DANB Radiation Health and Safety (RHS) Practice Exam

What effect does increasing the distance from the radiation source to the film have on exposure?

1. Exposure increases

2. Exposure decreases

3. Exposure remains unchanged

4. Only affects large teeth

The correct answer is: Exposure decreases

Increasing the distance from the radiation source to the film decreases exposure due to the inverse square law of radiation. This law states that the intensity of radiation is inversely proportional to the square of the distance from the source. Therefore, as the distance from the radiation source increases, the amount of radiation that reaches the film decreases significantly. In practice, if you double the distance from the source to the film, you only receive one-fourth of the exposure that would have occurred at the original distance. This principle is critical in radiation safety and health, as it helps guide protocols for minimizing exposure to patients and operators in dental and medical settings. The other options do not accurately reflect the relationship between distance and radiation exposure, as exposure is not constant or increased with distance. Additionally, the impact of distance pertains to the overall exposure to radiation and is not limited to specific anatomy or tooth size.