American Registry of Radiologic Technologists (ARRT) Practice Exam

Which of the following is not classified as a stochastic effect of radiation?

1. Malignancy

2. Acute radiation syndrome

3. Leukemia

4. Genetic effects

The correct answer is: Acute radiation syndrome

Stochastic effects of radiation are those that occur by chance and are typically associated with low doses of radiation over a long period of time. They do not have a threshold level of exposure, meaning that the risk increases with an increasing dose, but even small amounts of radiation can contribute to the risk of these effects. Malignancy, leukemia, and genetic effects are all examples of stochastic effects because they arise from cellular damage that may occur randomly and result in cancerous changes or hereditary mutations. Acute radiation syndrome, on the other hand, is considered a deterministic effect. This type of effect is characterized by a threshold dose; it occurs after a high dose of radiation in a short time frame, typically leading to clear and immediate symptoms such as nausea, vomiting, and in severe cases, death. The severity of acute radiation syndrome is directly related to the dose received, which differentiates it from stochastic effects, where the effects might manifest later and do not depend on dose in a linear manner. Understanding this distinction is important for recognizing the different types of effects radiation can have on human health, especially in the context of radiation safety and risk assessment.