协和医学杂志

2014, v.5(02) 179-183

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直肠癌术前容积调强与固定野调强技术的剂量学比较
Dosimetric Comparison between Preoperative Volumetric Modulated Arc Therapy and Fixed-field Intensity-modulated Radiotherapy for Rectal Cancer

杨波;庞廷田;孙显松;胡克;邱杰;张福泉;
YANG Bo;PANG Ting-tian;SUN Xian-song;HU Ke;QIU Jie;ZHANG Fu-quan;Department of Radiation Oncology,Peking Union Medical College Hospital,Chinese Academy of Medical Sciences & Peking Union Medical College;

摘要(Abstract):

目的比较对直肠癌术前患者应用固定野调强(fixed-field intensity-modulated radiotherapy,FF-IMRT)和容积调强(volumetric modulated arc therapy,VMAT)两种计划方式进行术前放射治疗的剂量学差异。方法选择15例直肠癌术前进行调强放疗的患者行CT模拟定位,勾画靶区及危及器官,对同一CT图像设计FF-IMRT计划和VMAT计划。评估靶区及危及器官的剂量分布。结果 VMAT计划组和FF-IMRT计划组靶区覆盖度均能满足处方剂量要求。与FF-IMRT计划组相比,VMAT计划组计划靶区(planning target volume,PTV)105%覆盖度、Dmean及Dmax均增加(P=0.011,P=0.017,P=0.006),适形度指数减低(P=0.008),而均匀性指数差异无统计学意义(P=0.193)。与FF-IMRT计划组相比,VMAT计划组膀胱V50增加约15%(P=0.009),Dmax平均值增加0.7 Gy(P=0.003);小肠V30降低10%(P=0.004),Dmax平均值增加0.9 Gy(P=0.000);骨髓V10、V30、V40分别降低2%、10%、10%(P=0.000,P=0.000,P=0.000),Dmean平均值降低1.7 Gy(P=0.000);左右股骨头D5分别降低3.2 Gy、2.4 Gy(P=0.000,P=0.000);全身V10、V20、V30、V40也明显降低(P=0.003,P=0.000,P=0.000,P=0.004)。VMAT计划组较FF-IMRT计划组机器跳数(monitor units,MU)平均值减少50%(P=0.000)。结论直肠癌术前患者采用VMAT技术,可以获得等同于或优于FF-IMRT计划的剂量分布,患者治疗时间明显缩短,MU明显降低。
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 planning 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 V50of the bladder in the VMAT plan group was increased by about15%( P = 0. 009),and the Dmax increased by 0. 7 Gy( P = 0. 003); the V30of 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 V40of the bone marrow reduced by 2%,10%,and 10%( P = 0. 000,P = 0. 000,and P = 0. 000),and the Dmean reduced by 1. 7 Gy( P = 0. 000); the D5of 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 V40of 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 cancer,preoperative VMAT can achieve equivalent or superior dose distribution compared with the FF-IMRT. In addition,VMAT can increase the number of patients treated per hour and reduce waiting time by shortening treatment time and reducing treatment MU.

关键词(KeyWords): 直肠癌;放射治疗;剂量学;固定野调强放疗;容积调强放疗
rectal cancer;radiotherapy;dosimetry;fixed-field intensity-modulated radiotherapy;volumetric modulated arc therapy

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作者(Author): 杨波;庞廷田;孙显松;胡克;邱杰;张福泉;
YANG Bo;PANG Ting-tian;SUN Xian-song;HU Ke;QIU Jie;ZHANG Fu-quan;Department of Radiation Oncology,Peking Union Medical College Hospital,Chinese Academy of Medical Sciences & Peking Union Medical College;

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