A pencil beam of X-rays is scanned over the surface of the body of a person being examined. X-rays that are scattered or reflected from the subject's body are detected by a detector. The signal produced by this scattered X-ray detector in then used to modulate an image display device to produce an image...http://www.google.com/patents/US5181234?utm_source=gb-gplus-sharePatent US5181234 - X-ray backscatter detection system
