Dosimetric Comparison of the SIB-VMAT for Rectal Cancer Using Flattening Filter Mode
and Flattening Filter Free Mode in MONACO Treatment Planning System
GE Shuanga, CHI Huizhena, CHEN Changjiana, LI Huib, WANG Xunc, MA Juna, CHENG Jinxiua, WEI Mina, ZHU Peijuna,
CHENG Shuyuana, YANG Jundonga, YE Shuchenga,b
a. Department of Tumor Radiotherapy; b. Department of Tumor; c. Department of Medical Imaging, The Affiliated Hospital of Jining
Medical University, Jining Shandong 272001, China
Abstract：Objective To investigate the dosimetric difference of the simultaneous integrated boost of volumetric-modulated arc
therapy (SIB-VMAT) for rectal cancer using 6 MV flattening filter (FF) mode and flattening filter free (FFF) mode. Methods A
total of sixteen patients with rectal cancer were randomly selected to design SIB-VMAT plans with FF and FFF modes under the
same constraints. The dose verification was measured by MatriXX detector. The homogeneity index (HI), conformity index (CI) of
targets, monitor unit (MU), control point (CP), beam time and γ pass rate were compared. Results Under the standard of 100% of
the prescribed dose to cover 95% of the PTV volume, the D2% of the PGTV, the Dmean and D50% of the PTV were decreased by 1%
compared with the FF modes. The D98% of PTV was increased by 0.63%. The CI and HI of PTV were improved. The Dmax and V45 of
the intestine and the radiation dose in bladder reduced. The coverage volumes of peripheral dose by 25 Gy, 22.5 Gy and the Dmean of
between target area (P-G) were significantly decreased, with statistical significance (P<0.05). Compared with FFF mode, MU and
CP in FF mode were significantly decreased and the difference was statistically significant (P<0.05). But the planned beam delivery
time was similar, and the difference was not statistically significant (P>0.05). The γ pass rate verified by the plan were all greater than
99% under the criteria of 3%/3 mm. The difference was not statistically significant (P>0.05). But under the criteria of the 2%/2 mm
and 1%/1 mm, the γ pass rate of the FFF model was significantly increased and the difference was statistically significant (P<0.05).
Conclusion The plans of the two modes can meet the clinical requirements. Compared with the FF mode, the FFF mode has obvious
advantages in improving the quality of the plan and protecting the bladder and intestines.
葛双a，郗会珍a，陈长建a，李慧b，王寻c，马俊a，程锦绣a，魏敏a，朱培军a，程淑媛a，杨君东a，叶书成a,b. 基于MONACO计划系统有无均整器模式对直肠癌术后SIB-VMAT计划影响的研究[J]. 中国医疗设备, 2022, 37(3): 43-47.
GE Shuanga, CHI Huizhena, CHEN Changjiana, LI Huib, WANG Xunc, MA Juna, CHENG Jinxiua, WEI Mina, ZHU Peijuna,
CHENG Shuyuana, YANG Jundonga, YE Shuchenga,b. Dosimetric Comparison of the SIB-VMAT for Rectal Cancer Using Flattening Filter Mode
and Flattening Filter Free Mode in MONACO Treatment Planning System. China Medical Devices, 2022, 37(3): 43-47.
