The objective of the study was to estimate the increased lifetime cancer risk associated with a single computed tomography (CT) examination for calculus detection in pediatric patients and compare it with the lifetime natural cancer risk.
We used the program CT-Expo to calculate the radiation doses to various abdominal and pelvic organs for age-appropriate pediatric renal stone CT examination protocols used at our institution. Using the Biological Effects of Ionizing Radiation (BEIR) VII report, we estimated the lifelong cancer risk for these organs and compared it with the natural cancer risk for the same organs as predicted by the Surveillance, Epidemiology and End Results data from the National Cancer Institute.
For children 10 years or younger at the time of the examination, about 3 radiation-induced cancers are predicted for every 1000 naturally occurring cancers, and for children 15 years old, about 2 radiation-induced cancers are predicted for every 1000 naturally occurring cancers. The radiation dose from this examination is approximately equivalent to 1 to 2 years of background radiation.
The ratio of the risk for any abdominal and pelvic cancer due to a single CT examination for calculus detection to the risk of a naturally occurring cancer over the lifetime of a child is estimated to be 2/1000 to 3/1000. With this information, the emergency department pediatrician can more effectively counsel parents about the risk-benefit aspects of the CT examination for renal calculus disease in their children.