Reference Values: A Metric for Controlling CT Dose

The concept of reference values arose from the fact that computed tomography (CT) doses used in clinical practice can vary widely (Wall and Shrimpton 1998, Shrimpton et al. 2005). Reference values for maximum CT dose are developed from dose surveys by assuming that any dose in the top 25% of a survey is probably unnecessarily high and that doses should be kept below that level.