What is filtration in X-ray production and why is it important?

• A. Filtration removes high-energy photons to improve image sharpness
• B. Filtration does not affect patient dose
• C. Filtration removes low-energy photons to reduce patient dose and improve beam quality
• D. Filtration increases scatter

Answer: (C)

Filtration removes the lowest-energy photons from the X-ray beam. Those soft photons would be absorbed quickly by the patient and contribute little to image formation, so removing them reduces patient dose while leaving the higher-energy photons that carry useful information. This “beam hardening” raises the average energy of the beam, improving beam quality and image contrast. Total filtration includes what’s built into the tube (inherent) plus what’s added (typically aluminum sheets), and it’s often described by the half-value layer. If filtration is increased, fewer photons reach the image receptor, so technique may need to be adjusted to maintain exposure, but the overall effect is lower dose and better image quality. The other statements aren’t correct because filtration mainly removes low-energy photons, it does affect patient dose, and it does not increase scatter.