Security X-ray Screening with Modulated-Energy Pulses

This paper provides a brief overview of new screening methods that employ Modulated-Energy X-ray Pulses (MEXP) to provide a number of near-simultaneous multi-energy measurements in transmission-, backscatter-, and Computed Tomography (CT) security systems. In transmission X-ray cargo screening, these multi-energy measurements improve material discrimination, maximize penetration, and enhance contrast resolution while simultaneously reducing inspection time and dose to the environment, thus resulting in a smaller exclusion zone. In backscatter systems, the use of this method will increase penetration and improve image quality of concealed objects located deeper below the surface. Specifically, different depths within an object can be probed simultaneously. In CT, our MEXP approach mitigates the main disadvantages of the conventional dual-energy technique: a) distortion of image of the boundaries between regions with large difference in density; b) limited range of object thickness where material decomposition is valid; c) ambiguity and artifacts caused by sampling different regions due to motion of the object between interlaced pulses with distinct energies. Results of testing of the prototype of high speed Adaptive, Multi-Energy Cargo Inspection System (AMEXIS) will be presented. Progress in the development of MEXP-based backscatter inspection system, and systems for cargo screening with Adaptive CT will also be shown.