Abstract: Objective To evaluate the radiation dose levels and image quality of personalized ECG-gated low-dose coronary computed tomography angiography (CCTA) based on iterative reconstruction algorithm (IRA) and body weight index (BMI). Methods One hundred patients with heart rate less than 65 bpm were randomly divided into conventional group (n=50) and low dose group (n=50). In the conventional group, CCTA was performed at regular dose (a voltage of 120 kV and a currency of 800 mAs) and images were reconstructed using filter back projection (FBP). In the low dose group, CCTA was performed at a currency of 280 mAs and a voltage of 80-120 kVp tailored to BMI. The images were reconstructed with FBP and iterative reconstruction algorithm (IRA) at iDOS-5. In both groups, prospective ECG-gated CCTA was employed. CT dose index volume (CTDI), dose-length product (DLP), effective radiation dose (ED), and image quality were compared between conventional group and low dose group. Results Compared with conventional group, CTDI, DLP and ED of the low dose group decreased obviously with statistical significance (P<0.01). The image quality of the low dose group with FBP was 3.72±0.24, which was statistically less than 3.86±0.23 of the conventional group (P<0.01). Using IRA with iDOS-5, the image quality of low dose group increased to 3.81±0.20, which was less than the conventional group with no statistical significance (P>0.05). Conclusion Personalized ECG-gated low-dose CCTA based on IRA and BMI can decrease radiation dose without sacrifice of image quality significantly. It is a cost-effective technique and worth recommending.