Which component is primarily responsible for restricting the x-ray beam size and shape?

• A. Collimator.
• B. Protective housing.
• C. Exposure switch.
• D. Anode.

Answer: (C)

The key idea is beam restriction through collimation. The collimator uses adjustable lead shutters to define and shape the useful X-ray field so it matches the size and shape of the image receptor. This is essential for protecting the patient from unnecessary exposure and for reducing scatter to improve image quality. The exposure switch merely starts and times the exposure; it doesn’t shape the beam. The protective housing provides shielding to limit leakage radiation, and the anode is the target where electrons convert to X-rays—affecting energy and intensity, not the beam’s geometry. So the component that mainly controls how big and what shape the beam is is the collimator.