不同肺体积定义对肺癌放疗剂量学的影响

Effect of Different Definition for Lung Volume on the Radiation Dosimetry for Lung Cancer

[目的]评估不同的正常肺体积定义对肺癌放疗计划的肺剂量学影响。[方法]收集接受放射治疗的肺癌患者20例,均用CT模拟定位。勾画肺癌靶区GTV、CTV、PTV-GTV、PTV-CTV及危及器官(OAR)。正常肺体积按4种定义分别勾画,A组:双肺体积包含GTV;B组:双肺体积减去GTV;C组:双肺体积减去CTV;D组:双肺体积减去PTV-GTV。获取不同肺体积定义的肺剂量学参数值V5、V20、MLD,以B组为对照组分别与其余三组配对比较肺的剂量学参数。[结果]不同肺体积定义会导致肺剂量参数值显著变化(P值均小于0.000),各参数值变化幅度与GTV大小呈正相关,其中肺V20相关性较V5及MLD强。当以GTV/双侧肺体积代表GTV因素时,能更好地反映GTV大小对肺剂量参数指标的影响。[结论]肺癌靶区勾画中肺体积的不同定义影响正常肺剂量学。

[Purpose] To investigate the effect of different definition for lung volume on the radiation dosimetry for lung cancer. [Methods] Twenty patients with lung cancer were treated with intensity modulated radiation therapy, and the GTV, CTV, PTV of primary tumor and organs at risk were delin- eated. Normal lung volumes with different definitions were divided into four groups, and the differences of V20,V5 and MLD were analyzed by paired t-test. [Resultsl The parameters varied considerably with different definitions of lung volume and the rangeability positively correlated with GTV,especially the V20. When GTV/lung volume represented the GTV,the effect of GTV on the lung dosimetric parame- ters would be better presented.[Conclusion] Different definitions of lung volume have an effect on the lung dosimetric parameters.