Measurement of electron density distribution using heavy ion CT

Clinical trials for tumor treatment using highly energetic heavy ions are now in progress at the HIMAC. In order to achieve the radiotherapy more precisely, it is important to know the distribution of the electron density in a human body. For this purpose, we have developed a broad beam heavy ion CT system. The performance, especially the electron density resolution, of this system is estimated in this work. Some kinds of the solution targets with the known electron densities were used as samples. The projection data were obtained using 12C of 290 MeV/u, 20Ne of 400 MeV/u and 4He of 150 MeV/u. The experimental values were in good agreement with the calculated values.