基于图像变形配准的肺癌自适应放疗剂量学研究

Dosimetric study of adaptive radiation therapy based on deformable image registration for lung cancer

目的:应用图像配准技术实现肺癌自适应放疗中剂量的累加,并评价放疗计划中靶区、正常组织和危及器官相应的剂量学改变。方法:选取9例接受自适应调强放射治疗的肺癌患者,这些患者在经过20次分次治疗后,重新采集CT图像,运用变形图像配准技术将2次CT图像进行剂量累加,得到累加剂量以及相关计量学参数,然后比较自适应放疗及常规的调强放射的剂量学差异。结果:经自适应放疗,大体肿瘤体积(GTV)体积相对于放疗前平均缩小53.2%,靶区肿瘤受照剂量相对于常规调强放疗计划平均提高0.41 Gy;肺组织V_(20)、V_(30)分别平均降低2.17%、3.32%;心脏V_(30)平均降低1.14%,V_(40)降低2.98%;脊髓最大受照剂量降低1.21 Gy。结论:肺癌放疗过程中,自适应放疗相对于常规调强放疗能提高靶区受照剂量,有效减少周围正常组织剂量,降低放疗副作用的发生。

Objective To achieve the accumulative dose of adaptive radiation therapy （ART） for lung cancer by using deformable image registration technique; to evaluate the dosimetric differences of target volume, normal tissue and organs at risk. Methods Nine lung cancer patients treated with ART were selected. After 20 fraetionated treatments, CT images were collected again. The original CT images and collected CT images were accumulated by using deformable image registration technique to obtain accumulative dose and related metrology parameters. And the dosimetric differences between ART and conventional intensity-modulated radiotherapy （IMRT） were compared. Results Compared with the volume before ART, the gross tumor volume was reduced by an average of 53.2%. Compared with conventional IMRT, the dose of target volume was increased by 0.41 Gy; the V20 and V30 of lung tissue were respectively decreased by averages of 2.17% and 3.32%; the V30 and V40 of heart were respectively decreased by averages of 1.14% and 2.98%; the maximum dose of spinal cord was decreased by 1.21 Gy. Condusion Compared with conventional IMRT, ART for lung cancer improves the dose of target volume, effectively decreases the dose of surrounding normal tissue, and reduces the radiation side effect.