What is the purpose of filtration in dental X-ray beams?

• A. Remove high-energy photons to reduce beam quality.
• B. Remove low-energy photons, increasing beam quality and reducing patient skin dose.
• C. Increase beam intensity.
• D. Expand the beam field.

Answer: (B)

Filtration works by removing the soft, low-energy photons from the X-ray beam. Those low-energy photons are absorbed easily by superficial tissues, contributing little to image formation but delivering dose to the skin. By filtering them out, the beam’s average energy (beam quality) increases, producing a harder beam that penetrates more efficiently while reducing the patient’s skin dose. In dental units this filtration comes from the tube housing (inherent filtration) plus added filtration such as aluminum. This keeps image quality adequate while lowering unnecessary exposure.