For measuring scatter radiation during fluoroscopy, what dosimeter position will demonstrate the lowest exposure rate?

• A. 1 meter from the patient
• B. 2 meters from the patient
• C. 3 meters from the patient
• D. dosimeter position does not affect the exposure rate

Answer: (C)

Scatter radiation behaves like a source centered on the patient, and its intensity falls off quickly as you move away. This happens because photons spread over a larger area and the geometric dilution follows the inverse square principle. So the farther the dosimeter is from the patient, the lower the exposure rate it will register. Among the distances given, three meters is the farthest, so it will show the lowest reading. The other distances—closer to the patient—will show higher scatter exposure, and saying distance doesn’t affect the reading isn’t correct because geometry directly changes how much scatter reaches the dosimeter.