Which of the following is a direct safety benefit of diagnostic filtration?

• A. Increase receptor exposure
• B. Increase patient dose
• C. Decrease patient dose
• D. Increase occupational dose

Answer: (C)

Diagnostic filtration works by removing the soft, low-energy photons from the X-ray beam before it reaches the patient. Those low-energy photons don’t contribute meaningful information to the image, but they are readily absorbed by superficial tissues and contribute to entrance skin dose and overall patient dose. By filtering them out, the beam becomes “harder,” the average photon energy increases, and the patient receives less dose for the same diagnostic image quality. This is a direct safety benefit because it lowers the radiation dose to the patient without compromising the image when technique is adjusted appropriately. The other outcomes—increasing receptor exposure or increasing occupational dose—do not occur as a direct result of diagnostic filtration; in practice, filtration tends to reduce scatter and patient dose, and any necessary technique adjustments can preserve image quality without raising exposure to staff.