Clinical example of increasing source distance?

• A. Long PID.
• B. Short PID.
• C. Higher milliampere.
• D. Higher kilovolt peak.

Answer: (A)

Increasing the source-to-image distance is achieved by using a longer PID. When you place the x-ray source farther from the patient and image receptor, the beam spreads less as it reaches the receptor, which reduces geometric unsharpness and magnification. The result is a crisper image with finer detail, especially for small structures. In practice, a longer distance is a common technique to improve sharpness, though you may need to adjust exposure factors to maintain receptor brightness since beam intensity falls off with distance. The other options don't change the distance between the source and the image receptor—their effects are on beam quantity or energy, not on geometry.