Abstract: Objective: To explore the feasibility of the SEMI mode of the intelligent optimal tube voltage selection technique (Care kV SEMI) in combination with an iterative algorithm in low-dose calcium score scanning for coronary artery examination. Methods: SEMI-automatic tube voltage (Care kV SEMI) and tube current (CareDose 4D on) modulation were used in the phantom experiment. For the SEMI automatic tube voltage group SEMI 120 kV (ref.kV was 100 and 120 kV), ref.mAs was 40, 60, and 80 mAs. The reconstruction algorithms were filtered back projection ADMIRE 3, 4, 5. The volume CT dose index (CTDI_vol), contrast-to-noise ratio (CNR_p) and figure of merit (FOM) of each group were compared, and a set of parameters were selected for clinical patient image acquisition after a comprehensive comparison. A retrospective analysis of coronary artery calcium score scanning images was conducted, using 30 patients as a control group (ref.kV, 120 kV; ref.mAs, 80 mAs; reconstruction algorithm, FBP) and a prospective collection of 109 patients with coronary artery calcium score CT images as an experimental group (Care kV SEMI, 120 kV; ref.kV, 100 kV; ref.mAs, 80 mAs). The reconstruction algorithms were FBP and ADMIRE 3, 5. The dose length product (DLP), effective dose (ED), contrast-to-noise ratio (CNR) at the left main coronary artery (LM) and right coronary artery (RCA) ostial level, Agaston score, and risk classification were recorded and compared between groups. The images of the patients were evaluated by two senior diagnostic doctors on a four-point scale. The radiation dose, calcification score, risk classification, and image quality were statistically analyzed using SPSS software. Results: ① Phantom experiment: The radiation dose of the experimental group was lower than that of the control group. Under the same scanning parameters, the CNR_p increased with an increasing reconstruction algorithm level. The FOM of the four reconstruction algorithms in the ref.kV 100 kV + ref.mAs 80 mAs group was higher than that in the control group. ② Clinical study: There was a statistically significant difference in ED between the experimental group and the control group (P < 0.001). There was no statistically significant difference in CNR_c between the experimental group with FBP and the control group on the LM and RCA levels (P > 0.0125).There was no significant difference in Agaston score between the experimental and control groups (P > 0.05). The consistency of the risk grade in the experimental group was good, with kappa values of 0.93 and 0.88, respectively. There was no statistically significant difference in FBP and CNR_c between the experimental and control groups at either level (P > 0.0125). The subjective evaluation results of doctors A and B were consistent, and the kappa value was 0.952. There was a statistically significant difference in the subjective evaluation between the two groups (P < 0.001). Conclusion: Care kV SEMI combined with an iterative algorithm has little effect on the calcification score and risk classification, and it can effectively reduce the radiation doses of patients with a BMI of 18–25.