周围型肺癌立体定向放射治疗靶区最高剂量对正常组织的影响

The effect of boosting maximum dose in the target on the normal tissue exposure for peripheral lung cancer patients undergoing stereotactic body radiotherapy

目的:探讨肺癌立体定向放疗中提高靶区最高剂量对正常组织照射剂量的影响,为临床治疗提供剂量学参考依据。方法:收集20例周围型早期肺癌患者的CT图像资料,针对靶区内最高剂量分别设计P_(120%)、P_(115%)、P_(110%)、P_(105%)共4个剂量梯度的放射治疗计划,评价4组计划对靶区剂量、正常肺组织、胸壁和肋骨剂量的影响。结果:4组计划对靶区、胸壁和肋骨剂量影响较大,而对正常肺组织剂量的影响较小。P_(120%)、P_(115%)、P_(110%)和P_(105%)4组计划的靶区平均最高剂量分别为58.9、55.4、53.3和50.5 Gy;对于胸壁剂量,4组计划的平均V_(30)分别为18.4、14.3、12.0和9.1 cc,V_(40)分别为5.3、3.7、2.8和1.5 cc,D_(max)1 cc分别为43.4、41.1、39.7和37.5 Gy;对于肋骨剂量,4组计划的肋骨平均最高剂量分别为47.3、44.4、42.8和40.6 Gy;对于肺剂量,4组计划的中位V5分别为15.2%、15.0%、14.8%和14.6%,V10分别为11.4%、10.9%、10.6%和10.1%,V20分别为5.0%、4.6%、4.4%和4.1%,肺平均剂量分别为4.0、3.8、3.7和3.5 Gy。结论:提高靶区内最高剂量主要影响靶区、胸壁和肋骨剂量,对正常肺组织的剂量影响较小。临床治疗中可尝试根据肿瘤与危及器官的毗邻关系实施个体化治疗策略。

Objective:To investigate the impact of boosting the maximum dose in the target on the normal tissue exposure for peripheral lung cancer patients undergoing stereotactic body radiotherapy.Methods:20 patients with peripheral lung cancer were included.Four groups of treatment plans based on different maximum dose(P_(120%),P_(115%),P_(110%)and P_(105%))of the target were designed respectively.The dose to the tumor,lung,chest wall and rib were compared.Results:We found boosting the maximum dose in the target influenced the tumor,chest wall and the rib dose a great deal while its influence on the lung dose was limited.Specifically,the average maximum dose to the target in the four group plans was 58.9,55.4,53.3 and 50.5 Gy.V_(30) of the chest wall was 18.4,14.3,12.0,9.1 cc.V_(40) was 5.3,3.7,2.8,1.5 cc.D_(max)1 cc of the chest wall was 43.4,41.1,39.7 and 37.5 Gy.The maximum dose to the rib was 47.3,44.4,42.8 and 40.6 Gy.Median V_(5) of the lung was 15.2%,15.0%,14.8%,14.6%,V_(10) was 11.4%,10.9%,10.6%,10.1%and V_(20) was 5.0%,4.6%,4.4%,4.1%.Median dose was 4.0,3.8,3.7 and 3.5 Gy.Conclusion:Boosting the maximum dose in the target mainly influence the dose to the tumor,chest wall and the rib while its influence to the lung dose was limited.Patient-specific dosing strategy considering the adjacence between the tumor and normal tissue is recommended in clinical practice.