Dual-Energy Computed Tomography (DECT) is known as a useful method to discriminate different objects with similar chemical properties. DECT measures the linear attenuation coefficient of the scanned object at two different x-ray energies. Using these two energy spectra, we can characterize the scanned objects by using the dependency of the linear attenuation coefficients on the x-ray energy and chemical characteristic of the material. Finding the optimum source spectrums for DECT method to attain the best material discrimination, is the aim of this study. Materials and Methods: The present study uses a simulation method to find the maximum differences between the HU values of the tissuesat 80 and 140 kvp which have the same attenuation properties, such as soft tissue, muscle, lung, and bone. IMASIM software is used to simulate different source spectrums by using of the different filters, such as aluminum, tin and copper, to produce the phantom images. The HU values of different tissues at different energies, are then measured and compared quantitatively. Results: The results show that the maximum differences between the HU values, pertain to cortical bone, for 80 and 140kvp when 2mm copper plus 0.4mm tin is used (45%). It has to be noted that the minimum differences (36%) between the HU values occur for cortical bone at 80 and 140 kvp and are recorded when the simulated source spectrums were made by 3mm Al plus 0.4mm tin filters. Conclusion: The results of this study demonstrate that the highest material discrimination may occur at 80 and 140kVp when 2mm Copper plus 0.4 mm tin filters are used as the added filters in front of the x-ray source with 140kVp.
