Most occupational exposure comes from which source?

• A. Direct exposure to the primary beam
• B. Leakage radiation
• C. Scattered radiation
• D. Stray radiation minus scattered radiation

Answer: (C)

Scattered radiation from the patient is the main source of occupational exposure in diagnostic radiography. The primary beam is aimed at the patient to create the image, but you’re not standing in that direct path. Tube leakage and stray radiation exist, but tube design and shielding keep them at relatively low levels. The photons that scatter off the patient, however, radiate in many directions, and since the operator is typically close to the patient during procedures, those scattered photons reach you in greater numbers than leakage or stray photons. Therefore, scatter is the dominant contributor to the dose you receive.

To reduce exposure, maximize distance when possible, use shielding such as lead aprons and barriers, and optimize imaging techniques to limit scatter (collimate tightly and use appropriate kVp/mAs).