I think this would be good to use along side the normal metal detectors, like if it goes off you walk through one of these so it doesn't take as long to show them where the metal is (I hate waiting). Even though there might be some privacy issues it is much better this way than having to strip down to show them IMO. I know that my grandad sets off the metal detectors with his knee because of his knee reconstruction an I'm sure he would prefer to do it this way than to go through all the other stupid rigmarole of the hand held metal detectors and that kind of thing.
I don't think this is pornographic at all unless you use a lot of imagination (but you might as well google instead
).