Objective: This study sought to compare the radiation dose and image quality between a snapshot assist (SSA) scanner and a conventional scanner in retrospective electrocardiographically (ECG)-gated coronary computed tomographic (CT) angiography to assess the clinical value of the SSA scanner in reducing radiation dose. Methods: Ninety-five patients with known or suspected coronary artery disease (CAD) undergoing retrospective ECG-gated Coronary CT Angiography were enrolled and divided into

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... A (n=47, with SSA scanner) and group B (n=48, with conventional scanner). The image quality scores, mean CT attenuation values in the ascending aorta, image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were assessed, and the radiation dose was compared between groups A and B. Results: There were no significant differences in patient sex, age, and mean body mass index (BMI) between the two groups. There were no significant differences in image quality scores for total segments between the two groups (χ2=0.147, P>0.05). The mean CT attenuation values in the ascending aorta were not significantly different between the two groups (t=1.120, P>0.05). There were no significant differences in SNR and CNR between the two groups (P>0.05). The effective dose (ED) of group A was 41.65% lower than group B (6.29±1.68 vs. 10.78±1.58mSv). Conclusion: SSA technology provides equivalent or better coronary image quality with retrospective ECG gated coronary angiography than the conventional scanner while enabling radiation dose reductions of 41.65%.