When should geometric variation on a dose calibrator be performed?

Geometric variation on a dose calibrator refers to the assessment of the calibrator's accuracy across different geometries of container or syringe where the radioactive material is housed. Performing geometric variation is essential to ensure that measurements remain accurate despite changes in geometry that can affect the attenuation of radiation.

The correct timing for conducting geometric variation is at installation and after repair. When a dose calibrator is first installed, it needs to be verified to ensure that it provides accurate readings across the various geometrical configurations that may be encountered during routine use. Similarly, after any repair, the functionality and accuracy of the device could be impacted. Thus, it's crucial to perform this test to confirm that the device is properly calibrated and functioning correctly in its new or repaired state.

Conducting this variation test only before calibration or after daily use does not ensure comprehensive verification of the device's performance. Regular weekly checks may maintain operational standards but do not replace the need for specific assessments after installation or repair. Therefore, testing at these critical points ensures the highest accuracy and reliability in dose measurements, which is essential in nuclear medicine for patient safety and effective treatment.