Computed tomography scan radiation and brain cancer incidence.

For brain tumours that follow CT exposures in childhood by more than two years, we estimate that 40% (95%CI 29-50%) are attributable to CT radiation and not due to reverse causation. However, because of relatively low rates of CT exposure in Australia, only 3.7% (95% CI 2.3-5.4%) of all brain cancers are attributable to CT scans. The population attributable fraction will be greater in countries with higher rates of pediatric scanning.