| Li Zhengxian,Zhao Jingjing,Wang Meijiao,Zhou Li,Liu Dong,Wang Bosheng,Zong Shaofei,Ma Jingchao,Zhang Yibao.Modeling the correlations between radiation dose and scanning parameters of XVI cone beam CT[J].Chinese Journal of Radiological Medicine and Protection,2017,37(8):618-622 |
| Modeling the correlations between radiation dose and scanning parameters of XVI cone beam CT |
| Received:February 07, 2017 |
| DOI：10.3760/cma.j.issn.0254-5098.2017.08.012 |
| KeyWords:Cone beam CT Elekta XVI Radiation dose Radiological protection Image guided radiotherapy |
| FundProject:国家自然科学基金（11505012）；北京市自然科学基金（7172048，1174016）；北京市医院管理局"青苗"计划专项经费（QML20151004）；质检公益性行业科研专项（201510001-02） |
| Author Name | Affiliation | E-mail | | Li Zhengxian | Department of Radiation Oncology, Gongzhuling Guowen Hospital, Gongzhuling 136100, China | | | Zhao Jingjing | Department of Radiation Oncology, Gongzhuling Guowen Hospital, Gongzhuling 136100, China | | | Wang Meijiao | Key Laboratory of Carcinogenesis and Translational Research(Ministry of Education/Beijing), Department of Radiation Oncology, Peking University Cancer Hospital & Institute, Beijing 100142, China | | | Zhou Li | Division of Radiation Physics, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu 610041, China | | | Liu Dong | Department of Radiation Oncology, Gongzhuling Guowen Hospital, Gongzhuling 136100, China | | | Wang Bosheng | Department of Radiation Oncology, Gongzhuling Guowen Hospital, Gongzhuling 136100, China | | | Zong Shaofei | Department of Radiation Oncology, Gongzhuling Guowen Hospital, Gongzhuling 136100, China | | | Ma Jingchao | Department of Radiation Oncology, Gongzhuling Guowen Hospital, Gongzhuling 136100, China | | | Zhang Yibao | Key Laboratory of Carcinogenesis and Translational Research(Ministry of Education/Beijing), Department of Radiation Oncology, Peking University Cancer Hospital & Institute, Beijing 100142, China | ybzhang66@163.com |
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| Abstract:: |
| Objective To quantify the correlations between Elekta XVI cone beam CT dose and various scanning protocols, providing mathematical models to assess the protocol-dependency of imaging dose during image guided radiotherapy. Methods Based on standard protocols and various combinations of kVp and mA on an XVI mounted on an Elekta Versa HD accelerator, the air KERMA was measured at various positions in a standard PTW CTDI body phantom using calibrated PTW 30009 kV chamber and UNIDOS webline electrometer. Weighted CT dose index (CTDIw) was computed thereafter. SigmaPlot 10.0 was used to fit the measurements against mA and/or kVp yielding empirical functions. Results Under standard protocols, the CTDIw of Varian OBI was only 11.23% (chest) and 9.15% (pelvis) of Elekta XVI. Using the default and other 4 investigated kVp values, the central and peripheral KERMA were both proportional to mA, and yet the slope value a varied dramatically from 0.479 to 6.679. Major affecting factors included kVp settings, measurement locations, and dosimetric metrics, etc. None linear regressions were used to fit kVp against KERMA at various locations and CTDIw (R2>0.997). The differences between all coefficients were statistically significant (P<0.05). The impact of changing both mA and kVp on the dose to phantom center can be described as mGy=(5.917 -0.197×kVp+0.002×kVp2-5.063×10-6×kVp3)×mA. Conclusions Imaging dose of Elekta XVI is strongly dependent on scanning parameters. The proposed mathematical models can be used as efficient and robust indicators of such dependency. |
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