I was under the impression that all of the "x-ray" scanners aren't x-rays. Instead they are high frequency (100GHz+) back scattering machines.

The ones in the MKE air port are L3 ProVisions which fit the description I was aware of (http://www.sds.l-3com.com/products/mmwave.htm). No ionizing radiation means no "x-rays" etc.

I haven't been subjected to them yet, but before I walked into the airport I made my decision if I was going to be scanned or not.