Enhanced color coding scheme for kinetic depth effect X-ray (KDEX) imaging

Dual-energy X-ray imaging is a well-established technique to color code X-ray images of travelers' luggage with materials discrimination information. Existing dual-energy X-ray technologies are capable of calculating the effective atomic number of objects with high accuracy. However, dual-energy analysis alone is unable to isolate innocuous organic objects from threat objects as their correct classification is also determined by density. The lack of depth information, which is necessary to compute density, in X-ray images produced by standard 2D scanners has demanded the utility afforded by 3D technology. This paper reports the exploitation of the additional volumetric information afforded by the KDEX technique to supplement the dual-energy X-ray attenuation information resulting in improved specificity. The proposed formulate is able to discriminate between a wide range of materials as a function of Z and ρ. Together with laminographic data, an encouraging accuracy of Z and ρ up to 97% and 95%, respectively is obtained for well-defined homogeneous objects. A new color scheme is developed for color coding the derived ρZ information to highlight the presence of potential threat materials in the resultant 3D imagery. We wish to thank the UK EPSRC for funding this program of research.