Dual-energy decomposition using a kinestatic charge detector

The Kinestatic Charge Detector (KCD) is an electronic digital strip beam x-ray detector which has been shown to possess a high detective quantum efficiency, good spatial resolution, and good scatter rejection. We have investigated its use as a dual-energy x-ray detector detector, which involves the acquisition of two images with different mean x-ray energies that can be reconstructed using a suitable algorithm to form images of two basis materials such as bone and soft tissue. Dual-energy imaging with a single exposure may be performed with a KCD by segmenting its x-ray collection region into front and back regions. The lower x-ray photons will then be preferentially absorbed in the front region. Computer simulations were performed to evaluate a segmented KCD's ability to reconstruct various combinations of Plexiglas and aluminum. Actual experimental data were also taken for various Plexiglas and aluminum combinations with a non-imaging research KCD. The suitability of using analytic calibration functions as decomposition algorithms for aluminum and Plexiglas basis material images was investigated. Fits were performed for the computer simulations using the high-energy and low-energy data, with and without the addition of noise. Similar fitting techniques were used with the experimental KCD data. A true rms accuracy of 150 micrometer for aluminum and 500 micrometer for Plexiglas was obtainable from fits for the computer simulated data, even with the addition of noise. The experimental data taken with the non-imaging KCD yielded rms errors of approximately 250 micrometer for aluminum and 1000 micrometer for Plexiglas, comparable to simulated noisy data. We conclude that suitable decomposition algorithms exist for a segmented dual-energy KCD to be able to reconstruct aluminum and Plexiglas material thicknesses to an accuracy sufficient for clinical diagnosis in chest radiography.