M6型射波刀立体定向放疗系统的验收测试

Acceptance test of M6 CyberKnife stereotactic radiotherapy system

目的:对M6型射波刀立体定向放疗系统的各项技术指标进行临床验收测试,评估其安全性及精确性。方法:参考Accuray公司及国内外相关标准与方法,对M6型射波刀的KUKA机器臂、患者定位、目标定位、可变准直器、直线加速器、治疗计划等6个子系统及端到端综合照射精度进行检测与评估。结果:机器人系统所有节点到位偏差平均值≤0.08 mm,最大值≤0.311 mm。患者治疗床系统偏差:前后(x)方向=0.4 mm、左右(y)方向=0.1 mm、上下(z)方向=0 mm、左右旋转(r)方向=0.1°、头脚旋转(p)方向=0°。目标定位系统:A影像中心偏差x=0.23 mm、y=-0.31 mm,B影像中心偏差x=0.28 mm,y=-0.35 mm;目标定位追踪偏差x=0 mm、y=0.1 mm、z=0.1 mm、r=0.1°、p=-0.1°。iris准直器各尺寸重复性最大偏差0.32 mm。直线加速器系统:SAD=800 mm处光射野一致性精度为x=0.23 mm、y=0.35 mm;射束性能指标中剂量稳定性0.06%,剂量输出线性偏差≤0.53%,iris准直器透射率0.09%、fixed准直器透射率0.14%;孔径60 mm fixed准直器,其半影=4.2 mm、对称性=100.8%、平坦度=109.7%;最大剂量深度为15.5 mm,射线质TPR^(20)_(10)等于0.633。治疗计划系统:影像几何精度x=0.071 mm,y=-0.173 mm,z=0.361 mm;计划点剂量精度0.08%;机器跳数手工验算精度0.04%。E2E测试:fixed准直器追踪精度为0.47 mm(颅骨追踪)、0.45 mm(金标追踪)、0.77 mm(脊柱追踪)、0.50 mm(同步呼吸追踪)、0.42 mm(肺追踪),iris准直器相应的追踪精度为0.23、0.69、0.70、0.51、0.73 mm。结论:M6型射波刀作为亚毫米级的立体定向放疗外科设备,各项参数测试结果均优于验收标准,其精确性、可靠性均满足临床要求。

Objective To conduct a clinical acceptance test on M6 CyberKnife stereotactic radiotherapy system for evaluating its safety and accuracy.Methods Referring to the standards and methods of Accuray and relevant domestic and international standards,the 6 subsystems of M6 CyberKnife including KUKA robot,patient positioning,target positioning,variable collimator,linear accelerator and treatment plan were evaluated,and an end-to-end test was carried out to analyze its overall irradiation accuracy.Results The average deviation of all nodes in the robot system was≤0.08 mm,and the maximum was≤0.311 mm.The system deviation of treatment couch was as follow:anterior-posterior(x)=0.4 mm,left-right(y)=0.1 mm,superior-inferior(z)=0 mm,left-to-right rotation(r)=0.1°,superior-to-inferior rotation(p)=0°.In target positioning system,A image center deviations were x=0.23 mm,y=-0.31 mm,and B image center deviations were x=0.28 mm,y=-0.35 mm;the tracking deviations were as follow:x=0 mm,y=0.1 mm,z=0.1 mm,r=0.1°,p=-0.1°.The maximum repeatability deviation of each size of the iris collimator was 0.32 mm.For linear accelerator,the field consistency deviations at SAD=800 mm were x=0.23 mm,y=0.35 mm.The evaluation on beam performance showed that the dose stability,dose output linear deviation,iris transmittance and fixed transmittance were 0.06%,≤0.53%,0.09%and 0.14%,respectively.The penumbral,symmetry and flatness of 60 mm fixed collimator were 4.2 mm,100.8%and 109.7%,respectively.The maximum dose depth was 15.5 mm,and the TPR^(20)_(10) was 0.633.For treatment planning system,the image geometric deviations were x=0.071 mm,y=-0.173 mm,z=0.361 mm;planning point dose deviation was 0.08%;and the deviation of monitor units in manual calculation was 0.04%.End-to-end test revealed that the accuracies of fixed collimator were 0.47 mm for 6D skull tracking,0.45 mm for Fiducial tracking,0.77 mm for Xsight spine tracking,0.50 mm for synchrony respiratory tracking,-0.42 mm for lung tracking,and that the tracking accuracies of iris collimator were 0.23,0.69,0.70,0.51 and 0.73 mm,respectively.Conclusion M6 CyberKnife as a sub-millimeter-level stereotactic radiosurgery equipment satisfy the acceptance criteria,and its accuracy and reliability meet the clinical requirements.