Which QA test verifies the alignment between the radiographic field and the light field?

Which QA test verifies the alignment between the radiographic field and the light field?

• A. SID indicator
• B. Central ray indicator
• C. Light field accuracy
• D. Exposure rate accuracy

Answer: (C)

The field alignment is tested by checking light field accuracy. The light field is the visible representation produced by the collimator to guide where the x-ray beam will go. Verifying light field accuracy means confirming that the edges of the light field line up precisely with the actual x-ray field. If there’s any shift or mismatch, parts of the patient could be irradiated outside the intended area or critical anatomy could be underexposed, compromising both safety and image quality. The other QA checks are about different aspects: the SID indicator confirms distance is shown correctly, the central ray indicator ensures the beam is aimed at the intended center, and exposure rate accuracy measures the dose output, not the geometric alignment between light and radiation fields.

The field alignment is tested by checking light field accuracy. The light field is the visible representation produced by the collimator to guide where the x-ray beam will go. Verifying light field accuracy means confirming that the edges of the light field line up precisely with the actual x-ray field. If there’s any shift or mismatch, parts of the patient could be irradiated outside the intended area or critical anatomy could be underexposed, compromising both safety and image quality. The other QA checks are about different aspects: the SID indicator confirms distance is shown correctly, the central ray indicator ensures the beam is aimed at the intended center, and exposure rate accuracy measures the dose output, not the geometric alignment between light and radiation fields.