Abstract: Single energy computed tomography (CT) scanners use measurements of
densities to detect explosives in luggage. It is desirable to apply dual energy
techniques to these CT scanners to obtain atomic number measurements to reduce
false alarm rates. However, the direct application of existing dual energy
techniques has practical problems, such as, approximation errors and lack of
boundary constraints in dual energy decomposition, image artifacts, and x-ray
spectral drifts. In this paper, we present methods to reduce these problems.
The methods include constrained dual energy decomposition, adaptive scatter
correction, nonlinear filtering of decomposed projections, and real-time
image-based correction for x-ray spectral drifts. We demonstrate the
effectiveness of the methods using simulated data and real data obtained from a
commercial dual energy CT scanner.
