How often should Light & X-ray Field Alignment be checked?

• A. Monthly
• B. Quarterly
• C. Semi-annually
• D. Annually

Answer: (C)

Maintaining that the light field matches the actual x-ray field is essential for accurate localization and dose delivery. The light field is used as a visual guide to shape and position the patient, so any mismatch with the radiation field could lead to irradiating the wrong area or missing part of the intended treatment, with safety and dose accuracy implications.

The semi-annual interval is a practical balance: the alignment tends to stay stable for months, so checking twice a year catches gradual drifts without overburdening daily workflow. If any service, recalibration, or noticeable change occurs, recheck promptly and adjust. More frequent checks would be more conservative but add workload, while waiting longer than six months increases the risk of undetected drift.