Lateral Migration Radiography Image Signatures for the Detection and Identification of Buried Land Mines

摘要

Lateral migration radiography (LMR), a new form of Compton backscatter x-ray imaging, is applied to the detection and identification of buried land mines. Uncollimated detectors provide images that are due primarily to single-scatter photons from the soil surface or near-surface. Collimated detectors provide images that are due primarily to multiple-scatter photons from the near-surface or sub-surface. Noise removal and image enhancement techniques including simple weighted filters, Weiner filters, optimal filters and neural networks have been successfully employed on LMR images. Information from both the uncollimated and collimated detector images is used to effectively remove surface clutter and enhance mine detection and identification. An innovative rotating collimator for the x-ray source has been developed to provide rapid side-to-side scanning of the source beam without having to move the x-ray generator in this direction. Acquisition of detailed images of a 40 cm by 40 cm area takes from 30 to 60 seconds, depending on desired resolution. The construction and testing of a portable LMR system for out door mine detection was completed. This system includes the x- ray generator; rotating source collimator; large area scintillator detectors; system frame assembly; motors and sensors for side-to-side and front-to-rear scanning; x-ray generator scan and data acquisition and processing systems; a standoff-to-vehicle IR modem communication system; and a portable electric generator power system. System weight (not including the vehicle) is about 160 kg, but this initial portable system was significantly over-designed; system weight for a prototype should be in the range of 100 kg. X-ray generator power requirement is from 200 to 800 watts. This portable system successfully acquired images of mines buried in an indoor soil box and then in out-of-door tests. Very good image results were obtained when the system was employed on the vehicular test lanes at Fort A.P. H7.