Development of prototype backscatter X-ray security scanner for luggage inspection

In the Republic of Korea, for the purpose of security screening at ports and airports, the present system for inspecting small cargo/luggage relies on transmission X-ray imaging, with which discernment of organic and powder-form materials in images is difficult. Backscatter X-ray imaging techniques, contrastingly, are sensitive to organic materials (i.e., low-Z elements) due to a higher probability of Compton scattering relative to other photon interactions. Such techniques, therefore, have the potential to be used in security screening systems for the detection of organic compounds such as drugs and explosives. In the present study, a prototype backscatter X-ray security scanner for luggage screening was developed, and its performance was evaluated at various tube voltages. It was found that the isolation contrast, which indicates the minimum discernible thickness of a plastic panel when the background material of the image is steel, was approximately 1 mm at the tube voltage of 120 kVp. Moreover, amorphously shaped contraband articles randomly hidden inside the luggage were clearly visible at tube voltages ranging from 80 to 160 kVp. The developed backscatter X-ray security scanner is expected to provide improved detection efficiency for thin objects and/or illicit organic materials compared to a transmission-based X-ray imaging system.