Objective: To retrospectively analyze the diagnostic image quality and estimated radiation dose of the three coronary computed tomographic angiography( CCTA) acquisition protocols in a recently introduced second generation dual-source computed tomography. Methods: A total of 407 subjects underwent dual-source CCTA by using high-pitch spiral,sequential and retrospective spiral protocols. Effective radiation dose,expressed was calculated as the product of the dose-length product times a conversion factor of0....