http://www.theregister.co.uk/2006/04/03/transport_police_mobile_xray/
John Lettice
"According to Image Scan, however, these are high energy units designed to check baggage, not suitable for use on people, while the devices used in the knife scan trials are conventional metal detectors. In this 'successful' trial, DfT intended to combat knife crime. Ten thousand people were scanned, 100 were arrested and 68 knives detected. As we understand it, arrests related to the knives detected were in the mid forties, but the offences for which the other arrests were made have not been specified. For a fixed scanner at an airport a hit rate of this order could be seen as a success of sorts (only of sorts, because finding that number of people trying to carry weapons on board would scare airport managers witless), but these are not fixed scanners."
