Which factor would decrease x-ray attenuation?

Which factor would decrease x-ray attenuation?

• A. Higher atomic number.
• B. Greater tissue density.
• C. Use of a negative contrast agent.
• D. High kilovolts peak (kVp) levels.

Answer: (D)

Raising kilovoltage peak increases the energy of the x-ray photons, making them more penetrating. Higher-energy photons interact less readily with matter, so fewer photons are absorbed or scattered as they pass through tissue. That means overall attenuation decreases. Keep in mind, though, that while attenuation goes down, image contrast can also decrease because the differences in attenuation between tissues become less pronounced. Higher atomic number and greater tissue density both raise attenuation because they increase the likelihood of interactions like photoelectric absorption and scattering. A negative contrast agent changes attenuation in the region where it’s present, but it doesn’t reduce attenuation across the beam everywhere, so it doesn’t produce the same global decrease as raising kVp.

Raising kilovoltage peak increases the energy of the x-ray photons, making them more penetrating. Higher-energy photons interact less readily with matter, so fewer photons are absorbed or scattered as they pass through tissue. That means overall attenuation decreases. Keep in mind, though, that while attenuation goes down, image contrast can also decrease because the differences in attenuation between tissues become less pronounced. Higher atomic number and greater tissue density both raise attenuation because they increase the likelihood of interactions like photoelectric absorption and scattering. A negative contrast agent changes attenuation in the region where it’s present, but it doesn’t reduce attenuation across the beam everywhere, so it doesn’t produce the same global decrease as raising kVp.