| 射野大小对全脑调强放疗计划EPID验证结果的影响 |
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| 引用本文： | 张瑾,聂鑫,熊祎.射野大小对全脑调强放疗计划EPID验证结果的影响[J].中国医学物理学杂志,2020,37(6):661-665. |
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| 作者姓名： | 张瑾 聂鑫 熊祎 |
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| 作者单位： | 1.武汉大学中南医院药学部， 湖北 武汉 430071； 2.华中科技大学同济医学院附属协和医院肿瘤中心， 湖北 武汉 430022； 3.武汉大学物理科学与技术学院， 湖北 武汉 430072 |
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| 摘 要： | 目的:利用电子射野影像系统（EPID）对全脑调强放疗计划进行γ测试，寻找计划设计对测试结果的影响，以此分析如何优化全脑调强计划以及推测EPID在剂量验证方面的局限性。方法:选取67例全脑放疗患者，对其放疗计划用加速器自带的EPID进行计划验证，对于容积旋转调强放疗（VMAT）计划统计并分析X方向射野大小与γ（3 mm/3%）通过率的关系，对于调强放疗（IMRT）对比分析大野调强和分野调强计划γ（3 mm/3%）通过率的差异。结果:VMAT计划验证结果发现X方向小于15 cm的射野γ（3 mm/3%）通过率普遍优于大于等于15 cm的射野，利用SPSS软件进行t检验，发现结果具有统计学意义（t=-3.828, P<0.05）；IMRT验证结果发现，X方向大于等于15 cm的射野会包含两个子野，合野验证时其交叠部分γ（3 mm/3%）通过率较差，而采用分野验证时，由于无交叠则通过率普遍较好。结论:全脑放疗VMAT计划将X方向射野控制在15 cm以内可以提升多叶准直器调节能力，并提高EPID验证的γ（3 mm/3%）通过率；EPID原件对低剂量区的响应偏差会导致全脑IMRT大野调强计划两子野交叠处γ（3 mm/3%）通过率较差，改用分野验证可以显著消除这种影响。
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| 关 键 词： | 电子射野影像系统 调强放疗 射野 全脑 计划验证 |
Effect of field size on EPID verification of whole-brain radiotherapy plan |
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| ZHANG Jin,NIE Xin,XIONG Yi.Effect of field size on EPID verification of whole-brain radiotherapy plan[J].Chinese Journal of Medical Physics,2020,37(6):661-665. |
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| Authors: | ZHANG Jin NIE Xin XIONG Yi |
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| Affiliation: | 1. Department of Pharmacy, Zhongnan Hospital of Wuhan University, Wuhan 430071, China 2. Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China 3. School of Physics and Technology, Wuhan University, Wuhan 430072, China |
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| Abstract: | Abstract: Objective To verify whole-brain radiotherapy plan by electronic portal imaging device (EPID) using γ test for discussing the effects of plan design on test results, thereby analyzing how to optimize whole-brain radiotherapy plans and speculating the limitations of EPID in dose verification. Methods Sixty-seven patients scheduling for whole-brain radiotherapy were selected and their radiotherapy plans were verified by EPID on the accelerator. For volumetric modulated arc therapy (VMAT) plans, the relationship between X-direction field size and γ (3 mm/3%) passing rate was statistically analyzed. For intensity-modulated radiotherapy (IMRT) plans, the differences in γ (3 mm/3%) passing rate between whole-field and split-field plans were analyzed. Results The result of VMAT plan verification showed that the γ (3 mm/3%) passing rates of plans with X-direction field size less than 15 cm were generally superior to the ones with their X-direction field size greater than or equal to 15 cm, and the results of t-test by SPSS software also verified that the results had statistical significance (t=-3.828, P<0.05). The result of IMRT plan verification showed that the radiation fields with X-direction greater than or equal to 15 cm contained two sub-fields. The γ (3 mm/3%) passing rate was lower in their overlapping areas, while splitting these fields could gain a much better results for the elimination of overlapping areas. Conclusion For whole-brain VMAT plans, controlling the X-direction field size within 15 cm can improve the adjusting ability of multi-leaf collimators, thus improving γ (3 mm/3%) passing rate of EPID verification. Meanwhile, the deviation of the response of EPID to low dose area will lead to a lower γ (3 mm/3%) passing rate at the overlapping areas of two sub-fields inside the radiation field of whole-brain IMRT plans, but using split-field verification can significantly eliminate the effect. |
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| Keywords: | Keywords: electronic portal imaging device intensity-modulated radiotherapy radiation field whole brain plan verification |
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