Fetal exposure, in excess of which level, warrants possible termination of a pregnancy?

• A. 100 mGy.
• B. 50 mGy.
• C. 250 mGy.
• D. 150 mGy.

Answer: (C)

Exposure of a developing fetus to ionizing radiation carries deterministic risks that grow with dose. The most significant potential outcomes—such as fetal death, major congenital malformations, and neurodevelopmental problems—have dose thresholds. When the estimated fetal dose reaches about 250 mGy (a quarter of a gray), the chance of serious deterministic effects becomes substantial enough that termination may be considered, depending on gestational age and the clinical context. Lower exposures, like 50–150 mGy, carry a much smaller risk of these effects, so termination is not typically prompted by dose alone. In practice, the emphasis is on minimizing exposure and assessing each case individually; 250 mGy is a commonly cited threshold at which the risk becomes serious enough to discuss possible termination.