基于四维CT探讨腹部加压对周围型肺部肿瘤立体定向放疗靶区位移及外扩边界的影响  

boundary of peripheral pulmonary tumors treated with stereotactic radiotherapy based on 4DCT

作　　者：戚元俊 李建彬 张英杰 邵倩 刘希军 李奉祥 王金之 李振祥 王玮 Qi Yuanjun;Li Jianbin;Zhang Yingjie;Shao Qian;Liu Xijun;Li Fengxiang;Wang Jinzhi;Li Zhenxiang;Wang Wei(Shandong First Medical University and Shandong Academy of Medical Sciences,Jinan 250117,China;Department of Radiation Oncology,Shandong Cancer Hospital and Institute,Shandong First Medical University and Shandong Academy of Medical Sciences,Jinan 250117,China)

机构地区：[1]山东第一医科大学,山东省医学科学院研究生院,济南250117 [2]山东省肿瘤防治研究院,山东省肿瘤医院放疗科,山东第一医科大学,山东省医学科学院,济南250117

出　　处：《中华放射医学与防护杂志》2021年第2期134-139,共6页Chinese Journal of Radiological Medicine and Protection

基　　金：国家自然科学基金青年基金项目(81201735);山东省重点研发计划项目(2015GSF118011)。

摘　　要：目的基于四维CT(4DCT)探讨腹部加压对周围型肺部肿瘤立体定向放疗(SBRT)靶区位移幅度、靶区体积大小及外扩边界的影响。方法前瞻性收集拟行SBRT的周围型肺部肿瘤患者,CT模拟定位时依次完成腹部加压3DCT、腹部加压4DCT(4DCT_(com))、自由呼吸4DCT(4DCT_(free))扫描,并于照射前行腹部加压锥形束CT(CBCT_(com))扫描。4DCT图像重建生成最大密度投影(MIP)图像。在上述图像上分别勾画大体肿瘤体积(GTV)并重建肿瘤内大体靶体积(IGTV),在IGTV MIP_(com)基础上分别均匀外扩5、4、3 mm构建计划靶区(PTV)MIP_(com)。按所在肺叶位置将肿瘤分为全组、肺上中叶组和肺下叶组。结果对于全组肿瘤靶区,与自由呼吸状态比较,加压使靶区中位三维运动矢量减少30.92%;对于肺上中叶和下叶靶区,加压分别使靶区中位三维运动矢量增加3.42%和减少18.80%。无论全组还是上中叶或是下叶组,肿瘤各方向位移及三维运动矢量差异均无统计学意义(P>0.05)。腹部加压使IGTV的体积显著减少,IGTV MIP_(com)、IGTV MIP_(free)和IGTV10_(com)、IGTV10_(free)中位体积分别为4.01、5.36 cm^(3)和6.59、7.65 cm^(3),差异均有统计学意义(Z=-3.45、-3.14,P<0.01)。PTV MIPcom外扩5 mm时IGTV CBCT_(com)对PTV MIP_(com)的包含度为100%,外扩4、3 mm时包含度≥95%的比例分别为100%、83.33%。结论腹部加压技术改变了患者呼吸模式,减少腹式呼吸的同时增加了胸式呼吸;IGTV MIP和IGTV10的体积减小,为SBRT患者PTV的缩小创造了条件;临床上采用腹部加压技术实施SBRT时基于4DCT的IGTV外扩4 mm形成的PTV显示了临床精准放疗的趋势。Objective To investigate the effectiveness of abdominal compression in tumor motion and the target volume,and analyze the suitable margins of planning target volume(PTV)for patients treated with lung-SBRT based on 4DCT.Methods Patients diagnosed with peripheral pulmonary tumor were enrolled.The patients were divided into the whole group,upper-middle-lobe group(group A)and the lower-lobe group(group B).Each patient underwent 3DCT,4DCT with abdominal compression(4DCT_(com))and 4DCT with free breath(4DCT_(free))scans.The GTVs were delineated and IGTVs on these images.PTV MIP_(5 mm),PTV MIP_(4 mm),PTV MI_(P3 mm)were constructed with a 5,4,3 mm margin in leftright(LR),anterior-posterior(AP)directions and cranial-caudal(CC)directions.Results The median motion vector with compression reduced by 30.92%in whole group,increased by 3.42%in group A and reduced by 18.80%in group B,respectively.And there were no significant differences of TMA LR,TMAAP,TMACC and motion vector by the Wilcoxon test(P>0.05).The median sizes of IGTV MIP_(com),IGTV MIP_(free)and IGTV10_(com),IGTV10free were 4.01,5.36 cm^(3)and 6.59,7.65 cm^(3),with statistically significant difference(Z=-3.45,-3.14,P<0.01).The median ratio of DI of IGTV CBCT_(com)in PTV MIP_(5 mm),PTV MIP_(4 mm)and PTV MIP_(3 mm)≥95%was 100%,100%and 83.33%,respectively.Conclusions The patients′respiratory pattern changed with abdominal compression and abdominal compression is useful in reducing the size of IGTV MIP and IGTV10,which could reduce the target volume and protect the normal tissue.Adding a 4 mm margin to IGTV MIPcom based on 4DCT account for respiration in SBRT is a tendency for precise radiotherapy.

关 键 词：肺肿瘤 四维CT 立体定向放疗 腹部加压 锥形束CT 

分 类 号：R734.2[医药卫生—肿瘤]