How is the x-ray beam changed by the addition of one HVL of filtration?

How is the x-ray beam changed by the addition of one HVL of filtration?

• A. 50% increase in quantity
• B. 50% decrease in quantity
• C. 50% increase in quality
• D. 50% decrease in quality

Answer: (B)

One HVL of filtration is defined as the thickness of material that cuts the beam’s intensity in half. So when you add one HVL, the number of photons reaching the detector or patient is reduced to 50% of what it was before—that’s a 50% decrease in beam quantity. Filtration also removes more of the low-energy photons, which shifts the spectrum toward higher energies and makes the beam harder (higher quality), but the explicit change described by one HVL is a halving of the beam intensity.

One HVL of filtration is defined as the thickness of material that cuts the beam’s intensity in half. So when you add one HVL, the number of photons reaching the detector or patient is reduced to 50% of what it was before—that’s a 50% decrease in beam quantity. Filtration also removes more of the low-energy photons, which shifts the spectrum toward higher energies and makes the beam harder (higher quality), but the explicit change described by one HVL is a halving of the beam intensity.