Abstract：Objective To investigate the dosimetric comparison of simultaneous integrated boost of volumetric modulated arc therapy
(SIB-VMAT) on the tumor bed after breast-conserving surgery for breast cancer at different sites with and without flattening filter
mode. Methods A total of 42 patients with breast cancer treated in the Department of Radiotherapy of Renmin Hospital of Wuhan
University from January to May 2022 were randomly selected for post breast-conserving lumpectomy simultaneous volume push
radiotherapy, including 22 patients after left breast surgery and 20 patients after right breast surgery. SIB-VMAT was designed for
both groups under the same constraints with flattening filter (FF) and flattening filter free (FFF) mode. The prescription
dose of the target area was 50 Gy/25 times, and the local SIB was up to 60 Gy/25 times. The dosimetry parameters, monitor unit
(MU) and beam exit time of the two groups were compared. Results FFF mode compared with FF mode, the differences in target
area dose were statistically significant (P<0.05) for HI of PTV-tb after left breast-conserving surgery, D98% and Dmean of PTV-tb after
right breast-conserving surgery, and D2% and Dmean of PTV; other target area parameters were not statistically different. The Dmean of
the healthy lung, spinal cord, and contralateral breast in the FFF mode were better than in the FF mode after left breast-conserving
surgery; the Dmean of the healthy lung and Dmax of the spinal cord in the FFF mode were better than in the FF mode after right breastconserving
surgery, and the differences were statistically significant (P<0.05). There was no statistically significant difference
between the two groups of planned parameters for other organs at risk (P>0.05). Compared with the FF mode, the left and right
breast-conserving surgeries in the FFF mode showed a significant increase in MU, but the beam exit time was significantly reduced
(P<0.05). Conclusion All plans can meet the clinical needs, and the FFF mode is better than the FF mode in protecting normal
tissues and has higher treatment efficiency. And the advantage of SIB-VMAT after left breast-conserving surgery in the FFF mode is
more obvious than that of SIB-VMAT after right breast-conserving surgery in protecting normal tissues.
程冬，朱斌，刘文敏，付振明. 有无均整器模式下乳腺癌保乳术后瘤床
同步推量VMAT剂量学研究[J]. 中国医疗设备, 2023, 38(7): 61-66.
CHENG Dong, ZHU Bin, LIU Wenmin, FU Zhenming. Dosimetric Study of SIB-VMAT in Tumor Bed After Breast-Conserving Surgery With or
Without Flattening Filter Mode. China Medical Devices, 2023, 38(7): 61-66.
