Patent ID: 6163591
Filing Date: 2000-12-19
Classification: G01V

Abstract:
Apparatus for screening an item to detect regions within said item having different opacity to radiation, said apparatus comprising:a conveyor system for carrying said item along a path; andan array of sensors, each sensor comprising a radiation source (SO1,SO2,SO3) and a radiation detector (SE1,SE2,SE3) disposed upon opposite sides of said path and serving to generate transmission signals indicative of opacity to radiation between said radiation source and said radiation detector in a plane intersecting said path, said sensors being disposed at a plurality of different locations along said path and being arranged to irradiate said item from a plurality of different angular orientations about said path; characterised bya signal processor for processing said transmission signals from said array of sensors to detect contours of maximum local rate of change in opacity within a plane through said item to generate cross section signals indicative any boundaries in said plane between said regions having different opacity to radiation and responsive to said cross section signals for a plurality of planes through a region to detect if said region matches one or more predetermined screening criteria.