Gilbert L. Raff, MD, FACC, FSCCT
Introduction
In 1965, Gordon Moore, the founder of Intel Corporation, famously predicted that the number of transistors on a computer chip would follow an exponential rise, doubling every 2 years (Fig. 1 A). Amazingly, this exponential growth has continued for >40 years. By contrast, for the past 5 years radiation exposure from coronary CT angiography has fol-lowed an inverse exponential path; doses reported by re¬search studies have declined by approximately 50% every 2 years (Fig. IB blue line). It is unclear how long this can be sustained, but current research reports document doses from coronary CT angiography that are lower than conven¬tional calcium scoring. The results from multicenter clinical practice surveys are also encouraging; although doses are considerably higher than research reports, the rate of change is similar (Fig. 1B red line). The objective of this review is to explore the evidence on radiation dose from coronary CT in published research, to define the gap between research and clinical practice, and to consider how this gap can be narrowed. The cancer risk from diagnostic medical radiation engenders concern and controversy. 1-7 Although this con¬cern encompasses medical imaging in general, computed tomography lies at the center of the debate, given the rise in the use of CT imaging. In response to particularly intense scrutiny over coronary CT angiography, vigorous research and development have resulted in the clinical release of 3 generations of novel scanner technology in 5 years, each