Design optimization of X-ray security scanner based on dual-energy transmission imaging with variable tube voltage

Abstract

At airports and ports, X-ray security scanners based on dual-energy transmission imaging have been operated to prevent importation of contraband articles including weapons, narcotics, and explosives. Security scanners currently operated by the Korea Customs Service use a fixed tube voltage (i.e., 160 kVp); hence, it has a limitation in detecting thinly-coated and/or low-density organic contraband articles. Tube voltage lower than 160 kVp affords an advantage in terms of enhanced contrast for organic materials, albeit at the cost of penetration power, and vice versa. Therefore, a security scanner with variable tube voltage that is adjustable according to the physical/chemical properties of the object to be inspected, has the potential to improve detection probability for contraband articles. In the present study, security scanner design optimization specifically in terms of the X-ray generator and the dual-energy detector was performed by Monte Carlo (MC) simulations. Then, the performance of the designed system was evaluated using a simple phantom to demonstrate the advantages of the variable tube voltage application. Additionally, the standard kits were used for performance evaluation in terms of simple penetration and wire display, which are the two parameters specified in Korean law.