15例非小细胞肺癌IMRT计划与IGRT计划剂量学比较研究

目的非小细胞肺癌患者通过图像引导放疗技术确定PTV外扩数值，与常规三维调强计划（CT—IMRT）进行剂量学比较研究。方法选取15例病理组织学确诊的非小细胞肿瘤患者，每周行1次肺部CBCT扫描，每次在放疗前、放疗后分别扫描，得到数据依据二参数法得到三维方向外扩距离，按照外扩距离数据重新勾画靶区并制定计划（CT—IGRT），并与原计划（CT—IMRT）的PTV、双肺、脊髓、心脏的受量、体积进行比较，差异行配对t检验；并依据LymanNTCP模型设计正常组织并发症概率（NTCP）程序，比较2种计划的肺组织NTCP，差异行非参数wilcoxson检验。结果校正后PTV外扩值较前减小。校正后肺平均剂量减小，2种计划有统计学差异。校正后随双肺受照体积增加，经CBCT校正后NTCP有下降趋势，V5、V10、V20、V30、V40、V50CT-IGRT比CT-IMRT明显减低（P均〈0．05）。结论利用CBCT技术校正后可减小摆位误差，缩小PTV外扩数值，精确PTV外扩距离，减小双肺平均受照剂量，降低正常组织并发症概率。

Dosimetry comparison study of IMRT and IGRT plan for Non-small cell lung cancer in 15 patients

Objective To conduct a dosimetry comparison study of non-small cell lung cancer treated by image-guided radiotherapy technology, which determines PTV extended numerical and by regular 3D intensity-modulated plan （CT-IMRT）. Methods 15 patients with non-small cell lung cancer were in the study. Two sets image were acquired every week before and after radiotherapy. The targeted volume was delineated, the plan （CT-IGRT） was made according to the extended distance data and compared with the former plan for dose-volume histogram of PTV, lung, spinal-cord and heart. The differences of two plans were analyzed by T sign rank test. The NTCP differences between the two plans were compared and analyzed by wilcoxson test. Results PTV extended values decreased obviously and the mean dose of lung redueed significantly after correction. The two plans had statistical difference. The double lung volume increased. NTCP had a downward trend after CBCT correction and VS, V10, V20, V30, V40, V50 reduced obviously （P 〈0.05）. Conclusion The use of CBCT technology could reduce the beam position error after correction, narrow the PTV extended numerical and make PTV extended distance precise. The average illuminated double lung dose and the probability of normal tissue complication were reduced.