Originally Posted by
senseker
We have one wbi at sfo here, and I work with it every day at the checkpoint. Honestly, the images we see aren't that great, but good enough to determine if you have a wallet in your pocket or a knife strapped to your chest (and that's happened with me before). It's great technology, and it does work. There are signs next to it to explain what it does, and we have people explaining what it does as well. As a passenger, it is your right to not go through it. Anyone who opts out of the wbi instead gets a patdown. Nobody can force you to go through the wbi. It uses zero x-rays, so it's not going to expose you to anything. If I remember correctly, the machine that uses x-rays is the backscatter, a machine we don't use.
MMW or backscatter x-ray, neither detects explosives.
T-ray devices are no better at detecting explosives.