Effectiveness of a combination of ML-EM and STIM-CT in PIXE-CT for biological specimens

Sato, Takahiro; Koka, Masashi; Kozai, Naofumi   ; Shimizu, Yasuo*; Dobashi, Kunio*; Kada, Wataru; Yokoyama, Akihito; Okubo, Takeru; Yamazaki, Akiyoshi; Ishii, Yasuyuki; Kamiya, Tomihiro

In the ML-EM for PIXE-CT, energy loss of incident particles and absorption of X-rays affect must be estimated using STIM-CT. This paper shows the appropriateness and the expected spatial resolution of this method are evaluated by a computer simulation and some practical experiments using 3 MeV proton microbeam with a diameter of 1m at TIARA. The PIXE-CT experiments were carried out using a dried unicellulate and human lung tissue as a test sample placed on an automatic rotation stage, which made a full turn by rotating 360 at each step of 18 in vacuum. In the simulation, X-ray yield and absorption were calculated using density distribution of two-dimensional Shepp phantom. The results of those simulation and experiments have proved that this method is effective in PIXE-CT.