Which parameter is used to assess beam filtration adequacy in QA?

• A. Timer accuracy
• B. Receptor alignment checks
• C. HVL/filtration adequacy
• D. Beam alignment

Answer: (C)

Filtration adequacy is assessed by measuring the HVL, the half-value layer, which reflects how effectively the beam has been hardened by filtration. In QA, filtration removes low-energy photons that add patient dose without improving image quality. The HVL is the thickness of a material (usually aluminum) needed to reduce the X-ray beam intensity by half at the chosen kVp. If the HVL is too low, filtration is insufficient, increasing patient skin dose and degrading image contrast. If the HVL is too high, filtration may be excessive, reducing beam intensity and possibly requiring higher exposure to achieve adequate receptor signal. Other checks like timer accuracy, receptor alignment, and beam alignment affect exposure timing and geometry but do not directly measure filtration quality.