Minimum total filtration (inherent plus added) required in equipment operated above 70 kVp?

Minimum total filtration (inherent plus added) required in equipment operated above 70 kVp?

• A. 0.5 mm Al
• B. 2.5 mm Al
• C. 1.0 mm Al
• D. 5.0 mm Al

Answer: (B)

Filtration is used to remove low-energy photons from the beam, which would add patient dose without improving image quality and also helps harden the beam, increasing beam quality and the HVL. For diagnostic x-ray beams operated above 70 kVp, the total filtration must be at least 2.5 mm aluminum equivalence. The tube already has about 0.5 mm Al of inherent filtration, so added filtration must provide at least 2.0 mm Al to reach the required total. That’s why 2.5 mm Al is the minimum total filtration. The other values don’t meet this regulatory requirement (too little) or would unduly reduce beam intensity (too much).

Filtration is used to remove low-energy photons from the beam, which would add patient dose without improving image quality and also helps harden the beam, increasing beam quality and the HVL.

For diagnostic x-ray beams operated above 70 kVp, the total filtration must be at least 2.5 mm aluminum equivalence. The tube already has about 0.5 mm Al of inherent filtration, so added filtration must provide at least 2.0 mm Al to reach the required total. That’s why 2.5 mm Al is the minimum total filtration. The other values don’t meet this regulatory requirement (too little) or would unduly reduce beam intensity (too much).