optimization of retrospective gated-ecg coronary computed tomography angiography by dose reduction in patients with different body mass indexes

Background: the reduction of patient radiation dose in coronary computed tomography angiography (ccta) with acceptable image quality is considered an important factor in the research.objective: this study aims to optimize the ccta protocol using a retrospective electrocardiogram (ecg)-gated axial scan protocol in patients with different body mass indexes (bmis).material and methods: in this cross-sectional study, 66 patients into three main groups: 80 kvp (group a), 100 kvp (group b), and 120 kvp (group c), underwent ccta. each group was then divided into two subgroups of bmi<25 and >25 kg/m2. image noise, mean vascular attenuation at the aorta, signal-to-noise ratio (snr), and contrast-to-noise ratio (cnr) at five regions of coronary arteries, in which coronary artery anomalies are common were qualitatively evaluated by subjective image quality analysis.results: at each kvp, there were no significant differences in cnr, snr, noise level, and the effective dose between bmi>25 kg/m² and bmi<25 kg/m². the effective radiation dose of groups a, b, and c were 4.16, 8.46, and 14.3 msv, respectively. subjective image quality assessment scores were 3.18, 3.5, and 3.73 out of 4 in groups a, b, and c, respectively. conclusion: patient radiation dose using retrospective ecg-gated ccta can be reduced by about 70% at 80 kvp, which is almost close to the prospective ccta dose ranges. the retrospective ccta at 80 kvp can be optimized even in overweight patients (bmi>25 kg/m2).