Which statement describes collimation's impact on dose?

• A. Increases patient dose by enlarging field
• B. Reduces patient dose by restricting the exposure field
• C. Has no effect on dose
• D. Only affects image sharpness

Answer: (B)

Collimation confines the x‑ray beam to the area of interest, so only that tissue is irradiated. Because dose is related to the amount of tissue exposed, narrowing the field reduces the overall patient dose. It also lowers scatter from tissues outside the target area, which improves image contrast and reduces unnecessary exposure. That’s why reducing the field to limit exposure directly lowers patient dose. The other ideas don’t fit: enlarging the field would raise dose, collimation does affect dose, and its benefits aren’t limited to image sharpness.