Multi-energy, Limited View Computed Tomography (CT)
Current X-ray imaging methods for scanning luggage are based solely on X-ray attenuation, a process dependent on both the absorption and scattering of X-rays by the material under investigation. For most all fielded X-ray systems, scattered photons are ignored.
The goal of this project is to explore the utility of these scattered photons in terms of improvements they may offer to the characterization of materials within luggage. The effort is motivated by recent interest at DHS in X-ray systems comprised of spatially fixed sources and detectors in contrast to traditional computed tomography (CT) systems where source/detector arrays rotate around the items being scanned.
The limited number of source-detector paths compared to the full-scale CT case creates substantial challenges for image formation and, ultimately, target detection. Using energy resolving detectors in these systems to collect scattered photons significantly increases the number of “looks” we have at the scene even in these fixed geometries, potentially allowing us to greatly enhance the information content provided by these systems.
The focus of this project is on realizing this potential by addressing two, fundamental challenges. First, the development of a computational model linking the observed data to the material properties and second, the development and validation of processing methods based on this model for using scattered photons in addition to traditional attenuation data to form images.
The most immediate value of the research in this project to the DHS Enterprise lies in the potential of these models and processing methods to improve the accuracy of screening checked baggage, as well as luggage inspected at the checkpoint.Year 4 Annual Report