Features of dual-energy X-ray computed tomography

We proposed dual-energy X-ray CT for direct measurement of electron densities to make treatment planning for heavy ion radiotherapy more accurate. The accuracy was proved to be about 1% using synchrotron radiation in previous experiments carried out at SPring-8 and PF-AR. The electron densities of some porcine organs were measured in this method at SPring-8, and compared with data of ICRU Report. Besides, the atomic number of the object is also obtained as a byproduct. Comparing the CT-number given in conventional CT scanning is an important information. Images of the electron density and atomic number may give new information to medical diagnosis.