| Zhang Haojia,You Shihu,Jin Haijie,Zhang Yi,Luo Yuanqiang,Wang Zhiyong,Xu Congfeng,Gan Jiaying,Hu Yinxiang.Effects of gantry acceleration limitations on VMAT plans[J].Chinese Journal of Radiological Medicine and Protection,2021,41(9):659-664 |
| Effects of gantry acceleration limitations on VMAT plans |
| Received:March 29, 2021 |
| DOI：10.3760/cma.j.issn.0254-5098.2021.09.004 |
| KeyWords:Gantry acceleration Dosimetry Treatment time Gamma passing rate |
| FundProject:贵州省科技计划项目（黔科合LH字【2016】7398） |
| Author Name | Affiliation | E-mail | | Zhang Haojia | Department of Oncology, Affiliated Hospital of Guizhou Medical University, Department of Oncology of Affiliated Cancer Hospital of Guizhou Medical University, Guiyang 550004, China | | | You Shihu | Department of Oncology, Affiliated Hospital of Guizhou Medical University, Department of Oncology of Affiliated Cancer Hospital of Guizhou Medical University, Guiyang 550004, China | | | Jin Haijie | Department of Oncology, Affiliated Hospital of Guizhou Medical University, Department of Oncology of Affiliated Cancer Hospital of Guizhou Medical University, Guiyang 550004, China | | | Zhang Yi | Department of Oncology, Affiliated Hospital of Guizhou Medical University, Department of Oncology of Affiliated Cancer Hospital of Guizhou Medical University, Guiyang 550004, China | | | Luo Yuanqiang | Department of Oncology, Affiliated Cancer Hospital of Guizhou Medical University, Guiyang 550004, China | | | Wang Zhiyong | Department of Oncology, Affiliated Cancer Hospital of Guizhou Medical University, Guiyang 550004, China | | | Xu Congfeng | Department of Oncology, Affiliated Cancer Hospital of Guizhou Medical University, Guiyang 550004, China | | | Gan Jiaying | Department of Oncology, Affiliated Hospital of Guizhou Medical University, Department of Oncology of Affiliated Cancer Hospital of Guizhou Medical University, Guiyang 550004, China | | | Hu Yinxiang | Department of Oncology, Affiliated Hospital of Guizhou Medical University, Department of Oncology of Affiliated Cancer Hospital of Guizhou Medical University, Guiyang 550004, China | hyx_wengan@163.com |
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| Abstract:: |
| Objective To study the effects of gantry acceleration limitations of a linear accelerator (linac) on the dosimetry of volumetric modulated arc therapy (VMAT) plans, machine efficiency, and dose verification result of VMAT plans and to explore the optimal selection of gantry motion models in the Pinnacle treatment planning system. Methods Ten cases of nasopharyngeal carcinoma, non-small cell lung cancer, sigmoid adenocarcinoma with retroperitoneal lymph node metastasis, and invasive ductal carcinoma of the breast were each selected for this study. Then two models were set up in the Pinnacle v9.10 treatment planning system, namely the one allowing gantry acceleration and the one limiting gantry acceleration. The same field arrangement, optimized target parameters, and optimized weights of VMAT plans were adopted in the two models, in order to analyze the dosimetric variations in targets and organs at risk (OARs) and compare the differences in treatment time and gamma passing rates. Results The treatment time of the enrolled patients under the model allowing gantry acceleration was significantly lower than that of the patients under the model limiting gantry acceleration was adopted (t=-6.751, -0.209, -19.523, -28.999; P< 0.05) and decreased by 15.27%, 18.07%, 19.71%, and 28.75%, respectively. Meanwhile, the conformity and uniformity of target areas were affected, while there was no statistical significance in the gamma passing rates in the validation of VMAT plans (P>0.05). For the cases of nasopharyngeal carcinoma (NPC), the maximum dose to brainstem PRV increased by 1.25%. For the cases of lung cancer, the maximum dose to the spinal cord and lung V20 increased by 1.19% and 1.21%, respectively, while lung V5 decreased by 1.21%. For the cases of sigmoid adenocarcinoma with retroperitoneal lymph node metastasis, the mean doses to bilateral kidneys, livers, small intestine, and colon all increased. For the cases of breast cancer, lung V10 on the opposite side of cancer increased by 1.66% and the mean dose to the lungs on the same side of cancer decreased by 7.45%. Conclusions The model allowing gantry acceleration allows the treatment time to be significantly shortened and the treatment efficiency improved. Although this model had the shortcomings such as affecting the conformity and uniformity of target areas to a certain extent and increasing the doses to some OARs, clinical requirements for dosimetry were still met. Therefore, it is recommended to use the model allowing gantry acceleration in the Pinnacle planning system. |
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