Table 1.

Hyperparameter selection study for (a) TV and (b) proposed methods. STD denotes the standard deviation. The bias and standard deviation using the regular dose FBP image as ground truth and the processed quarter dose image were computed by various β, α and σ. Here, α is the soft‐thresholding value as used in the literature.¹⁶ The bold hyperparameters in (i) and (ii) were used for image quality comparison throughout our experiments, as shown in Fig. 4. Unit of bias and standard deviation is 10⁻⁴ mm⁻¹

(a)	β	α	Bias	STD
(i)	0.02	0.0017	3.55	6.32
	0.02	0.002	3.55	6.13
	0.03	0.0014	3.58	5.91

(b)	β	σ	Bias	STD
(ii)	0.01	0.037	3.47	6.22
	0.02	0.037	3.52	6.12
	0.03	0.031	3.55	6.10
	0.04	0.031	3.57	6.00