Optimization of parameters in LINAC Monte Carlo simulations

• Main Authors: Sum, Ming-Ning, 孫泯寧
• Other Authors: Chang, Kwo-Ping
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/bkfz95

碩士 === 慈濟技術學院 === 放射醫學科學研究所 === 103 === Abstract Monte Carlo method, which is identified as an accurate approach in many studies, has been applied extensively in the dose simulation of radiotherapy fields. The commissioning of LINAC(linear accelerator) Monte Carlo needs to establish the geometry of LINAC and the information of the incident electrons. Determination of these initial parameter is an important issue. Varian 21 EX LINAC (6 MV, 10 MV) has been simulated by BEAMnrc codes in the present study. PDD (percentage depth dose) and dose profiles were calculated under various field sizes. The dose distributions of various energy and FWHM (full width at half of maximum) were compared with those of measurement, as the optimal values of energy and FWHM were determined. We also tried to find the optimal conditions of variance reduction techniques in order that we can reduce the simulation time without losing accuracy. According to the results, a standard procedure will be proposed for users who hope to derive the optimal initial parameters in LINAC Monte Carlo simulation.