This worrying article from Australia of a matched database study shows a significant increase in cancer risk with a CT scan performed during childhood or adolescence, (Mathews JD, Forsythe AV, Brady Z, Butler MW, Goergen SK, Byrnes GB, Giles GG, Wallace AB, Anderson PR, Guiver TA et al: Cancer risk in 680 000 people exposed to computed tomography scans in childhood or adolescence: data linkage study of 11 million Australians. BMJ 2013, 346(may21 1):f2360-f2360.) The increase in incidence is about 24% over the population baseline risk, which is not huge for a relatively infrequent group of diseases, but the follow up of the population was just under 10 years on average, so it might increase as time goes on. That’s about 10 cancers per 100,000 patient years at risk, so don’t panic yet!
Premature babies have a lot of radiographs, and get exposed to a lot of radiation. Donadieu J, Zeghnoun A, Roudier C, Maccia C, Pirard P, Andre C, Adamsbaum C, Kalifa G, Legmann P, Jarreau P-H: Cumulative effective doses delivered by radiographs to preterm infants in a neonatal intensive care unit. Pediatrics 2006, 117(3):882-888. But most of them are way below what you get from a CT scan, even if you add up all the radiation during their entire stay. A few get to quite high levels however, and some of them do end up with a CT scan. Need to consider carefully each time before a CT scan if the very small increase in risk of cancer is worth the clinical information that we will get.