电子射野影像系统测量鼻咽癌调强放疗的摆位误差
鼻咽肿瘤；,放射疗法；,体位；,图像处理,计算机辅助,,鼻咽肿瘤；,放射疗法；,体位；,图像处理，计算机辅助,1对象与方法,2结果,3讨论,参考文献：
摘要: 目的 分析鼻咽癌调强放射治疗(IMRT)的摆位误差情况，从而确定摆位扩边的大小。方法 选取IMRT的鼻咽癌患者36例，放射治疗过程中每周拍摄电子射野影像片(正侧位)一次，共拍摄电子射野影像片372张。电子射野影像系统(EPID)下将电子射野影像片与数字重建射线影像(DRR)配准，分别测定X轴(左右方向)、Y轴(上下方向)和Z轴(前后方向)的摆位误差。结果 所有电子射野影像片中，各个方向约90.6%的摆位误差≤3 mm，99.2%≤5 mm。总体系统误差分别为X轴-0.5 mm(±1.2 s)，Y轴-0.5 mm(±1.4 s)，Z轴-0.9 mm(±1.5 s)，随机误差的标准差分别为±0.3,±0.2和±0.3 mm；各个方向的摆位扩边值分别为3.2 ,3.6和4.0 mm。 结论 鼻咽癌IMRT具有一定程度的摆位误差。在EPID系统下进行实时摆位误差纠正，可进一步降低摆位系统误差和随机误差，提高摆位精度。关键词: 鼻咽肿瘤； 放射疗法； 体位； 图像处理，计算机辅助
Setup Verification Using Electronic Portal Imaging
for Nasopharyngeal Carcinoma Intensity Modulated Radiation Therapy
Pan Caizhu, Pan Jianji, Chen Chuanben， Zhang Xiuchun, Li Jinlian
Department of Radiation Oncology， Teaching Hospital of Fujian Medical University, Fujian Provincial Tumor Hospital， Fuzhou 350014， China
ABSTRACT: ObjectiveTo investigate the setup verification using electronic portal imaging for nasopharyngeal carcinoma intensity modulated radiation(IMRT).Methods Thirty six patients were enrolled in study.Electronic portal images(EPI) were acquired once every week in the radiation course and a total 372 anterior or lateral isocentric EPI were compared to digitally reconstructed radiograph(DRR) using electronic portal imaging device(EPID). Results About 90.6% of all translational setup errors were ≤3 mm, and 99.2%≤5 mm. The overall systematic error was -0.5 mm(±1.2 s) in Xaxis(rightleft direction), -0.5 mm(±1.4 s) in Yaxis(superiorinferior direction) and -0.9 mm(±1.5 s) in Zaxis(anteriorposterior direction). The corresponding s of the random errors were ±0.3, ±0.2 and ±0.3 mm. The estimated margins required for CTVPTV were calculated according to the van Herk formula was 3.2, 3.6 and 4.0 mm, respectively. Conclusion There exists some extent of setup error in nasopharyngeal carcinoma IMRT. Online correction of setup error using EPID in order to reduce systematic error and random error and then improve setup precision. ......
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