X-ray Lateral Migration Radiography System for the Application of Land Mine Detection

摘要

X-ray lateral migration radiography (a Compton backscatter imaging method) generate images of land mines and other objects buried with less than 10 cm of overlaying soil. An x-ray pencil beam illuminates the object area pixel-by-pixel, and a detector array of two uncollimated and two collimated, large area, scintillators respectively register once-scattered and multiple-scattered photons from mines, other buried objects, and the soil background. Two surface-feature-dominant uncollimated detector images and two subsurface-feature-dominant collimated detector images are typically generated. In the collimated detector images, a shifting of the images from the object center is propotional to the depth-of-burial of the detected object. Real mine tests have been conducted and the images show the included air volume as a prominent feature. The combination of the geometrically regular air volumes and mine case present unique features which distinguish mine from nonmine objects. In fact, identification of some land mine types can be achieved from the acquired images. A field-test version of the system, to be used as a land mine object confirmation/identification detector is under construction. The completed generator/collimator x-ray source has been employed to produce the system-design raster direction of the incident photon beam, whilst one-dimensional movement of the object is temporarily employed to simulate the orthogonal image axis. Easily recognized acquired images of the test object clearly indicate that the desired pixel dwell time of 0.01 sec has been achieved. This image acquisition speed translates into approximate values of 1.8 sec for a 20 by 20 cm interrogated area, consistent with scanning an antipersonnel mine, and 16 sec for a 60 by 60 cm area, consistent with an antitank mine.