Increasing aluminum filtration from 3.0 to 3.5 mm Al would result in which one of the following changes to receptor exposure?

Increasing aluminum filtration from 3.0 to 3.5 mm Al would result in which one of the following changes to receptor exposure?

• A. Increased receptor exposure
• B. Decreased receptor exposure
• C. Increased patient skin dose
• D. No change in receptor exposure

Answer: (B)

Increasing aluminum filtration removes low-energy photons from the beam. These soft photons contribute little to the image but add dose to the patient, so filtering them out makes the beam harder and reduces the overall number of photons that reach the image receptor if exposure factors stay the same. That drop in photon fluence translates to decreased receptor exposure. To keep the same receptor exposure after adding filtration, you’d need to raise exposure factors (for example, increase mA or exposure time) to compensate. The result of more filtration, therefore, is a lower receptor exposure unless technique is adjusted.

Increasing aluminum filtration removes low-energy photons from the beam. These soft photons contribute little to the image but add dose to the patient, so filtering them out makes the beam harder and reduces the overall number of photons that reach the image receptor if exposure factors stay the same. That drop in photon fluence translates to decreased receptor exposure. To keep the same receptor exposure after adding filtration, you’d need to raise exposure factors (for example, increase mA or exposure time) to compensate. The result of more filtration, therefore, is a lower receptor exposure unless technique is adjusted.