Background: Increased use of pediatric computed tomography (CT) raises concerns about cancer risk from ionizing radiation. We explored trends in pediatric CT use over time, estimated radiation exposure and cancer risk associated with pediatric CT, and projected the number of radiation-induced cancers that could be potentially prevented by dose-reduction strategies.
Methods: We evaluated CT use among children under 15 years at six US integrated healthcare systems from 1996-2010, including 4,857,736 patient-years. We calculated organ and effective doses for 711 randomly selected CT examinations performed from 2001-2011 and projected the corresponding lifetime attributable risks of cancer. National numbers of radiation-induced cancers from pediatric CTs were projected using observed and standardized doses.
Results: Pediatric CT use more than doubled between 1996 and 2005, stabilized until 2007, then declined. Effective doses varied widely from 0.1 to 72.7 mSv per scan. Among children 10-14 years, 42% of abdomen/pelvis CTs and 6% of chest CTs delivered an effective dose =20mSv. Projected lifetime attributable risks of solid cancers were higher for girls than boys and were highest for abdomen/pelvis CTs, ranging from 2.0-43.9 cancers /10,000 CTs. In girls, a radiation-induced solid cancer is projected to result from every 230-260 abdomen/pelvis CTs, 280-370 chest CTs, and 360-820 spine CTs, depending on age. Leukemia risk was highest for head CT. Nationally, 6.7 million pediatric CTs performed each year are projected to result in 9940 future cancers. Reducing the highest 25% of doses to the median might prevent 38% of these cancers.
Conclusions: Increased use of pediatric CT combined with wide variability in radiation dose has resulted in many children receiving a relatively high-dose examination. Dose-reduction strategies targeted to the highest quartile of doses could dramatically reduce the number of radiation-induced cancers.