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Satoh, Daiki
no journal, ,
We report on the development of computational human phantoms and their application to dose calculation using radiation-transport codes. The latest computational human phantoms employ a three-dimensional mesh format, which can precisely reproduce not only large organs but also small regions, such as the lens of the eyes and the basal cell layer of the skin. Using this mesh format, the International Commission on Radiological Protection (ICRP) has developed reference computational phantoms for public (newborn, 1, 5, 10, 15 years old, and adult male and female), and JAEA has developed reference ones for Japanese. The radiation-transport codes can perform various analyses such as calculation of organ doses and radiation fields in the body by reading the computational phantoms. We introduce major radiation-transport codes used for dose calculations, and show some calculation results obtained using PHITS code developed by JAEA.
Ishikawa, Akihisa*; Koba, Yusuke*; Furuta, Takuya; Chang, W.*; Hashimoto, Shintaro; Yonai, Shunsuke*; Matsumoto, Shinnosuke*; Sato, Tatsuhiko
no journal, ,
There found to be a relationship between the dose-averaged linear energy transfer LETd and local tumor control in carbon-ion radiotherapy (CIRT). However, only physical dose and biological dose are registered in the past treatment records of CIRT in QST hospital and LETd can not be deduced directly. There is a method to estimate LETd based on RBE-LETd-fitted function but some problems such as non-singularity at the end point of carbon ions are known. On the other hand, we propose a method to reproduce the CIRT by reconstructing the beam transport geometry based on the treatment planning data and conduct Monte Carlo simulation. The LETd can be also computed directly. We therefore compared LETd obtained by Monte Carlo simulation with estimated LETd using the treatment planning data. We found that underestimation around the end point of carbon ions but the influence was local and thus the LETd estimates are valid for the purpose computing in organ scale.