Quantitative Material Reconstruction in CT with Spectroscopic X-ray Pixel Detectors -- a Simulation Study

Modern photon counting X-ray detectors offer energy resolving capabilities for every single photon interacting in the sensor layer. This provides a new dimension of information which could and should be used to improve image quality. As the energy dependance of X-ray attenuation is a characteristic for the material, one can gain information on the composition of the object by analysis of the attenuation as a function of energy. One possibility is the material reconstruction, where the areal densities of chosen basis materials are obtained in projective geometry. For instance, this method could be used not only to distinguish and identify contrast agent from other highly absorbing regions, but also to gain quantitative information on the specific material. We have successfully applied this technique to computed tomography with Monte-Carlo simulated data and investigated the properties of this approach. Material selective images are presented and image quality properties are evaluated. The Signal Difference to Noise Ratio (SDNR) in the material-reconstructed and in the conventional CT images are compared.