In semi-annual testing for collimator light field and X-ray field alignment, which statements are true?

• A. 1 and 2
• B. 1, 2, 3
• C. 1 and 3
• D. 2 and 3

Answer: (B)

Light field alignment with the X-ray field is all about making sure the visible boundary you see with the light actually matches the area that will be exposed by the X-ray beam. This is crucial so that the anatomy you intend to image is captured correctly and the dose is confined to the intended region.

In semi-annual checks, you verify that the light field and the X-ray field coincide in size and position at the image receptor, and you do this across representative field sizes and collimator positions to catch any translational or rotational drift. You also compare the fields against a defined tolerance, so any misalignment is detected and corrected before clinical use. Because these elements—field congruence, consistency across field sizes/orientations, and adherence to tight tolerances—are all part of a proper collimation QA, all the statements describing these aspects are true.