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| Application of VMAT-based hybrid intensity-modulated technique on tumor bed boost after Breast-conservative surgery for breast cancer |
| ZHENG Yaqin, LIU Jianting, CHU Xuegang, CUI Tong, XING Yurong, XING Xiaofen |
| Centre of Radiation Oncology, Shanxi Cancer Hospital, Affiliated Cancer Hospital of Shanxi Medical University, Taiyuan 030013 China |
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Abstract Objective To evaluate dosimetry advantage and clinical application of hybrid intensity-modulated radiotherapy with 3DCRT/VMAT in radiotherapy with tumor bed boost after breast-conservative surgery.Methods Ten patients with breast cancer after breast-conservative surgery were enrolled. Under the same optimization conditions, the VMAT-based hybrid planning (3DCRT+VMAT) and the IMRT-based hybrid planning (3DCRT+IMRT) are designed respectively.The conformity index (CI), homogeneity index (HI), volume of exposure dose on organs at risk in patients from two plans were compared.Results According to the hybrid plan of 3DCRT+VMAT, D95 of Planning Target Volume (PTV) is 50.29±0.25, which is superior to that from 3DCRT+IMRT, 50.69±0.20(P<0.05). There was neither statistical difference of D95 and PTV between two plans, nor difference of CI and HI of pretreatment gross tumor volume (PGTV). In the comparison with exposure dose volume delivered to the heart in two plans, the values of V30 and Dmean in the plan of 3DCRT+VMAT were lower than the ones in 3DCRT+ IMRT(P<0.05). Dmean of the contra-lateral breast in the 3DCRT+VMAT group is 1.31±0.44, that is inferior to the group of 3DCRT+IMRT, which is 1.88±0.28(P<0.05). While V5, V10, V20, Dmean of ipsilateral lung dose and Dmean of cardiac and contra-lateral lung dose had no statistical difference (P>0.05). The monitor units (MU) of 3DCRT/VMAT Plan were 31%(P<0.05) less than that of 3DCRT+IMRT Plan, while the average treatment time of the former plan was 38%(P<0.05) less than the latter.Conclusion Compared with the IMRT-based hybrid plan, the VMAT-based hybrid plan better protects the heart and the healthy breast while ensuring the conformity and uniformity of the target area, and significantly shortens the schedule execution time. Therefore, it has a high potential for clinical application.
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Received: 07 June 2018
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