Correct collimation can increase image quality due to a decrease in:

• A. bremsstrahlung radiation
• B. geometric distortion
• C. scatter radiation
• D. geometric magnification

Answer: (C)

Limiting the x-ray field through proper collimation reduces the volume of tissue irradiated, which lowers the amount of scatter radiation that reaches the image receptor. Scatter acts like fog, reducing image contrast and overall quality, so cutting it down leads to a crisper, higher-contrast image. Bremsstrahlung production occurs in the tube and isn’t directly affected by collimation once the beam is formed, so it doesn’t explain the improvement. Geometric distortion and magnification depend on distances and alignment in the setup, not field size, so they’re not controlled by collimation. The image quality gain from collimation comes from the decrease in scatter radiation.