摘要目的 探讨平静EI和EE时相融合图像确定肝癌个体化靶区几何学差异和可行性及临床意义.方法 2012-2013年本院18例肝癌患者分别在相同体位和扫描范围下行自由呼吸(FB)、平静EI、EE状态的增强3DCT扫描.分别在上述图像上勾画GTV、CTV及OAR.在FB图像上勾画GTVFB,各向外扩10 mm形成CTVFB,CTVFB头脚外扩20 mm、左右前后外扩10 mm形成PTVFB.分别在平静EI、EE图像上勾画GTVEI、GTVEE,并以平静EE为基准进行图像配准融合形成GTVEI+EI,各向外扩10 mm形成CTVEI+EE,头脚方向外扩10 mm、左右前后外扩5 mm形成PTVEI+EE.利用Pinnacle 3 v8.0mTPS为每例患者设计两套3DCRT计划,比较两套计划中CTVFB和CTVEI+EE、PTVFB和PTVEI+EE的大小、包含度(DI)及匹配指数(MI)和中心位移.结果 18例患者CTVFB、CTVEI+EE平均体积分别为(149.00± 87.54)、(188.17± 125.72) cm3(P=0.014);PTVFB、PTVEI+EE的平均体积分别为(276.68± 146.41)、(253.66± 117.35) cm3(P=0.080);CTVFB被CTVE+EI的DI为(99.83±0.09)％,PTVFB被PTVE+EI的DI为(84.55±8.45)％;反之,CTVE+EI被CTVFB的DI为(80.83± 12.31)％,PTVE+EI被PTVFB的DI为(99.78±0.08)％.CTVE+EI与CTVFB、PTVE+ET与PTVFB的MI分别为0.83±0.07、0.87±0.03.相对于CTVFB中心点坐标,CTVEI+EE在x、y、z轴位移分别为(0.55±1.07)、(0.76±3.02)、(-0.26±1.98)cm (P=0.432、0.971、0.587).结论 利用3DCT平静EI、EE图像进行肝癌靶区勾画和融合有可能避免呼吸运动造成靶区漏照,从而为提高靶区剂量及肝癌放疗疗效提供可能.

abstractsObjective To use the fusion image of the end-inhalation holding (EIH) phase and endexhalation holding (EEH) phase to define the target volume of individual patient with liver cancer,and to evaluate the target geometry,feasibility,and clinical significance of the technology.Methods Eighteen patients with liver caucer who were treated in our hospital from 2012 to 2013 were enrolled as subjects.With the same posture and scan range,all patients underwent contrast-enhanced three-dimensional computed tomography (3DCT) scans in the phases of free breathing (FB),EIH,and EEH.Gross tumor volume (GTV),clinical target volume (CTV),and organ of risk (OAR) were delineated on the above images.CTVFB was defined as GTV on the FB phase image (GTVFB) plus a margin of 10 mm,while planning target volume (PTVFB) was defined as CTVFB plus a margin of 10 mm in the right-left and anterior-posterior directions and a margin of 20 mm in the superior-inferior direction.GTVEI and GTVEE were defined as GTV on the EIH and EEH images,respectively.Based on the EEH images,the registered EEH and EIH images were fused to form GTVEI+EI.CTVEI+EE was defined as GTVEI+EI plus a margin of 10 mm,while PTVEI+EE was defined as CTVEI+EE plus a margin of 5 mm in the right-left and anterior-posterior directions and a margin of 10 mm in the superior-inferior direction.The Pinnacle3 v8.0m treatment planning system was used to design two 3D conformal radiotherapy plans for each patient.The volume,degree of inclusion (DI),matching index (MI),and central displacement of CTVFB and CTVEI+EE,as well as PTVFB and PTVEI+EE,were compared between the two plans.Results In the 18 patients,the mean CTVFB was significantly smaller than the mean CTVEI+EE(149.00±87.54 cm3 vs.188.17± 125.72 cm3,P=0.014);there was no significant difference between the mean PTVFB and PTVEI+EE (276.68± 146.41 cm3 vs.253.66± 117.35 cm3,P=0.080).DI of CTVFB to CTVEI+EF,PTVFB to PTVEI+EE,CTVEI+EE to CTVFB,and PTVEI+EE to PTVFB were (99.83±0.09)％,(84.55±8.45) ％,(80.83± 12.31) ％,and (99.78±0.08) ％,respectively.MI of CTVEI+EE to CTVFB and PTVEI+EE to PTVFB were 0.83± 0.07 and 0.87± 0.03,respectively.The central displacements of CTVEI+EE from CTVFB in x,y,and z axes were 0.55± 1.07 cm,0.76±3.02 cm,and-0.26± 1.98 cm,respectively (P =0.432,0.971,0.587).Conclusions In the treatment of liver cancer,the target volume delineation and image fusion using 3DCT images in EIH and EEH phases may avoid target omission due to respiratory movement,making it possible to increase radiation dose to target volume and improve the efficacy of radiotherapy.