To the Editor The important article1 by Miglioretti et al and accompanying editorial2 demonstrating increased cancer risks from certain computed tomography exposures appropriately emphasize the need to minimize numbers and dosages of radiation studies in children. Not mentioned is the possibility of assessing radiation sensitivity in the subject, an aspect of personalized medicine that might be added to hemoglobin or lead levels during early well-child care: give children an index of radiation susceptibility analogous to the dosimeter badges of radiation-exposed workers. Because of the remarkable complexity and controversy regarding conversion of radiation exposure into disease risk, I suggest a spotlight issue on pediatric radiation effects that covers molecular mechanisms of radiation damage, dosage measures, and potential molecular assays that can bridge the chasm between radiation exposure and disease risk.