Which exposure setting should be used to increase the proportion of photoelectric interactions and decrease the proportion of Compton scattering interactions?

• A. 74 kilovoltage peak (kVp) and 16 milliampere-seconds (mAs)
• B. 87 kilovoltage peak (kVp) and 12 milliampere-seconds (mAs)
• C. 92 kilovoltage peak (kVp) and 6 milliampere-seconds (mAs)
• D. 110 kilovoltage peak (kVp) and 10 milliampere-seconds (mAs)

Answer: (A)

The amount of X-ray interactions changes with photon energy. Photoelectric absorption dominates at lower photon energies, especially in higher‑Z tissues, while Compton scattering becomes more likely as energy rises. So to tilt the mix toward more photoelectric interactions, you want a lower kVp. Because lowering energy reduces beam penetration, you compensate by increasing mAs to maintain similar image receptor exposure.

Among the given options, the setting with the lowest energy and the highest mAs best shifts toward photoelectric absorption and reduces the fraction of Compton scattering compared with the others. This makes photoelectric interactions more prominent while keeping the image exposure adequate.