SPLIT-FILTER COMPUTED TOMOGRAPHY (CT) FOR ROUTINE DUAL ENERGY SCANNING

Abstract

Split-filter CT is a simple technique for obtaining dual energy CT images after a single 360° x-ray source rotation. The method consists of creating low and high energy spectra from a single source fan by filtering the two halves of the fan differently. From a practical standpoint, the acquisition of high quality split-filter images from a commercial scanner is dependent upon proper source, detector and split-filter alignment as well as on proper spectral calibration. These problems are discussed and split-filter images corrected for alignment and calibration artefacts are shown. The noise performance of any dual energy scheme is related to the quality of spectral separation between low and high energy beams and to the efficiency of dose utilization. The theoretical noise performance of the split-filter method is compared to other dual energy techniques, namely the dual-kVp method, using a generalized dual energy noise analysis. Results of split-filter scans from a clinical scanner are presented to demonstrate the ease of obtaining Compton and photoelectric images and exact spectral artefact correction at arbitrary monoenergetic energies on a routine basis. Split-filter images resulting from subtraction of low and high energy measurements are also shown to illustrate enhanced visualization of iodine contrast.© (1981) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.