不同校正系统在鼻咽癌加量调强放射治疗中的摆位误差关系研究

Study on the relationship of setup errors of different correction systems in SIB-IMRT for nasopharyngeal carcinoma

目的:研究兆伏级锥形束CT(MV-CBCT)、ExacTrac X射线图像引导系统(ExacTrac系统)在鼻咽癌患者行加量调强放射治疗(SIB-IMRT)中摆位的重复性误差的关系。方法:选取在医院治疗的82例鼻咽癌患者,分别对患者进行在MV-CBCT与ExacTrac系统下的SIB-IMRT,分析MV-CBCT、Exac Trac系统患者的校正前后x(左右)、y(头脚)和z(前后)的3个平移误差及其对应的旋转误差U、V和W的6个自由度之间的差异,分析MV-CBCT与ExacTrac系统的诊断一致性。结果:Exac Trac系统对患者校正前后x、y、z 3个平移误差及其对应的U、V、W 3个旋转误差之间的差异均有统计学意义(t=48.692,t=28.752,t=12.353,t=26.106,t=13.194,t=16.544;P<0.05);在患者的治疗中对平移方向以及旋转方向进行调整。MVCBCT对患者校正前后不同方向的计算机系统摆位误差、随机摆位误差及系统误差之间的差异有统计学意义(t=74.154,t=20.353,t=10.201;P<0.05);在患者的治疗中对平移方向进行调整。MV-CBCT与ExacTrac系统的诊断一致性较强(Kappa=14.520,P<0.05)。结论:MV-CBCT和ExacTrac系统两种方法的误差调整均可在一定程度上满足临床需求,并可以从6个自由度对患者的精准度进行调整,提升摆位精度和患者的治疗效果,降低周边组织的不良反应。

Objective:To study the relationship of repeatability error of setup between megavoltage cone-beam computed tomography(MV-CBCT)and ExacTrac X-ray imaging guidance system(ExacTrac system)in simultaneous integrated boost intensity-modulated radiation therapy(SIB-IMRT)for patients with nasopharyngeal carcinoma.Methods:82 patients with nasopharyngeal carcinoma were selected to undergo MV-CBCT and ExacTrac system in SIB-IMRT.The differences of 3 translation errors(x:left and right,y:head and foot,z:front and back)of patients who underwent MV-CBCT and ExacTrac system between before and after correction were analyzed,and the corresponding differences of 6 degree of freedom of rotation errors(U,V and W)were further analyzed.And the consistency of diagnosis between MV-CBCT and ExacTrac system also was analyzed.Results:The differences of 3 translation errors(x,y and z)of ExacTrac system on patients between before and after correction,and the differences of 3 corresponding rotation errors(U,V and W)between before and after correction were significant(t=48.692,t=28.752,t=12.353,t=26.106,t=13.194,t=16.544,P<0.05),respectively.The translation direction and the rotation direction were adjusted in the treatment of patients.And the differences of setup error of computer system,random setup error and system error of different directions of MV-CBCT on patients between before and after correction were significant(t=74.154,t=20.353,t=10.201,P<0.05),and the translation direction was adjusted in the treatment of patients.The consistency of diagnosis between MV-CBCT and ExacTrac was higher(Kappa=14.520,P<0.05).Conclusion:The error adjustment of MV-CBCT and ExacTrac system can meet the clinical needs to some extent.And from six degrees of freedom,the accuracy of patients can be adjusted,and the setup precision and therapeutic effect of patients can be enhanced,and the adverse reactions of peripheral tissue also can be reduced.