When should geometric variation on a dose calibrator be performed?

Geometric variation on a dose calibrator should be performed at installation and yearly to ensure accuracy in radioactivity measurements. This procedure is essential because it tests how the geometry of the source being measured affects the dose calibrator's readings.

When a dose calibrator is first installed, geometric variation assessments help confirm that the device is functioning correctly in its operational environment and that it provides accurate measurements for different radionuclides. The yearly assessments are crucial for maintaining ongoing quality control. Over time, factors like mechanical changes, wear and tear, or environmental influences can affect the calibrator's accuracy. Performing this check annually helps identify and rectify any discrepancies that may arise, ensuring that the measurements remain reliable for patient safety and treatment efficacy.

Daily, quarterly, or hourly checks do not provide the necessary comprehensive oversight needed for a dose calibrator's geometric accuracy. Those intervals might be suitable for other aspects of routine quality control, but they are insufficient for the geometric variation assessment specifically.