螺旋断层调强放疗治疗非小细胞肺癌的剂量学研究

Helical tomotherapy for non-small cell lung cancer: A dosimetric study

目的探讨螺旋断层调强放疗(HT)治疗NSCLC的剂量学特点。方法选取5例中央型NSCLC和5例周围型NSCLC患者的CT图像,勾画靶区及正常器官,分别进行HT计划和IMRT计划设计。给予肿瘤靶区(GTV、GTVnd)处方剂量70Gy/33F,临床靶区(CTV、CTVnd)处方剂量60Gy/33F。正常器官限制剂量为脊髓<45Gy,全肺V20<30%,心脏V50<50%,食管V55<50%等,比较两组患者两种治疗计划的差异。结果周围型NSCLC组的HT计划等剂量曲线能更好地包绕靶区;周围型NSCLC组肺的V5均大于60%,中央型NSCLC组肺的V5近似于60%,HT可减少周围型NSCLC组肺的V20-V30,减少中央型NSCLC组肺的V25;两组的两种计划中脊髓、食管、心脏和气管的最大量均低于IMRT组,但c差异无统计学意义。结论 HT计划在周围型NSCLC组较IMRT计划有更好的靶区剂量均匀性及更陡峭的剂量梯度,能降低肺的中高剂量照射体积,但有可能增加肺的低剂量照射体积。

Objective To investigate the dosimetric characteristics of helical tomotherapy（HT） for non-small-cell lung cancer（NSCLC）.Methods CT images,tumor target area and normal organs were selected respectively from 5 patients with central NSCLC and 5 patients with ambient NSCLC to design the HT and IMRT treatment plans.The prescription dose was 70Gy/33F and 60Gy/33F for CTV and CTVnd,respectively.The dose limit was 45Gy for spinal cord,30% for V20 of the total lung,and 50% for V50 of the heart and V55 of the esophagus.Differences in the two plans were compared.Results The dose homogeneities were better in HT plan for ambient NSCLC group.The dose limit was over 60% and close to 60% for V5 of lung in ambient NSCLC group and central NSCLC group,respectively.The dose limit was considerably lower for V20-V30 of the ambient NSCLC group and for V25 of the central NSCLC group after HT.The maximum doses for spinal cord,heart,esophagus and trachea were lower in HT plan than in IMRT plan with no significant difference between the two plans.Conclusion HT plan can give better dose uniformity,dose gradient and healthy tissue savage than IMRT plan.HT plan can reduce the irradiated volume with medium-high doses in patients with NSCLC.However,the increased irradiated volume with low dose needs further investigation.