A system and a method for determining the density of an object. The intensity of x-rays backscattered from the object is measured by at least two backscatter detectors disposed at different distances from the intersection of an incident x-ray beam with the plane of the detectors. At least one of detectors...http://www.google.fr/patents/US6320933?utm_source=gb-gplus-shareBrevet US6320933 - Multiple scatter system for threat identification
