Computed tomography for iodine contrast media detection using energy information measured by a current-mode detector

To exploit the energy information of X-rays in computed tomography (CT), we developed a current-mode detector that gave the energy distribution of incident X-rays. The CT value obtained for a given material in a phantom depended on the X-ray path length through the phantom. To ensure a constant CT value for a given material, we prepared response functions as a function of X-ray path length and applied these response functions in the unfolding process. When using response functions that depended on X-ray path length, the CT values obtained were constant for a given material. In addition, the CT values obtained for iodine contrast media were greater than the values obtained using conventional current CT, especially for higher X-ray tube voltages.