Law of unintended consequences

From the New York Times:

Britain was planning on using full body scanners at airports to enhance security after the Christmas Day bombing attempt in Michigan. Apparently, these scanners create an image of the body being scanned, which includes the genitals and any *ahem* enhancements.

Clearly, someone didn't think this through because now they will need to pass laws to exempt security personnel from child pornography laws. Britain also has some of the world's most aggressive paparazzi - images created of celebrities as they enter the country would be worth a fortune. I can see the US Weekly now: which of your favorite actresses really has fake boobs? See page 15!

I'm in favour of making our airports actually safer (take your shoes off? 30z of liquid? please...), but I'm not sure turning everyone into a porn star is a good solution. First, why are the images saved? Second, couldn't they be auto-analysed and then only exceptions reviewed manually?And third, do we have any evidence (say, in the form of controlled trials) that shows full body scanners catch more than metal detectors and pat downs?