Inherent filtration refers to filtration located in which part of the x-ray assembly?

• A. Outside the housing on the collimator
• B. In the x-ray tube and housing
• C. Within the patient path of travel
• D. In the developing room

Answer: (B)

Inherent filtration is filtration that is built into the x‑ray tube assembly itself, not something you add in the beam path. It resides inside the tube components—the glass envelope, dielectric oil, and the metal housing—so low-energy photons are attenuated before the beam exits the tube. This filtration is fixed and part of the tube design, which is why it’s considered inherent.

Filtration placed outside the housing, such as on the collimator, is added filtration and can be adjusted or removed. Filtration somewhere along the patient’s path or in the developing room isn’t about the beam’s filtration at the source, so it doesn’t describe inherent filtration.