Preliminary results of a Multi-Energy CT system for small animals

A new multi-energy CT for small animals is being developed at the Physics Department of the University of Bologna, Italy. The system makes use of a set of quasi-monochromatic X-ray beams, with energy tunable in a range from 26 to 72 keV. These beams are produced by Bragg diffraction on a Highly Oriented Pyrolytic Graphite crystal. With quasi-monochromatic sources it is possible to perform multi-energy investigation in a more effective way, as compared with conventional X-ray tubes. Triple-energy projection allows to combine a set of three quasi-monochromatic images of an object, in order to obtain a corresponding set of three single-tissue images, which are the mass-thickness map (product of density and thickness) of three reference materials. The triple-energy technique can be applied to the mass-thickness-map reconstruction of a contrast medium, because it is able to remove completely the signal due to other tissues (i.e. the structural background noise). Here, we present a description of the system and the methods for combining the images at the different energies. We also show some results of images acquired at three different energies and of the reconstructed information about the contrast medium (Iodine). We achieved that the measurement of the Iodine mass-thickness agrees very well with the known concentration of the injected Iodine solution. © 2009 IOP Publishing Ltd and SISSA.