130例放疗病人摆位误差分析

摘要

目的：利用MV级电子射野影像系统（ EPID）对130例放疗病人摆位误差进行分析。方法：选取头颈部肿瘤放疗患者30例，胸部肿瘤放疗患者50例，盆腔肿瘤放疗患者50例，使用6MV X线通过EPID获得0°和90°两射野的实时位置验证片，并与计划系统产生的数字化重建影像的验证片进行对照，计算并分析所测定的摆位误差。结果：3％的头颈部患者摆位误差超过3mm，20％的胸部患者摆位误差超过5mm，10％的盆腔患者摆位误差超过5mm，对这些超过误差范围的患者重新调整位置，达到治疗要求。各部位在X轴（左右方向）、Y轴（头脚方向）、Z轴（前后方向）三个方向的平均摆位误差分别为头颈部1.59mm、1.38mm、1.42mm，胸部2.40mm、2.52mm、2.01mm，盆腔2.11mm、2.35mm、1.98mm。结论：利用EPID可以有效检测放射治疗中的摆位误差，提高摆位的准确性和重复性，是放射治疗质量保证的重要手段。%Objective:To analyze the setup error of 130 patients treated with radiotherapy by MV electronic portal imaging system( EPID). Methods:Selected 30 head and neck cancer patients,50 chest cancer patients and 50 pelvic cancer patients. Obtained real-time verification sheet of 0° and 90° two radiation field using EPID by 6MV X ray, and compared with verification sheet generated by the planning system,calculated and analyzed the setup error. Re-sults:The setup error of three percent of the head and neck patients more than 3mm,twenty percent of chest and ten percent of the pelvic patients exceed 5mm. We readjusted for these patients whose setup error out of range,and reached the treatment requirements. The average error of various parts of the X-axis( left -right direction),Y-axis ( head-feet direction)and Z -axis( front -rear direction )were:the head and neck was 1. 59mm,1. 38mm and 1. 42mm,the chest was 2. 40mm,2. 52mm,2. 01mm and the pelvic was 2. 11mm,2. 35mm,1. 98mm. Conclusion:It's effective to detect the setup error of the radiotherapy by EPID and could improve the accuracy and repeatability of po-sitioning.