Objective: To characterize the optimal pre-(ASiR-V and post-ASiR-V for improving image quality and reducing the radiation dose in CCTA. Methods: The study was divided into two parts. In part I, 150 patients for CCTA were prospectively enrolled and randomly divided into five groups (A, B, C, D, and E), with progressive scanning from 40% to 80% pre-ASiR-V with 10% intervals and reconstructing with 70% post-ASiR-V. The SNR and CNR were calculated. Subjective image quality was assessed using a five-point scale. The radiation dose was recorded and calculated after statistical analysis by optimizing for the best pre-ASiR-V value with the lowest radiation dose while maintaining overall image quality. In part II, the images were reconstructed with the recommended optimal pre-ASiR-V values in part I (D group) was divided into six subgroups (D0-D5 with 40%-90% post-ASiR-V and interval 10%, respectively.).The SNR and CNR of D0-D5 subgroups were calculated and analyzed using one-way analysis of variance, and the consistency of the subjective scores used the k test. Results: There was no significant difference in the SNRs, CNRs, and image quality scores among A, B, C, and D groups. The SNR, CNR, and image quality scores of the E group were lower than those of the A, B, C, and D groups. The mean EDs in the B, C, and D groups were reduced by 7.01%, 13.37%, and 18.87%, respectively, when compared with that of the A group. The SNR and CNR of the D4–D5 subgroups were higher than the D0-D3 subgroups, and the image quality scores of the D4 subgroups were higher than the other subgroups. Conclusion: The wide-detector combined with 70% pre-ASiR-V and 80% post-ASiR-V significantly reduced the radiation dose of CCTA while maintaining overall image quality compared with the manufacture’s recommendation.