The relationship between kVp and receptor exposure is:

The relationship between kVp and receptor exposure is:

• A. Indirect
• B. Directly proportional
• C. Direct, although not proportional
• D. Inverse

Answer: (C)

Increasing kVp makes the x-ray beam more penetrating, so a larger fraction of photons reach the receptor and receptor exposure rises even when mAs is held constant. However, this rise is not a straight one-for-one increase. The photon flux (how many photons are produced) is largely set by mAs, while kVp changes the energy spectrum and how photons interact with patient tissues. As energy climbs, more photons pass through with less attenuation, but the relationship between exposure and kVp is non-linear because the probabilities of photoelectric absorption and Compton scattering change with energy and tissue thickness, and the detector’s response to different energies isn’t perfectly linear. So receptor exposure does increase with kVp, but not in direct proportional fashion.

Increasing kVp makes the x-ray beam more penetrating, so a larger fraction of photons reach the receptor and receptor exposure rises even when mAs is held constant. However, this rise is not a straight one-for-one increase. The photon flux (how many photons are produced) is largely set by mAs, while kVp changes the energy spectrum and how photons interact with patient tissues. As energy climbs, more photons pass through with less attenuation, but the relationship between exposure and kVp is non-linear because the probabilities of photoelectric absorption and Compton scattering change with energy and tissue thickness, and the detector’s response to different energies isn’t perfectly linear. So receptor exposure does increase with kVp, but not in direct proportional fashion.