| 摘要 |
A scanning unit (10) for identifying contraband, such as guns, explosives and illegal drugs, within objects, such as cargo containers and luggage, moving through the unit along a first path comprises at least one source (16) of a beam of radiation movable across a second path that is transverse to the first path and extends partially around the first path. A stationary detector (20) transverse to the first path also extends partially around the first path, positioned to detect radiation transmitted through the object during scanning. In one example, a plurality of movable X-ray sources (16a-16t), each transmitting a cone beam of radiation, are supported by a semi-circular rail (18) perpendicular to the first path. In this example, the detector, which may be a detector array comprising a plurality of two dimensional detectors, is also semi-circular and perpendicular to the path. A fan beam may also be used. Radiographic images may be obtained and/or computed tomography ("CT") images may be reconstructed. The images may be analyzed for contraband. Energy sensitive detectors (60) may also be provided. The radiation sources may emit radiation of different energy distributions or each source may selectively emit radiation of different energy distributions. Data derived from a voxel of the object at the different energy distributions may be processed to determine the material content of the voxel. Images based on that data can be fused with the radiographic or CT images to facilitate identification of contraband based on size, shape and material content of regions within the object. Methods of scanning objects are also disclosed. |
