基于4DCT和形变配准技术评估呼吸运动对肺癌立体定向放射治疗过程中剂量的影响  

Dose variation caused by respiratory motion on SBRT for lung tumors: an analysis based on 4DCT and deformable registration

作　　者：吴文婧[1] 李毅[2] 孙玄子 张晓智[2] 孙雷焕[1] 张斌[1] 李军军[3] WU Wenjing;LI Yi;SUN Xuanzi;ZHANG Xiaozhi;SUN Leihuan;ZHANG Bin;LI Junjun(Department of Radiological Health,Xi'an Centerfor Disease Control and Prevention,Xi'an 710054,China;Department of Radiation Oncology,the First Affiliated Hospital of Xi'an Jiaotong University,Xi'an 710061,China;Department of Medical Imaging,the First Affiliated Hospital of Xi'an Jiaotong University,Xi'an 710061,China)

机构地区：[1]西安市疾病预防控制中心放射卫生科,陕西西安710054 [2]西安交通大学第一附属医院肿瘤放疗科,陕西西安710061 [3]西安交通大学第一附属医院医学影像科,陕西西安710061

出　　处：《中国医学物理学杂志》2019年第12期1406-1410,共5页Chinese Journal of Medical Physics

基　　金：西安交通大学第一附属医院院基金(2018MS-25)

摘　　要：目的:探讨肺下叶肿瘤患者立体定向放射治疗(SBRT)治疗时,呼吸运动对肿瘤和正常器官受量的影响。方法:选取14例肺下叶肿瘤患者,均行平扫CT和四维CT(4DCT)扫描定位,获得平扫及10个呼吸时相的序列图像,同时记录患者放疗时的呼吸曲线,并得到各呼吸时相维持时间占比。利用MIM工作站勾画肿瘤和正常器官,基于平扫CT制定放疗计划,将3DCT计划移植到各呼吸时相的序列图像中并计算剂量,按照时间占比叠加各个时相的剂量。结果:比较平扫CT计划剂量分布和叠加剂量分布,得出相比平扫CT计划剂量。叠加剂量中,PTV平均剂量、患侧肺V20、患侧肺平均剂量、健侧肺平均剂量和全肺平均剂量的4D加权叠加均小于3D剂量,分别减小了2.37%、5.08%、5.19%、3.61%和3.46%,差异均有统计学意义(P<0.05)。结论:患者的呼吸运动导致肿瘤和肺受量的降低,但在较小的变化范围内。利用4DCT和形变配准技术,引入患者各呼吸时相维持时间占比的因素,可更合理评估呼吸运动对肺下叶肿瘤SBRT放射治疗过程中剂量的影响。Objective To discuss the effects of respiration motions on the doses to tumors and organs-at-risk in patients receiving stereotactic body radiotherapy for lung tumors in the lower lobe.Methods Fourteen patients with lung tumors in the lower lobe underwent plain CT scans and four-dimensional CT(4DCT)scans to acquire plain scanning image and sequence images of 10 respiratory phases.The percentage of time intervals of each respiratory phase in a whole respiratory motion was calculated from respiratory motion curves recorded during radiotherapy.MIM workstation was used to delineate tumors and organs-at-risks.Treatment plan was designed based on plain CT,and then 3DCT plan was ported to sequence images of each respiratory phase for dose calculation by accumulating doses based on the percentages of time intervals of each respiratory phase.Results The 4D weighted dose accumulations of the mean dose of planning target volume,the V20 and mean dose of ipsilateral lung,the mean dose of contralateral lung and the mean dose of lungs were decreased by 2.37%,5.08%,5.19%,3.61%and 3.46%,respectively,compared with 3D planned doses,with statistical differences(P<0.05).Conclusion The respiratory motions of patients result in decreased doses to tumors and lungs,but the variation is within a small range.The dose variation caused by respiratory motion on SBRT for lung tumors in the lower lobe can be more accurately evaluated by utilizing 4DCT and deformable registration and introducing the percentages of time intervals of each respiratory phase.

关 键 词：肺肿瘤 四维CT 形变配准技术 呼吸曲线 立体定向放射治疗 剂量 

分 类 号：R811.1[医药卫生—放射医学] R734.2[医药卫生—临床医学]