What is the purpose of maintaining collimation during radiography?

• A. To limit the radiation field, reduce patient dose, and improve image quality.
• B. To expand the image field for more anatomy.
• C. To increase exposure time.
• D. To enhance contrast with added shielding.

Answer: (A)

Collimation confines the x-ray beam to the area of interest. By limiting the field, fewer tissues are irradiated, which lowers the patient dose. It also reduces the amount of scattered radiation produced inside the body and reaching the image receptor, which decreases image fog and improves contrast and detail in the final image. Expanding the field would raise patient dose and scatter, increasing fog; extending exposure time would raise dose without improving the image; and shielding is used to protect tissues and is not the mechanism by which collimation enhances the image.