Dual Energy CT in Clinical Practice, Medical Radiology. Springer-Verlag Berlin Heidelberg

Abstract

Dual-energy CT enables improvement of material and possibly tissue separation when compared to regular CT. Philips Healthcare has been successfully operating a dual-layer detector system in a modified Brilliance 64 CT scanner installed since 2005 in Hadassah University Medical Center, Israel. The dual-layer detector acquires single x-ray source CT data using two scintillation layers on top of each other with which two energy datasets are acquired simultaneously. The results of the two reconstructions are mapped into a plane created from the Hounsfield units (HU) of the upper-layer image versus the HU of the lower-layer image. We find that different materials end up in different definable regions in the HU-plane, so material separation can be performed. Application of a special correction on the reconstructed images achieves stability on the HU-plane despite beam-hardening effects on this image-based dual energy CT. We describe the material separation capabilities and algorithms with such a configuration and conclude that the combination of the dual-layer CT with the classification analysis in the HU-plane is a practical and robust method that may improve clinical applications, in particular those involving Iodine-Calcium.