| Summary: | 碩士 === 長庚大學 === 醫學影像暨放射科學系 === 104 === The purpose of this study is to develop a tetrahedral phantom and its Monte Carlo simulation. Although voxel phantoms are widely used in Monte Carlo simulation of dose calculation, they have several limitations. First, they have partial volume effect. Second, it is difficult to model very thin structures owning to the finite voxel resolution. Third, the voxel phantoms cannot be deformed. Polygonal mesh phantoms can overcome these limitations, however, they cost longer time in simulation and they cannot account for tissue heterogeneity. Tetrahedral phantoms have both advantages of the above phantoms, which are deformable, more efficient and can deal with spatial and temporal heterogeneous. This study was divided into two parts. First, we have developed a tetrahedral phantom and applied it to Monte Carlo simulation; in this part, in-house codes were developed to reduce several large volume tetrahedron inside the tetrahedral phantom and to account for tissue heterogeneity. Secondly, we have analyzed the simulation results to DVHs, dose distribution, depth doses and dose profiles. These results showed that we have already developed this phantom and it can be implemented in Geant4 Monte Carlo for dose calculation.
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