During a fluoroscopic examination of the upper GI tract with a 30 mGy dose to face/neck/chest/upper abdomen, which adverse effect is most likely?

• A. Skin erythema
• B. Epilation
• C. Diminished sperm count
• D. Cancer

Answer: (D)

The key idea is that cancer risk from radiation is a stochastic effect with no safe threshold, so even low doses can slightly increase lifetime cancer risk. A fluoroscopic exposure delivering about 30 mGy (0.03 Gy) to the upper body is far below the levels needed to cause immediate, deterministic skin injuries such as erythema or hair loss, which occur at doses on the order of grays. It also isn’t a dose high enough to reliably cause gonadal damage and reduced sperm count, since the testicular dose from this regional exposure would be relatively small unless the gonads were directly irradiated. Therefore the adverse effect most plausibly associated with this level of exposure is a small, probabilistic increase in cancer risk over a person’s lifetime, rather than an immediate tissue reaction.