主动呼吸控制放射治疗肺癌靶区位置误差分析

Analysis of Target Location Errors in Radiation Treatment of Non-Small-Cell Lung Cancer Using Active Breathing Control System

目的:观察将主动呼吸控制(active breathing control,ABC)系统应用于非小细胞肺癌(non-small-cell lung cancer,NSCLC)的三维适形放射治疗(three dimensional conformal radiotherapy,3D-CRT)中所产生的靶区位置误差,分析其产生原因,探讨其在体部立体定向放射治疗(stereotacfic body radiotherapy,SBRT)中应用的可行性。方法:未行手术治疗的II～III期NSCLC患者8例,真空体模固定体位,模拟定位及放射治疗过程中全程应用ABC系统,3D-CRT治疗肺癌原发病灶。首次摆位时,在应用ABC系统状态下,每隔3min以治疗体位在模拟机上拍摄定位片,连续拍摄5次,测定靶区位置误差模拟分次治疗内误差。治疗期间首周每天1次其后每周1次应用电子射野影像装置(electronic portal imaging device,EPID)拍摄验证片,测定靶区位置误差模拟分次治疗间误差。应用iviewGT系统分析分次治疗内及分次治疗间的误差。结果:8例患者分次治疗内误差:X轴(1.02±1.00)mm,Y轴(0.65±0.95)mm;分次治疗间误差:X轴(1.31±1.36)mm,Y轴(1.51±1.33)mm。结论:应用ABC系统后,3D-CRT的分次治疗间及分次治疗的内误差较常规适形放射治疗显著缩小。

Objective：To analyze the comprehensive errors of the active breathing control（ABC） system and the causes when it is applied to three-dimensional conformal radiotherapy（3D-CRT） for non-small-cell lung cancer（NSCLC） and to investigate the feasibility of its application in stereotactic body radiotherapy（SBR） for NSCLC.Methods：A total of 8 patients with phase II-III NSCLC were fixed by the vacuum phantom and treated with 3D-CRT.During the whole process of plan preparation and radiotherapy,ABC system was used to control the relative displacement caused by respiratory movement.Elekta iviewGT system was used to record the displacement of target position in the simulation and treatment.The inter-fractional radiotherapy errors and the intra-fractional radiotherapy errors were analyzed.Results： The overall inter-fractional radiotherapy errors were（1.28±1.02） mm for the X-axis positive direction and（1.07±1.76） mm for the Y-axis positive direction.The overall intra-fractional radiotherapy errors were（1.35±1.63） mm for the X-axis positive direction and（1.38±1.50） mm for the Y-axis positive direction.Conclusions： The inter-fractional radiotherapy errors and intra-fractional radiotherapy errors of 3D-CRT using ABC system were significantly smaller than those of conventional radiotherapy.