CAMRT Radiography Practice Exam

What test is performed after changing the collimator light bulb?

1. Collimator light field alignment test

2. X-ray beam divergence test

3. Collimator light field/x-ray beam congruency test

4. Collimator performance evaluation test

The correct answer is: Collimator light field/x-ray beam congruency test

Changing the collimator light bulb can result in changes to the alignment or congruency between the light field and the actual x-ray beam. To ensure that the x-ray beam accurately corresponds to the light field projected by the collimator, a congruency test is essential. This test checks that the radiation field exactly matches the light field to avoid discrepancies that could affect imaging quality and patient safety. The congruency test typically involves projecting the light field onto a phantom or a calibrated grid, while simultaneously activating the x-ray beam. The areas exposed by the x-ray beam should match the illuminated area provided by the collimator light. Conducting this test after a collimator light bulb change is a critical quality assurance measure to confirm that imaging will remain accurate and adheres to safety standards. It’s particularly important in ensuring reproducibility and precision in radiographic procedures.