How does increasing kilovoltage peak (kVp) affect the amount of Compton scatter striking the image receptor?

• A. Increasing kVp increases scatter striking the receptor
• B. Increasing kVp decreases scatter striking the receptor
• C. Increasing kVp has no effect on the scatter striking the receptor
• D. Increasing kVp reduces receptor exposure due to absorption

Answer: (A)

Increasing kVp raises the energy of the x-ray photons, which shifts tissue interactions from mainly photoelectric absorption toward Compton scattering. When Compton scatter occurs, photons exit the patient in many directions, and some of these scattered photons reach the image receptor. As kVp increases, more photons undergo Compton interactions, so more scatter reaches the receptor. This is why higher kVp not only reduces image contrast but also increases the amount of scatter striking the receptor. The idea that scatter would stay the same or decrease doesn’t fit because the energy-dependent balance of interactions favors more scatter at higher voltages, and higher energy photons are less likely to be absorbed and more likely to penetrate or scatter toward the receptor.