Optimization of a dual-energy imaging Kinestatic Charge Detector for chest radiography

The Kinestatic Charge Detector (KCD) technique of projection radiography shows promise when used for dual- energy imaging, which may be performed either by taking two separate exposures at different kVp settings (the dual-kVp method) or by taking a single exposure with the KCD segmented into a front and back region (the split-detector method), as the higher energy photons will be preferentially absorbed in the back region. Using computer simulations, we have optimized the dual-energy performance of a segmented KCD using the split-detector method for chest radiography. Theoretical optimization of imaging parameters and determination of contrast resolution were performed by minimizing pixel variances of the basis materials. The expected contrast resolution of the aluminum and plexiglas basis material images was found to be acceptable for purposes of clinical diagnosis. A detector medium of krypton produced better results than xenon at the same density, and the optimal kVp setting was in the range of 120-150 kVp. Preliminary dual-energy images were taken with a small field-of-view split-detector imaging KCD system. The experimentally obtained aluminum and plexiglas basis material pixel variances agree with the theoretical results.