CAMRT Radiography Practice Exam

What effect does increased filtration have on patient dose when other factors are kept constant?

1. Increased dose

2. Decreased dose

3. No effect on dose

4. Variable effect depending on equipment

The correct answer is: Decreased dose

Increased filtration in radiography serves to selectively reduce the lower-energy x-ray photons that contribute to patient dose. When other factors, such as the exposure time, tube current, and voltage, remain constant, filtration primarily acts to improve the quality of the x-ray beam by allowing higher-energy photons to pass through while absorbing the less penetrating, lower-energy photons. Lower-energy photons are less likely to contribute to diagnostic quality images, as they are often absorbed by the patient's tissues rather than reaching the imaging receptor. By filtering out these photons, the overall dose the patient receives is diminished, leading to a decrease in the amount of radiation exposure. Additionally, while higher filtration can reduce patient dose, it may necessitate an increase in exposure factors to maintain image quality, potentially offsetting some dose reduction. However, this interplay generally results in a net reduction of patient dose. Understanding how filtration improves beam quality while minimizing unnecessary radiation exposure is critical in radiographic practice, aligning with the principles of radiation protection and patient safety.