The sum of inherent filtration and added filtration is called:

• A. Total filtration
• B. Net filtration
• C. Effective filtration
• D. Compensating filtration

Answer: (A)

Filtration in radiography is the process of removing low-energy photons to improve image quality and reduce patient dose. It has two parts: inherent filtration, which is built into the tube housing (such as the envelope, window, and insulating oil), and added filtration, which consists of aluminum sheets placed in the beam path. When these parts are combined, they yield the total filtration—the overall filtration of the beam as it leaves the tube. This total filtration determines the beam’s penetrating power and its dose characteristics (often reflected in the half-value layer). So the sum of inherent filtration and added filtration is total filtration. Other terms exist for different concepts (like compensating filtration used to balance exposure for patient thickness, or effective filtration which relates to how filtration changes beam quality in practice), but the direct sum of inherent and added filtration is defined as total filtration.