Radiation from Computed Tomography Scans Increase Cancer Risk in Children

Pediatric computed tomography (CT) scans have become standard for many diagnostic evaluations. In 2011, an estimated 4.25 million CT scans were performed in children in the U.S. The average CT scan delivers a radiation dose (2.34 mSv) equivalent to approximately 200 standard chest x-rays. Two studies estimate cancer risk following radiation exposure in children.

In a data linkage study of CT exposure and subsequent cancer diagnoses in nearly 11 million children (age range, 0–19 years) born between 1985 and 2005 in Australia, 6% had at least one CT and 60,674 children were diagnosed with cancer >1 year after exposure. At a mean of 9.5 years after exposure, the incidence of any cancer was 24% higher in the CT group than in the unexposed group, and the incidence rate ratio increased by 0.16 for each additional scan. Risks were similar 5 and 10 years after exposure and after excluding brain cancers. The average collective radiation dose to all organs was 4.5 mSv per scan. Risks were highest for brain cancer and in children <5 years.

In the second study, investigators examined trends in CT imaging, radiation exposure, and cancer risk in children <15 years from seven diverse U.S. health systems. CT use doubled between 1996 and 2005, stabilized in 2006–2007, and declined 14% by 2010. Radiation doses were highest for abdominal/pelvic scans. Bone marrow doses were highest for head CT scans in children <5 years and abdominal/pelvic scans in children aged 10–14 years. Solid cancer risk was higher for girls than boys and following abdominal/pelvic scans (26–34 cancers/10,000 scans). Risk for leukemia was highest after head CT in children <10 years. The authors estimate that 4870 future cancers in the U.S. were generated by pediatric CT in 2011.