Children with heart disease are cumulatively exposed to relatively low levels of ionizing radiation from imaging procedures – less than the average annual background exposure in the United States – although those who have undergone more complex procedures such as heart transplants or cardiac catheterization experience significantly greater exposure, a retrospective cohort study has found.
Dr. Jason N. Johnson, a pediatric cardiologist at Duke University Medical Center, Durham, N.C., and his colleagues showed that the estimated lifetime attributable risk of cancer above baseline ranged from 6 cases per 100,000 exposed for children with atrial septal defect, to 1,677 per 100,000 exposed for cardiac transplant, with a median of 65 cases per 100,000 across surgical cohorts.
While conventional radiographic examination accounted for 92% of the total examinations, it accounted for only 8% of the cumulative effective dose, compared with cardiac catheterization, which represented 1.5% of all examinations but accounted for 60% of the total radiation exposure, according to a study published online June 9 in Circulation.
The study of 337 children aged 6 years or younger exposed to more than 13,000 radiation examinations found the lifetime attributable risk of cancer was nearly double in females versus males, mostly because of increased breast and thyroid cancer risk (Circulation 2014 June 9 [doi:10.1161/CIRCULATIONAHA.113.005425]).
The study was funded by grants from the National Institutes of Health and the Mend a Heart Foundation. One author reported receiving support from the U.S. Nuclear Regulatory Commission, the U.S. Department of Energy, and Duke University.