Dosimetric Comparison between Preoperative Volumetric Modulated Arc Therapy and Fixed-field Intensity-modulated Radiotherapy for Rectal Cancer
10.3969/j.issn.1674-9081.2014.02.011
- VernacularTitle:直肠癌术前容积调强与固定野调强技术的剂量学比较
- Author:
Bo YANG
1
;
Ting-Tian PANG
;
Xian-Song SUN
;
Ke HU
;
Jie QIU
;
Fu-Quan ZHANG
Author Information
1. 中国医学科学院 北京协和医学院 北京协和医院放疗科
- Keywords:
rectal cancer;
radiotherapy;
dosimetry;
fixed-field intensity-modulated radiotherapy;
volumetric modulated arc therapy
- From:
Medical Journal of Peking Union Medical College Hospital
2014;(2):179-183
- CountryChina
- Language:Chinese
-
Abstract:
Objective To compare the dosimetric characteristics of preoperative volumetric modulated arc therapy ( VMAT) and fixed-field intensity-modulated radiotherapy ( FF-IMRT) for rectal cancer .Methods The CT images of 15 patients with rectal cancer were transferred into Eclipse planning system .FF-IMRT and VMAT plans were optimized on an Eclipse treatment planning system using beam data generated for Varian Trilogy linear accelerator .Same institutional dose-volume constraints for rectal cancer were used in both techniques .Targets and organs at risk were evaluated .Results The target volume coverage could meet the requirement of described dosage in both VMAT plan group and FF-IMRT plan group .Compared with the FF-IMRT plan group , the plan-ning target volume ( PTV) 105% ( PTV105%) coverage, Dmean, and Dmax significantly increased in the VMAT plan group ( P=0.011, P=0.017, and P=0.006, respectively), the radiation conformity index (CI) significantly decreased ( P=0.008 ) , and the homogeneity index showed no significant difference ( P=0.193 ) . Compared with the FF-IMRT plan group , the V50 of the bladder in the VMAT plan group was increased by about 15%( P=0.009 ) , and the Dmax increased by 0.7 Gy ( P=0.003 );the V30 of the small intestine decreased by 10% (P=0.004), and the Dmax was increased by 0.9 Gy (P=0.000); the V10, V30, and V40 of the bone marrow reduced by 2%, 10%, and 10%( P=0.000 , P=0.000 , and P=0.000 ) , and the Dmean re-duced by 1.7 Gy ( P=0.000 );the D5 of the left and right femoral heads reduced by 3.2 Gy and 2.4 Gy ( P=0.000 , P=0.000 ); the V10 , V20 , V30 , and V40 of the body also significantly decreased ( P=0.003 , P=0.000 , P=0.000 , and P=0.004 ) .The VMAT group also had significantly lower number of monitor units ( MU) when compared with the FF-IMRT plan group ( P=0.000 ) .Conclusions In patients with rectal canc-er, preoperative VMAT can achieve equivalent or superior dose distribution compared with the FF -IMRT.In addi-tion, VMAT can increase the number of patients treated per hour and reduce waiting time by shortening treatment time and reducing treatment MU .
