Which interaction is associated with increased occupational dose during radiography?

• A. Photoelectric absorption
• B. Coherent scattering
• C. Compton scattering
• D. Pair production

Answer: (C)

In radiography, the amount of scattered radiation that escapes the patient and can reach the operator largely determines occupational dose. Compton scattering is the main source of that scatter in the diagnostic energy range. When the x-ray photon collides with loosely bound outer electrons, it transfers part of its energy to the electron and is scattered as a lower-energy photon in a new direction. These scattered photons travel in all directions, including toward the radiographer, and are a major contributor to workplace exposure. Photoelectric absorption mostly takes place in the patient and leaves fewer photons to escape; coherent scattering is relatively rare and involves minimal energy transfer; pair production only becomes significant at much higher energies than those used in typical diagnostic imaging. So, Compton scattering is the interaction most associated with increased occupational dose because it generates the substantial scatter radiation that can reach the radiographer.