Which combination is not appropriate for dose reduction?

• A. High kVp, low mAs
• B. Low kVp, high mAs
• C. High kVp, high mAs
• D. Low kVp, low mAs

Answer: (C)

The idea being tested is dose optimization through technique selection: using higher kVp with lower mAs to keep receptor exposure while reducing the patient’s dose. mAs controls the total number of photons reaching the patient, so lowering mAs reduces dose. Increasing kVp raises photon energy and penetration, which allows you to use a lower mAs to achieve the same receptor exposure, often with a trade-off of lower image contrast but with less dose.

The combination that is not appropriate for dose reduction is the one with high kVp and high mAs. Even though the beam is energetic, the high mAs means many photons are produced and reach the patient, driving a higher dose. In contrast, high kVp with low mAs lowers dose, and low kVp with low mAs minimizes dose though it may affect image quality. Low kVp with high mAs would still increase dose significantly, but the key point here is that pairing high kVp with high mAs fails the dose-reduction goal because the mAs portion dominates the dose.