Which statement about beam restriction is true?

• A. The exposed area should never be larger than the film size used.
• B. The useful beam should be limited to the smallest area practicable and consistent with the objectives of the radiographic examination.
• C. The x-ray beam area ratio should be less than one.
• D. The beam area is unrestricted.

Answer: (B)

Limiting the beam to the smallest area practicable is the essential idea here. By restricting the useful x-ray beam to only the part of the anatomy that needs to be imaged, you minimize radiation exposure to surrounding tissues and reduce scatter that would otherwise degrade image contrast. This not only protects the patient (ALARA) but also improves image quality, since less scattered radiation reaches the film or detector.

The best statement conveys this balance between diagnostic needs and protection: expose only the area required for the exam, as tightly as possible while still achieving the radiographic objective. The other points are more rigid or incorrect: a field larger than the film is inefficient and increases dose, and a beam area ratio less than one isn’t a universal rule used in practice. Saying the beam area is unrestricted directly contradicts the purpose of beam restriction.