Which statement about distance and scatter exposure during fluoroscopy is true?

Which statement about distance and scatter exposure during fluoroscopy is true?

• A. Exposure increases with distance
• B. Exposure decreases with distance
• C. Distance has no effect on exposure
• D. Exposure depends only on beam quality

Answer: (B)

Exposure decreases with distance because radiation intensity from an X-ray source falls off with the square of the distance (inverse square law). In fluoroscopy, the operator’s exposure mainly comes from scatter off the patient, and this scattered radiation also diminishes rapidly as you move farther away from the source and patient. Doubling the distance reduces the dose to about one-quarter, and increasing distance further reduces exposure even more. While beam quality and shielding matter, distance has a clear, protective effect, so the statement that exposure decreases with distance is the correct one.

Exposure decreases with distance because radiation intensity from an X-ray source falls off with the square of the distance (inverse square law). In fluoroscopy, the operator’s exposure mainly comes from scatter off the patient, and this scattered radiation also diminishes rapidly as you move farther away from the source and patient. Doubling the distance reduces the dose to about one-quarter, and increasing distance further reduces exposure even more. While beam quality and shielding matter, distance has a clear, protective effect, so the statement that exposure decreases with distance is the correct one.