Two materials of different composition can have very similar grey values in an X-ray Computed Tomography (CT). This is because X-ray CT uses polychromatic sources in combination with energy-integrating detectors and the materials have a mass attenuation coefficient that is dependent on composition and photon energy. A distinction between different materials with similar grey values can be made by combining information from scans performed with different spectra, which can be achieved by varying the tube voltage and filtration. However, the polychromatic behaviour of laboratory based X-ray CT complicates the choice of the appropriate scanning conditions for such dual energy methods. Here, the programme Arion, for simulating realistic radiographic projections is used to determine optimal scanning parameters
