What effect does increasing the peak kilovoltage (kVp) have on patient dose and image quality?

What effect does increasing the peak kilovoltage (kVp) have on patient dose and image quality?

• A. Increases the patient dose and improves image contrast.
• B. Decreases the patient dose while maintaining acceptable image quality (though contrast may be reduced).
• C. Has no effect on the patient dose.
• D. Always increases the patient dose.

Answer: (B)

Raising the peak kVp increases the energy of the x-ray photons, so the beam becomes more penetrating. That reduces the difference in attenuation between different tissues, which lowers image contrast. At the same time, because the beam is more penetrating, you can achieve the same receptor exposure with fewer photons, meaning you can lower the mAs and thus reduce the dose to the patient. If you keep the image within diagnostic needs, the image remains acceptable even though the contrast is slightly reduced. The other options don’t fit: higher kVp doesn’t inherently raise dose or guarantee better contrast, and it does affect the dose.

Raising the peak kVp increases the energy of the x-ray photons, so the beam becomes more penetrating. That reduces the difference in attenuation between different tissues, which lowers image contrast. At the same time, because the beam is more penetrating, you can achieve the same receptor exposure with fewer photons, meaning you can lower the mAs and thus reduce the dose to the patient. If you keep the image within diagnostic needs, the image remains acceptable even though the contrast is slightly reduced. The other options don’t fit: higher kVp doesn’t inherently raise dose or guarantee better contrast, and it does affect the dose.