Which type of radiation effect has a defined threshold dose?

• A. Deterministic
• B. Stochastic
• C. Both have thresholds
• D. Neither

Answer: (A)

Deterministic effects are tissue reactions that require a certain dose before they can appear. Below a defined threshold, no effect is seen; once the threshold is surpassed, the effect occurs and its severity tends to increase with higher doses. That’s why this type of radiation effect has a defined threshold dose.

Stochastic effects, like cancer or genetic mutations, do not have a fixed dose at which they begin. The probability of occurrence rises with dose, but there isn’t a safe cutoff where the effect suddenly starts; hence no threshold.

So the correct choice reflects that deterministic effects have a defined threshold, while stochastic effects do not.