What is the most commonly used filtration material in diagnostic radiography?

• A. Copper
• B. Molybdenum
• C. Aluminum
• D. Steel

Answer: (C)

Filtration in diagnostic radiography removes low-energy photons that would add patient dose without improving image quality. Aluminum is used most commonly for added filtration because its low atomic number efficiently attenuates those soft photons while preserving higher-energy photons that carry useful imaging information across a wide range of kVp. It’s also practical: inexpensive, easy to fabricate into filters, durable, non-toxic, and readily compatible with standard tube windows and shielding. Other materials, like molybdenum, are favored in specialized applications such as mammography to tailor the spectrum for that modality, while copper or steel would over-attenuate or cause other issues. So aluminum provides the best balance for general diagnostic imaging.