Coronary computed tomography (CT) is one of the most rigorously tested imaging modalities. The history of evidence of coronary CT reflects the hierarchical model of efficacy of diagnostic imaging proposed by Fryback and Thornbury. Coronary CT has gone through technological evolution from electron beam CT to helical CT to multidetector CT. As technology improved, it also had to meet higher bars for evidence from proof of concept to diagnostic accuracy to evidence that it improves outcomes compared with its competitors.