非小细胞肺癌不同调强放疗方案的剂量学对比研究

目的 探讨非小细胞肺癌调强放疗计划设计的合理方案。方法 对11例非小细胞肺癌患者分别制定2种放疗计划:PTV60计划的PTV为(GTV+6～8mm)+呼吸动度+摆位误差,对PTV获得60Gy处方剂量进行归一;PTV70计划的PTV为GTV+呼吸动度+摆位误差,对PTV获得70Gy处方剂量进行归一。通过剂量体积直方图分析2种治疗计划的靶区剂量分布和危及器官受量,并进行剂量学的对比研究。结果 PTV70计划接受60Gy剂量的靶区体积明显高于PTV60计划,两组在靶区剂量均匀性方面相似。PTV70计划的肺V₂₀较PTV60计划平均下降(1.69±0.42)%,两组相比差异有统计学意义(t=0.047,P=0.002);肺V₅平均下降(1.29±1.09)%,两组相比差异无统计学意义。结论 在非小细胞肺癌调强放疗设计中,PTV70计划优于PTV60计划。

Dosimetric evaluation of different IMRT treatment plans for non-small cell lung cancer

Objective To investigate the optimal treatment planning of intensity modulated radiotherapy (IMRT) for non-small cell lung cancer(NSCLC). Methods Two types of treatment plans were designed for 11 patients with inoperable NSCLC disease. In the first plan(PTV60 plan), 60 Gy was prescribed to the planning target volume(PTV) which was created using CTV(GTV+6-8 mm) plus the margin for organ motion and setup uncertainties. In the second plan(PTV70 plan), 70 Gy was prescribed to the PTV which was created using GTV plus the margin for organ motion and setup uncertainties. The dose-volume histogram, the planning target volume coverage,and other dosimetric parameters of normal structures were compared between the two plans. Results These two plans were not significantly different in the dose heterogeneity, but commpared with the PTV60 plan,the PTV70 plan significantly improved 60 Gy volume with regard to PTV coverage. The values of V ₂₀ and V ₅ of lung were reduced in average by (1.69±0.42)%,and (1.29±1.09)% (t=0.047,0.264, P =0.002), respectively. ConclusionsThe planning of 70 Gy to the PTV using GTV plus the margin for organ motion and setup uncertainties might be better than that of 60 Gy to the PTV using CTV(GTV+6-8 mm) plus the margin for organ motion and setup uncertainties.