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[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。
[Objective] To evaluate the effects of different normal lung volume definitions on lung-dose planning of lung cancer radiotherapy. [Methods] Twenty patients with lung cancer undergoing radiotherapy were collected, all of whom were located by CT. Outline GTV, CTV, PTV-GTV, PTV-CTV and OAR in lung cancer target areas. Normal lung volume was defined according to 4 definitions, group A: lung volume included GTV; group B: lung volume minus GTV; group C: lung volume minus CTV; group D: lung volume minus PTV-GTV . Pulmonary dosimetry parameters V5, V20, and MLD were obtained for different lung volumes, and the lung parameters were compared with those of the other three groups respectively. [Results] The definition of different lung volume led to significant changes in the parameters of the lung dose (P values were less than 0.000), and the magnitude of the change of each parameter was positively correlated with the size of GTV. The correlation between lung V20 and V5 and MLD was stronger. When GTV / BTE represent GTV factors, the effect of GTV size on lung dose parameters can be better reflected. [Conclusion] The different definitions of lung volume in lung cancer target area mapping affect normal lung dose.