@misc{oai:repo.qst.go.jp:00067704,
 author = {Torikoshi, Masami and 取越 正己},
 month = {Jan},
 note = {Monochromatic x-ray CT at two different energies provides information about electron density (re) of human tissue without ambiguity due to the beam hardening effect. This information makes the treatment planning for heavy-ion radiotherapy more precise. We have started a feasibility study on the dual-energy x-ray CT by using synchrotron radiation. We developed a linear scanning CT system in order to clarify what precision in the measurement was achieved. The experiments were carried out using monochromatic x-rays of 40, 70 and 80 keV. Comparison of measured electron densities with the theoretical values proved that these values were in agreement in 0.9 % on average. We have constructed the dual-energy X-ray CT system with a two-dimensional scintillator array to take images in a short time. At present, it has been partially found that the 2D system measures the electron densities in the precision of about 1 %.Effective atomic numbers (Zeff) are obtained as well from the dual-energy x-ray CT. The tomographic image based on each of re and Zeff presents a different feature of a material, and its contrast differs from that in a conventional CT image. Both the images of a sample of kidney of a pig are shown for example. The left lower is the re image, and the right lower is that of Zeff. The renal pelvis is clearly distinguished from the renal medulla. Some dark spots in the left drawing, which are inferred to be blood vessels, are invisible in the right one. It tells that the spots consist of similar elements of the renal medulla while the electron densities are abnormally low. The feature of the images may help distinguish more clearly tissues or organs with aid of difference contrast from the conventional CT images., ポータブルシンクロトロン放射光とその応用に関する国際会議},
 title = {Development of Dual-Energy X-ray CT using Synchrotron Radiation},
 year = {2004}
}