American Society of Radiologic Technologist (ASRT) Practice Exam

The curve below represents which type of relationship?

1. Linear nonthreshold

2. Linear threshold

3. Linear quadratic

4. Linear stochastic

The correct answer is: Linear threshold

The curve representing a linear threshold relationship indicates that there is a specific level of exposure before any detectable effect or response occurs. In this type of relationship, the risk of an effect begins to increase only after the exposure surpasses a certain threshold. This concept is fundamental in understanding dose-response relationships in radiology and radiation safety, as it suggests that lower levels of exposure may not result in any harm or biological effect, thereby allowing for a threshold level where safety measures can be implemented effectively. In contrast, other relationships, such as linear nonthreshold, would imply that any amount of exposure could lead to some degree of biological effect without a safe threshold, while linear quadratic and linear stochastic relationships describe different types of responses to increasing doses, often considering varying degrees of risk or non-linear effects.