Which statement about dose is true?

Which statement about dose is true?

• A. Increasing kVp, mA, or exposure time increases patient dose.
• B. Only increasing mA increases dose.
• C. Exposure time has no effect on dose.
• D. Increasing kVp always increases image sharpness.

Answer: (A)

Dose to the patient is driven by how much energy the X-ray beam delivers, which comes from the exposure factors you set. Raising the tube current (mA) increases the number of photons produced each second, so more energy reaches the patient. Extending the exposure time adds more photons overall, again delivering more energy and increasing dose. Increasing the beam energy with higher kVp makes each photon more energetic and can raise the total energy deposited in tissues, so dose tends to go up as kVp increases (even though image contrast changes in the process). Because of this, increasing any of these factors typically raises patient dose, which is why that statement is true. The other options don’t fit: increasing only mA ignores the contributions from exposure time and kVp; exposure time does affect dose; and increasing kVp does not guarantee sharper images—sharpness is mainly dictated by geometric factors and filtration, not by kVp alone.

Dose to the patient is driven by how much energy the X-ray beam delivers, which comes from the exposure factors you set. Raising the tube current (mA) increases the number of photons produced each second, so more energy reaches the patient. Extending the exposure time adds more photons overall, again delivering more energy and increasing dose. Increasing the beam energy with higher kVp makes each photon more energetic and can raise the total energy deposited in tissues, so dose tends to go up as kVp increases (even though image contrast changes in the process). Because of this, increasing any of these factors typically raises patient dose, which is why that statement is true.

The other options don’t fit: increasing only mA ignores the contributions from exposure time and kVp; exposure time does affect dose; and increasing kVp does not guarantee sharper images—sharpness is mainly dictated by geometric factors and filtration, not by kVp alone.