ABSTRACT
Concerns have also been raised about the possibility of cancer induction in children exposed to intrauterine radiation. Unlike death or malformation, the induction of cancers is believed to be a dose-response rather than threshold phenomenon. Because childhood cancers are rare events, even a doubling or quadrupling of the risk has little impact on cancer deaths. Excess risk of fatal childhood cancer attributed to fetal exposure with typical diagnostic procedures range from 1 in 30,000 to 1 in 1700. The derived risk is estimated at 1 excess case per 33,000 per mGy of exposure. The highest risks, which remain quite small on a population basis, are seen with the highest exposures, for example, CT of the pelvis (33). This concern is not a reason to routinely offer termination of pregnancy (33,39). Recent estimates of conceptus radiation dose with a single anteroposterior chest radiograph (assuming an average maternal size: dose increases with increasing maternal size) range from 0.0021 to 0.0028 mGy in the first trimester to 0.1 to 5.9 mGy in the second and 0.1 to 1.9 mGy in the third trimester (40). This corresponds to an excess risk of childhood cancer of approximately 10 per million.
