Abstract：Objective To investigate the application of Auto Flash Margin (AFM) of Monaco treatment planning system in
postoperative radiotherapy for left breast cancer. Methods A total of 16 cases of breast cancer after radical surgery were
selected. The plan design of volumetric modulated arc therapy (VMAT) with AFM values of 0.5, 1 and 2 cm as AFM0.5,
AFM1.0, AFM2.0, was carried out for each enrolled case. The dosimetric differences of planning target volume (PTV) target
area homogeneity index (HI), conformity Index, dosimetric differences of lung, heart and skin dose Dmean and X-ray voxel
Monte Carlo (XVMC) algorithm characteristic parameters of radiotherapy plan were studied. Results The Dmean and V107%
dosimetric indexes of PTV of Monte-Carlo algorithm in Monaco treatment planning system met the dosage requirements
of prescription, but there were statistical differences (P<0.05). In terms of target hot spot dose V107%, AFM2.0 group was
the smallest (2.57%±1.52%). AFM0.5 and AFM1.0 groups were higher and similar with average value of 10.09%±1.72%
and 11.02%±0.15%, The difference was statistically significant (P<0.05). The Dmean of the target area was similar, and the
smallest was (5175.650±4.200) cGy in AFM2.0 group. AFM0.5 and AFM1.0 groups were higher and closer with average value of
(5210.200±5.400) cGy and (5219.600±4.200) cGy, The difference was statistically significant (P<0.05). In the dose evaluation
results of Lung_Ipsi V20 and Lung_Ipsi Dmean, AFM0.5 group and AFM1.0 group were higher than AFM2.0 group, and the
difference was statistically significant (P<0.05). There were no significant differences in Lung_Contra V5 and Heart
Dmean among the three groups. In the comparison of grating configuration at the same angle, the three groups of gratings all form an
obvious air region. In the comparison of XVMC algorithm feature parameters, AFM2.0 group had less monitor unit, higher quantum
efficiency and slightly higher optimization time, and the segment of the three groups was close to 290 control points preset in the
plan. AFM2.0 group had better Dmean than the other three groups (P<0.05). Conclusion When using the Monaco treatment planning
system to design the VMAT plan after radical mastectomy, an AFM value of 2 cm is recommended.
华小龙a，徐文静a，张倜然b，葛迅a，邹辉a，朱磊a，包凯b，刘庆文b. Auto Flash Margin功能在左乳腺癌术后放
疗中的应用研究[J]. 中国医疗设备, 2024, 39(4): 53-59.
HUA Xiaolonga, XU Wenjinga, ZHANG Tiranb, GE Xuna, ZOU Huia, ZHU Leia, BAO Kaib, LIU Qingwenb. Application of Auto Flash Margin Function in Postoperative Radiotherapy for Left Breast Cancer. China Medical Devices, 2024, 39(4): 53-59.
