radiation exposure from cT scans : How to Close Our Knowledge Gaps , Monitor and Safeguard Exposure — Proceedings and Recommendations of the Radiation Dose Summit , Sponsored by NIBIB , February 24 – 25 , 20111

John M. Boone, PhD William R. Hendee, PhD Michael F. McNitt-Gray, PhD Steven E. Seltzer, MD This article summarizes the proceedings of a portion of the Radiation Dose Summit, which was organized by the National Institute of Biomedical Imaging and Bioengineering and held in Bethesda, Maryland, in February 2011. The current understandings of ways to optimize the benefit-risk ratio of computed tomography (CT) examinations are summarized and recommendations are made for priority areas of research to close existing gaps in our knowledge. The prospects of achieving a submillisievert effective dose CT examination routinely are assessed.