The total amount of irradiated material is a function of which factors?

• A. Patient age and gender
• B. Body part thickness and area of exposure
• C. Exposure time and beam quality
• D. Field size and shielding

Answer: (B)

The amount of tissue exposed depends on the volume being irradiated, which is determined by how large the exposed field is and how thick the part is. A larger field size increases the surface area of tissue that the beam passes through, while greater thickness means more tissue lies in the beam’s path. Together, they define how much material is irradiated. Exposure time and beam quality affect the dose delivered within that volume, but not how much tissue is irradiated itself. Shielding can reduce the exposed area, and patient age or gender don’t change the basic geometry of the exposure.