What effect does increasing filtration have on beam quality and patient dose?

• A. Filtration reduces patient dose while decreasing beam quality.
• B. Filtration has no effect on beam quality or dose.
• C. Filtration increases beam quality and reduces patient dose.
• D. Filtration reduces beam dose only if mA is also reduced.

Answer: (C)

Increasing filtration removes the soft, low-energy photons from the x-ray beam before it reaches the patient. Those low-energy photons contribute a lot to patient dose because they’re readily absorbed in superficial tissues, yet they don’t meaningfully improve image formation. By filtering them out, the remaining photons have higher average energy, so the beam quality is better (the HVL increases). Because the beam becomes harder and more penetrating, the patient dose is reduced for the same image receptor exposure. In practice, you may need to adjust technique to maintain receptor exposure, but the core effect is a harder beam with lower patient dose.