Lateral Migration Radiography

Abstract

Lateral migration radiography (LMR) is a new form of Compton backscatter imaging (CBI) that utilizes both multiple-scatter and single-scatter photons. The LMR imaging modality uses two pairs of detectors. Each set has a detector that is uncollimated to predominantly image single-scatter photons and the other collimated to image predominantly multiple-scattered photons. This allows generation of two separate images, one containing primarily surface features and the other containing primarily subsurface features. These two images make LMR useful for imaging and identifying objects to a depth of several X-ray photon mean free paths even in the presence of unknown surface clutter or surface imperfections.The principles of LMR are demonstrated through Monte Carlo simulation of the photon transport. The Monte Carlo simulation results are verified with experimental measurements from an LMR system used for landmine detection. The presented research demonstrates the methodology for designing an LMR system, identifies methods for restoring and enhancing LMR images, and lays the foundation for the development of other applications of LMR, including, for example, the nondestructive examination of welds, castings, and composites.