An Ultrasonic Approach for Sensing and Imaging Shielding Containers of Nuclear Threats

A new guided wave imaging application for fast, low-cost ultrasound-based cargo scanning system is presented. The goal is the detection of high-atomic-number, shielding containers used to diminish the radiological signature of nuclear threats. This ultrasonic technology complements currently deployed X-ray-based radiographic systems, thus enhancing the probability of detecting nuclear threats. An array of acoustic transceivers can be attached to the metallic structure of the truck to create a guided acoustic wave. Guided medium thickness and composition variation creates reflections whose placement can be revealed by means of an imaging algorithm. The knowledge of the reflection position provides information about the shielding container location inside the truck. Reflected waves in the guided domain bounds may limit the performance of imaging methods for guided media. This contribution proposes a solution based on Fourier domain analysis, where plane wave components can be filtered out, thus removing non-desired contributions from bounds. Apart from this, the imaging algorithm can be used to recover information about material composition. Simulation-based examples are used for algorithm validation.