Abstract：Objective To compare the setup accuracy of different breast bracket angles after postoperative radiotherapy for breast cancer,
so as to provide a reference for PTV projection. Methods A total of 24 breast cancer patients treated with Varian Halcyon accelerator
from December 2019 to April 2020 were selected. All patients were fixed with breast brackets and randomly divided into group A
(0°) and group B (7.5°) according to bracket Angle. All patients were matched with the CT images after MV-CBCT scan by rigid
registration, and the setup errors of three orientations were obtained. Independent sample T-test or calibration T-test were performed
according to whether the variance of the two groups of data was homogeneous. And calculating the CTV-PTV expansion distance
of two groups. Results The mean±SD of group A and B in the three orientations of x, y and z were as follows: (0.28±0.24) cm,
(0.31±0.28) cm丨 (0.37±0.26) cm, (0.53±0.34) cm丨 (0.38±0.31) cm, (0.46±0.35) cm. The variance of x and y directions was not
homogeneous (P < 0.05), and the corrected t-test was performed, while the independent sample t-test was performed in the z direction.
The difference in y and z orientations was statistically significant (P<0.05). The CTV-PTV expansion distance of group A and B are
0.49 and 0.64 cm (x)丨 0.55 and 0.80 cm (y)丨 0.52 and 0.60 cm (z). Conclusion The mean setup errors of three orientations in the 0°
group were less than that in the 7.5° group, and the 0° mode of the breast bracket had good repeatability. In clinical work, it is
suggested that 0° brackets should be preferred if conditions permit. The use of both brackets presented more singular values, and the
MV-CBCT verification before each treatment of Halcyon was of great value for postoperative radiotherapy of breast cancer patients.
张悦，孙显松，张宇，林敬宇，杨波，于浪，汪之群，胡克，张福泉，邱杰. 基于Halcyon加速器研究乳腺托架倾角对于保乳术后放疗摆位误差的影响[J]. 中国医疗设备, 2021, 36(4): 41-44.
ZHANG Yue, SUN Xiansong, ZHANG Yu, LIN Jingyu, YANG Bo, YU Lang, WANG Zhiqun, HU Ke, ZHANG Fuquan, QIU Jie. Study on the Effect of Breast Bracket Tilt Angle on Radiotherapy Setup Error
after Breast Conserving Surgery Based on Halcyon Accelerator. China Medical Devices, 2021, 36(4): 41-44.
