Increased tissue differentiation using color display of multiple-energy CT scans.
Just as the average value of the attenuation coefficient can be represented by the brightness of the pixel, the energy structure of the attenuation coefficient determines its hue. This can be measured by filtering the x-ray beam with W, Pb, and Sn at 100, 120, adn 140 kVp, respectively. The color differences seen in (a) CT images of phantom materials such as iodine and calcium, (b) brain specimens containing hemorrhage, meningioma, glioblastoma, or metastases, and (c) preliminary in vivo head and body scans represent variations in chemical composition across the tissue section. Measurements show that energy-selective filtration increases the separation between effective energies while reducing the dose for the same number of transmitted x rays.