Two national trends have preoccupied Caleb Nelson, MD, MPH, and his colleagues in the Boston Children’s Hospital’s Urology Department over the past few years. One is the rise in overall exposure to medical radiation. The second is specifically the increased use of computed tomography (CT) scans—rather than clinician-preferred ultrasound—in children with kidney stones.

“We see a lot of kids with stones, and there is a clinical need to better manage their condition,” Nelson explains. “Medical radiation is a risk factor for problems down the road, and we know that the amount of radiation people are receiving has gone through the roof in recent years.”

How big is the problem? Nelson cites data collected on radiation exposure on the U.S. population from 1987 to 2006 by the National Council on Radiation Protection and Measurements (NCRP). At the beginning of the study, about 18 percent of all radiation exposure was medical. By 2006, that number had grown to 48 percent (see chart below). …