What thickness of aluminum filter should be used for x-rays greater than 70 kV?

The use of a 2.5mm aluminum filter for x-rays greater than 70 kV is essential to ensure adequate filtration. This thickness effectively removes low-energy photons from the x-ray beam, which could contribute to patient dose without improving image quality. By filtering out these lower-energy x-rays, the overall quality of the x-ray image is improved, as only the higher-energy, more penetrating x-rays reach the film or digital detector.

Standards set by organizations such as the National Council on Radiation Protection and Measurements (NCRP) specify that equipment operating above 70 kV must incorporate at least 2.5mm of aluminum or equivalent filtering. This regulation is in place to promote patient safety by minimizing unnecessary radiation exposure while still allowing sufficient diagnostic information to be captured through the x-ray imaging process. Effective filtration becomes increasingly important at higher kilovoltages, as the proportion of low-energy x-rays in the beam increases, necessitating the use of thicker filters to maintain a balance between diagnostic efficacy and patient safety.