3.95 ± 0.39	1.85 ± 0.49*	2.60 ± 0.50*	2.95 ± 0.22*	3.55 ± 0.51*	3.50 ± 0.51*
	Average	3.92 ± 0.46	1.68 ± 0.50*	2.62 ± 0.49*	2.87 ± 0.43*	3.52 ± 0.50*	3.53 ± 0.50*
Overall image quality	R1	3.85 ± 0.49	1.75 ± 0.44*	2.65 ± 0.49*	2.70 ± 0.47*	3.55 ± 0.51	3.65 ± 0.49
	R2	3.90 ± 0.31	1.65 ± 0.49*	2.95 ± 0.22*	3.05 ± 0.22*	3.60 ± 0.60*	3.70 ± 0.57
	R3	3.85 ± 0.37	1.55 ± 0.51*	2.70 ± 0.47*	2.75 ± 0.44*	3.60 ± 0.50	3.65 ± 0.49
	Average	3.87 ± 0.39	1.65 ± 0.48*	2.7 ± 0.43*	2.83 ± 0.42*	3.58 ± 0.53*	3.67 ± 0.51

* indicates $P<0.05$, which means significantly different.