摆位误差对鼻咽癌和直肠癌放疗剂量投射准确性的影响  

Effects of positioning error on the accuracy of radiotherapy dose delivery for nasopharyngeal and rectal cancers

作　　者：黄洋洋 田玉龙 董胜楠 杨军 王成[1] 侯歌[1] 刘宗文[1] HUANG Yangyang;TIAN Yulong;DONG Shengnan;YANG Jun;WANG Cheng;HOU Ge;LIU Zongwen(Department of Radiation Oncology,the Second Affiliated Hospital,Zhengzhou University,Zhengzhou 450014;Department of Radiation Oncology,the Fifth Affiliated Hospital,Zhengzhou University,Zhengzhou 450052;School of Nuclear Science and Technology,South China University,Hengyang,Hunan 421001;Department of Medical Equipment,the Third Affiliated Hospital,Zhengzhou University,Zhengzhou 450052)

机构地区：[1]郑州大学第二附属医院放疗科,郑州450014 [2]郑州大学第五附属医院放疗科,郑州450052 [3]南华大学核科学技术学院,湖南衡阳421001 [4]郑州大学第三附属医院设备科,郑州450052

出　　处：《郑州大学学报（医学版）》2021年第6期848-854,共7页Journal of Zhengzhou University(Medical Sciences)

基　　金：河南省医学科技攻关计划项目(201401009,2018020161,LHGJ20190304,LHGJ20210407);河南省科技厅科技攻关计划项目(182102310700)。

摘　　要：目的:研究摆位误差对鼻咽癌和直肠癌放疗剂量投射准确性的影响以及两种疾病对摆位误差的容许范围。方法:设计使用5例鼻咽癌9野调强计划和5例直肠癌5野调强计划,利用二维矩阵MatriXX,通过移床分别在X轴和Y轴方向引入±1、±2、±3、±4和±5 mm的摆位误差,用γ通过率评估剂量投射的准确性。比较无摆位误差时鼻咽癌和直肠癌的γ通过率,评估单摆位误差(X轴或Y轴方向)和双摆位误差(X轴和Y轴方向)对鼻咽癌和直肠癌γ通过率的影响。结果:γ通过率≥95.0%被认为剂量投射合格。鼻咽癌患者的γ通过率为(96.02±0.76)%,小于直肠癌患者的(98.81±0.08)%(P=0.001)。鼻咽癌患者X轴或Y轴方向≥±2 mm摆位误差就会导致γ通过率<95%,且随着摆位误差绝对值增大,γ通过率减小;直肠癌患者X轴或Y轴方向在≥±3 mm摆位误差时,γ通过率<95%,且随着摆位误差绝对值增大,γ通过率减小。双摆位误差时,鼻咽癌和直肠癌的γ通过率都小于单摆位误差的γ通过率。结论:放疗过程鼻咽癌对摆位误差的容许程度小于直肠癌;要提高以鼻咽癌为代表的头颈部肿瘤的位置验证频率。Aim:To investigate the effects of positioning error on the accuracy of radiotherapy dose delivery for nasopharyngeal and rectal cancers and the tolerance range of positioning error for both diseases.Methods:Five cases of 9-field IMRT plans for nasopharyngeal cancer and 5 cases of 5-field IMRT plans for rectal cancer were designed to assess the accuracy of dose delivery in terms ofγpassing rate by introducing positioning errors of±1,±2,±3,±4 and±5 mm in the X-axis and Y-axis directions,respectively,through table shifting using the two-dimensional matrix MatriXX.Theγpassing rates of nasopharyngeal and rectal cancers were compared without positioning errors,and the effects of single(X-axis or Y-axis direction)and double(X-axis and Y-axis direction)positioning errors on theγpassing rates of nasopharyngeal and rectal cancers were evaluated.Results:Theγpassing rate≥95%was considered acceptable for dose delivery.Theγpassing rate in the nasopharyngeal cancer group was(96.02±0.76)%,which was smaller than that in the rectal cancer group(98.81±0.08)%(P=0.001).For single positioning errors,an error of≥±2 mm in the X-axis or Y-axis direction in the nasopharyngeal cancer group resulted in theγpassing rate<95%,and theγpassing rate decreased as the absolute value of the error increased;in the rectal cancer group,theγpassing rate was<95%in the X-axis or Y-axis direction with an error≥±3 mm,and theγpassing rate decreased as the absolute value of the error increased.Theγpassing rates of both nasopharyngeal and rectal cancers were smaller than those of the single-direction positioning error plans when the double positioning error was applied.Conclusion:The tolerance of positioning error for nasopharyngeal cancer during radiotherapy is smaller than that for rectal cancer;the frequency of positioning verification should be improved,especially for head and neck tumors represented by nasopharyngeal cancer.

关 键 词：摆位误差 鼻咽癌 直肠癌 γ通过率 

分 类 号：R735.3[医药卫生—肿瘤] R739.6[医药卫生—临床医学]