Radiology: Volume 261: Number 1 - October 2011
E. Stephen Amis, Jr., MD
There is no marker, histologic or otherwise, that identifies a cancer as being radiation induced as opposed to arising de novo. Yet increased cancer risk, as a stochastic effect of exposure to ionizing radiation, is universally accepted primarily on the basis of long-term studies of survivors of the atomic bombing or Japan. Estimations of these cancer risks are derived from modeling of data generated by examining surviving victims who were at varying distances from the epicenter of the blast and who were exposed to whole-body doses of both particulate and electromagnetic ionizing radiation. Given that computed tomography (CT) involves the controlled exposure of limited areas of the body to x-radiation alone, there are many uncertainties in generalizing the data from Japan to cancer risk related to imaging in the U.S. population. The Biological Effects of Ionizing Radiation (BEIR) VII report (1), which was based largely on data in Japanese atomic bombing survivors but also took into account some of the potential inaccuracies, has become the accepted reference for assigning cancer risk in individuals of all ages and both sexes who are exposed to low levels of ionizing radiation.