Model 951 | Is there any way to permanently set the sensitivity higher or lower to adjust for constant changes in background levels (around an X-Ray machine, etc) ?

The nukeALERT contains an Adjustment Switch that allows you to manually adjust the lowest level sensitivity of the detector.  This should not be casually adjusted since it reduces the highest sensitivity of the detector.  Usually, this switch is adjusted at the factory or by our tech support team. It is important to track your minimum settings so you don't end up with 50 nukeALERT’s, each with different sensitivity settings.