A multi-energy X-ray backscatter system for explosives detection

Most luggage inspection systems are based on X-ray transmission technologies, such as radiography and computed tomography. These techniques have limitations, especially with large or dense objects or objects which are placed close to a wall not allowing access to the rear side for radiography (for instance with abandoned luggage). Portable systems using backscattered X-rays could be an alternative solution when analyzing a suspicious object from one side only, without contact, particularly for homeland security applications. However, portable systems are not currently available. X-ray backscatter imaging, unlike X-ray radiography, reveals low Z materials such as explosives, which may be hidden inside luggage or behind a screen. Specific analysis of backscattered spectra can provide further information about the suspect material in the backscatter image. This can help discriminate between explosive and inert materials. In this article, we detail this discrimination process and the associated developed laboratory prototype. Experimental results are presented, demonstrating the system's performance.