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直線加速器動態楔形濾器之蒙地卡羅模擬
Monte Carlo Simulation of Dynamic Wedges of LINAC
摘要
本研究希望透過蒙地卡羅程式BEAMnrc，模擬直線加速器（Varian21 EX, 6MV photon）在使用動態楔形濾器（dynamic wedges, DWs）時，各種照野與角度下之劑量分布，並與測量結果作比對驗證。由於治療乳癌常常會使用（DWs）技術，因此也將針對使用DWs放射治療時入射表面劑量作模擬與探討。結果顯示，在劑量剖面（dose profile）比對發現，除了小照野外，蒙地卡羅模擬值與TPS以及量測值有很好的一致性。在百分深度劑量（PDD）方面，蒙地卡羅模擬值與實驗值以及測量值在增建區之後有很好的吻合度。然而，在入射表面劑量部分，TPS值有明顯高估的現象。在深度5 mm之後，TPS可如蒙地卡羅模擬一樣地準確預測劑量。
並列摘要
The aim of this study was to simulate the LINAC with dynamic wedges (DWs) using Monte Carlo simulation (MC). The dose distributions of various field sizes and wedge angles were compared between MC and the measurements. Due to the DWs are often utilized under breast cancer, the entrance surface doses of patients under LINAC with various DWs were simulated and discussed. Except the small field size (5x5 cm^2), the dose profiles of Monte Carlo simulation were in good agreements with the measurements and treatment planning system (TPS) calculations. Beyond the build-up regions, the PDDs of MC, TPS and measurement also showed good agreements. However, the entrance surface doses calculated by TPS have been found to be overestimated significantly. After the 5 mm depth, TPS will give accurate PDDs as those of Monte Carlo simulations.
延伸閱讀
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- 黃瑞京、簡聿皇、張國平（2013）。蒙地卡羅方法模擬瓦利安直線加速器楔形濾器下射束特性研究。慈濟技術學院學報，(21)，73-87。https://www.airitilibrary.com/Article/Detail?DocID=16818814-201309-201311180023-201311180023-73-87
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