Which term describes an x-ray component placed in the primary beam to preferentially absorb or eliminate the less penetrating x-rays before they reach the patient?

• A. Grid
• B. Collimator
• C. Added filtration
• D. Inherent shielding

Answer: (C)

Removing the lower-energy photons before they reach the patient is accomplished by filtration, which hardens the beam and reduces patient dose while preserving image quality. The term described is added filtration: an extra sheet of absorbing material placed in the path of the primary beam (usually aluminum) that preferentially absorbs those less penetrating photons. This works because low-energy photons contribute more to absorbed dose yet add little useful image information, so removing them improves contrast and reduces skin dose. Inherent filtration is what the tube already has inside, and you can add more filtration beyond that as needed. The other options don’t fit: a grid sits between the patient and detector to remove scatter, not to filter beam energy; a collimator shapes the beam but doesn’t change its energy spectrum; inherent shielding refers to protective barriers rather than a component placed in the beam path.