Measurement of electron density and effective atomic number using dual-energy x-ray CT

Abstract

The information on the electron densities of bodies is important for the treatment planning of radiotherapy. In order to obtain the electron densities directly, we have developed dual-energy X-ray computed tomography (CT) using synchrotron radiation. It was experimentally proved that the electron density was deduced with about 1% accuracy from two linear attenuation coefficient. However, the linear attenuation coefficient were measured by a few percent lower than the theoretical ones. We assumed that the less accurate linear attenuation coefficients were caused by the influence of scattered radiation and the non-linearity in the response of the detector. In comparison of the scattered radiation to the simulation results, the scattered radiation contributed at the most 0.5% to the linear attenuation coefficients. Correcting the non-linearity in the detector response functions, the values of linear attenuation coefficient were improved drastically.