I fail to see how you could possibly fit a (what looks to be) backscatter X-ray machine into a phone case like that, let alone do it in such a way that the person using it day-in day-out doesn't get cancer.<p>Furthermore the article states it'll use audio waves, not X-ray. At best that'll allow you to detect acoustically reflective objects from close range, not guns specifically, and not explosives at all.