| Yue Haizhen,Zhang Yibao,Hu Qiaoqiao,Liu Zhuolun,Jiang Fan,Gong Jian,Wu Hao.Absolute dose calibration and output factor simulation for flattened and flattening filter-free Monte Carlo model of 6 MV photon beams[J].Chinese Journal of Radiological Medicine and Protection,2017,37(1):29-34 |
| Absolute dose calibration and output factor simulation for flattened and flattening filter-free Monte Carlo model of 6 MV photon beams |
| Received:August 10, 2016 |
| DOI：10.3760/cma.j.issn.0254-5098.2017.01.006 |
| KeyWords:Flattened model Flattening-filter free model Monte carlo Output factor Absolute dose calibration |
| FundProject:国家自然科学基金（11505012）；北京市医院管理局“青苗”计划专项经费资助（QML20151004）；质检公益性行业科研专项（201510001-002） |
| Author Name | Affiliation | E-mail | | Yue Haizhen | Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Radiotherapy, Peking University Cancer Hospital & Institute, Beijing Cancer Hospital, Beijing 100142, China | | | Zhang Yibao | Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Radiotherapy, Peking University Cancer Hospital & Institute, Beijing Cancer Hospital, Beijing 100142, China | | | Hu Qiaoqiao | Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Radiotherapy, Peking University Cancer Hospital & Institute, Beijing Cancer Hospital, Beijing 100142, China | | | Liu Zhuolun | Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Radiotherapy, Peking University Cancer Hospital & Institute, Beijing Cancer Hospital, Beijing 100142, China | | | Jiang Fan | Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Radiotherapy, Peking University Cancer Hospital & Institute, Beijing Cancer Hospital, Beijing 100142, China | | | Gong Jian | Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Radiotherapy, Peking University Cancer Hospital & Institute, Beijing Cancer Hospital, Beijing 100142, China | | | Wu Hao | Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Radiotherapy, Peking University Cancer Hospital & Institute, Beijing Cancer Hospital, Beijing 100142, China | wuhao_bicr@sina.com |
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| Abstract:: |
| Objective To explore the Monte Carlo calculation methods for the absolute dose calibration and output factor of 6 MV flattening-filter (FF) and flattening-filter free (FFF) photon beams based on TrueBeam accelerator. Methods The BEAMnrc code was used to model the LINAC head of FF and FFF modes. The BEAM_up covers the components from the target to the monitor chamber, and BEAM_down includes the structures beneath the chamber, the dose deposit to the monitor chamber contributed by the incidence electrons and scattered particles from the secondary collimators were calculated respectively. The incidence electron-induced dose at certain depths on the central axis were simulated by means of the DOSXYZnrc code. By means of dose calibration equation, the calibration factor for the standard field (10 cm×10 cm) and the output factors for various fields (1 cm×1 cm-40 cm×40 cm) were computed respectively. Results For the 6 MV FF and FFF beams under the standard 10 cm×10 cm field, 1 MU equals to 7.747×1013±3.099×1011 and 3.248×1013±1.624×1011 electrons to the target, respectively, which deposited 21.53 and 35.01 cGy to the monitor chamber of the virtual accelerator respectively. The difference between the simulated and calculated output factors were 0.72%±1.4% and 0.56%±0.78% for FF and FFF, respectively. Conclusions The model generated and measured output factors agree well, indicating the good accuracy of the dose calculation by the model, which would provides basis for further clinical dosimetric studies. |
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