David Schafer

Dual Energy Volumetric X-ray Tomographic Sensor for Luggage Screening

Various imaging sensors have been used for luggage screening for explosive detection. Recent developments in dual energy X-ray volumetric computed tomography (CT) have demonstrated its advantages over other imaging sensors for luggage screening. These advantages include higher performance in automatic explosive detection, effectiveness for weapon detection, superior visualization capabilities, and automatic visual cueing for on-screen threat resolution. In this paper, we describe the performance of one such X-ray sensor using our transportation security administration (TSA) certified dual energy volumetric CT for explosive detection.

Variable Pitch Reconstruction Using John's Equation

We present an algorithm to reconstruct helical cone beam computed tomography (CT) data acquired at variable pitch. The algorithm extracts a halfscan segment of projections using an extended version of the advanced single slice rebinning (ASSR) algorithm. ASSR rebins constant pitch cone beam data to fan beam projections that approximately lie on a plane that is tilted to optimally fit the source helix. For variable pitch, the error between the tilted plane chosen by ASSR and the source helix increases, resulting in increased image artifacts. To reduce the artifacts, we choose a reconstruction plane, which is tilted and shifted relative to the source trajectory. We then correct rebinned fan beam data using Johns equation to virtually move the source into the tilted and shifted reconstruction plane. Results obtained from simulated phantom images and scanner images demonstrate the applicability of the proposed algorithm.