基于四维CT对肺癌原发灶位移和体积变化相关性研究

目的 探讨自由呼吸状态下基于四维CT的肺癌原发灶位移及其与感兴趣器官和体表标记位移相关性,以及各呼吸时相肿瘤体积与肺脏体积变化相关性.方法 16例肺癌患者进行自由呼吸状态下四维CT模拟定位扫描.以四维CT吸气末图像为基准图像,分别勾画肿瘤、感兴趣解剖结构和体表标志,记录配准后10套图像中的三维坐标.测量和比较各时相大体肿瘤体积( GTV)和肺脏体积以及相关性,测量肿瘤、感兴趣结构及体表标记的三维方向位移并计算三维运动矢量及其相关性.结果 不同肺叶肿瘤运动范围相差较大,肺上叶为0.8～5.0 mm,肺中叶为5.7～5.9 mm,肺下叶为10.2～13.7 mm.肿瘤位移上下方向为(4.3+4.3) mm,大于前后方向(2.2±1.0) mm和左右方向(1.7+1.5) mm (x2=16.22,P=0.000).肿瘤GTV与各感兴趣结构三维运动矢量间均无相关性(r=-0.50～-0.01,P=0.058～-0.961),不同呼吸时相GTV变化与肺脏体积变化也无相关性(r=0.23,P=0.520).结论 不同肺叶肿瘤位移和肿瘤三维方向上位移差异显著,肺癌放疗时内在靶体积外扩边界应基于四维CT测定个体化确定.

A correlation study on position and volume variation of primary lung cancer during respiration by four-dimensional CT

Objective To investigate the correlation of position movement of primary tumor with interested organs and skin markers,and to investigate the correlation of volume variation of primary tumors and lungs during different respiration phases for patients with lung cancer at free breath condition scanned by four-dimensional CT (4DCT) simulation.Methods 16 patients with lung cancer were scanned at free breath condition by simulation 4DCT which connected to a respiration-monitoring system.A coordinate system was created based on image of T5 phase,gross tumor volume (GTV) and normal tissue structures of 10 phases were contoured.The three dimensional position variation of them were measured and their correlation were analyzed,and the same for the volume variation of GTV and lungs of 10 respiratory phases.Results Movement range of lung cancer in different lobe differed extinct:0.8 - 5.0 mm in upper lobe,5.7 -5.9 mm in middle lobe and 10.2 - 13.7 mm in lower lobe,respectively.Movement range of lung cancer in three dimensional direction was different:z-axis 4.3 mm ± 4.3 mm＞ y-axis 2.2 mm ± 1.0 mm ＞ x-axis 1.7 mm ± 1.5 mm ( x2 =16.22,P =0.000),respectively.There was no statistical significant correlation for movement vector of GTV and interested structures (r =-0.50 - -0.01,P =0.058 - -0.961 ),nor for volume variation of tumor and lung ( r =0.23,P =0.520 ).Conclusions Based on 4DCT,statistically significant differences of GTV centroid movement are observed at different pulmonary lobes and in three dimensional directions.So individual 4DCT measurement is necessary for definition of internal target volume margin for lung cancer.