Objective: To evaluate the effect of noise-based low tube current scanning combined with low kilovoltage on image quality and radiation dose in coronary CT angiography (CCTA). Methods: Totally 156 patients of suspected coronary artery disease who underwent CCTA with prospective ECG-triggering were involved. The patients were divided into regular kilovoltage group (n=103) scanned with noise-based tube current and normal kilovoltage (120 kV), and low kilovoltage group (n=53) scanned with noise-based tube current and low kilovoltage (100 kV). Image quality, CT value, noise, SNR, CNR and radiation dose were compared between the two groups. Results: In low kilovoltage group, image quality score, CT value, noise, SNR and CNR value were all higher than those in regular kilovoltage group (all P<0.05). There was no significant difference in radiation dose between the two groups. Conclusion: Noise-based low tube current scanning combined with low kilovoltage can not only decrease radiation dose but also improve image quality in CCTA. Copyright © 2013 by the Press of Chinese Journal of Medical Imaging Technology.