Bum handheld scanners then
On a saner note. The hand held scanners used at a platinum refinery I worked at, would always go off if female staff had a copper containing IUD fitted (<1g Cu) ; from both belly and bum side scanning. This was 15 years back so the scanners used by the canuks must be pretty crappy not to pick up an ounce of gold.
(Alien as they are probe a lot)