Which effect does increasing the source-to-receptor distance have besides decreasing beam divergence?

Which effect does increasing the source-to-receptor distance have besides decreasing beam divergence?

• A. It yields a sharper image.
• B. It increases magnification without clarity change.
• C. It increases beam intensity.
• D. It reduces patient dose.

Answer: (A)

Increasing the source-to-receptor distance reduces geometric unsharpness, so the edges on the image become crisper. As SID grows, magnification decreases and the penumbra blur shrinks, which together yield a sharper image. The distance does not increase image sharpness by boosting beam intensity; in fact, beam intensity at the receptor falls off with distance, and maintaining brightness would require higher exposure factors (which can offset any dose savings). It also does not produce more magnification—farther distance actually reduces magnification.