The tomography beamline at the National Synchrotron Light Source

We compared the image contrast of a monochromatic CT, Multiple Energy Computed Tomography (MECT), being developed at the National Synchrotron Light Source for imaging the human head and neck, and a conventional CT scanner using phantoms. The same phantom images were also produced by computer simulations. The experimental results indicate that monochromatic CT, with a beam energy tuned just above the iodine K-edge, has ≃ 3-fold advantage in iodine image contrast over conventional CT with a 120 kVp beam. Modeling the same polychromatic beam and a monochromatic beam of the same mean energy at the same 3-rad close and 3-mm slice height on an 18-cm-diameter acrylic phantom, the simulations show a noise of 1.4 HU for MECT and 1.9 HU for CCT. Furthermore, despite the Cupping-effect corrections the bone contrast is lower in CCT and varies by 16 HU moving from the phantom's center to the edge; this indicates an advantage for MECT in detecting and quantifying lesions differing from surrounding tissue by their effective mean atomic number.