目的:肺癌靶区运动是影响放射治疗效果的重要因素之一,目前有很多方法试图解决这一问题,如4D-CT,呼吸门控,慢CT,等,但各有缺陷,都不理想.本文使用模体研究常规CT定位和PET/CT定位并比较.材料和方法:将不同形状CT模体/灌注F18-FDG模体,固定于呼吸运动平台上,使用Simens Biograph64同机PET-CT不同条件扫描(64排CT和39环PET),瓦里安Eclipse治疗计划系统三维重建,勾画并比较体积差异.结果:快速CT扫描运动模体,最大丢失体积达-50.8%(36.2 cm3);PET图像同物体运动轨迹体积比较最大差异-16.3%,且没有出现变形现象.PET图像所有体积小于真实运动轨迹体积,这同显示条件有关系.结论:快速CT只能随机捕捉运动物体部分体积并存在变形情况,不适合应用于活动肿瘤(肺癌)放射治疗计划定位;PET-CT能够较稳定地反映运动物体运动轨迹,且没有图像变形,能较好代表内靶区,并且操作相对简单,病人容易耐受.%Objective: The moving lung cancer is difficult to define in the process of treatment planning. At present there are many methods to be employed to solve this problem, such as 4D-CT,gating and slow CT ,but they are far more perfect. In this study ,we try to investigate whether PET-CT can predict the internal target volume by imaging a moving phantom. Methods and Materials: The CT phantom and a ball filled with F18-FDG were immobilized on the Respiratory gating platform respectively and imaged by the Simens Biograph64 true point PET-CT. All the images were transferred to the Varian Eclipse treatment planning system. Volumes were contoured and compared with all the true moving volumes. Results: Fast CT scanning moving phantom volumes lost 50.8％(36.2 cm3) maximally while PET image volumes lost 16.3％ maximally. Conclusions: Fast CT image can only predict part true moving volume and its images are not reasonable to be used in the moving target contouring .PET-CT images can predict the moving phantom locus comprehensively and can improve the target contouring for moving tumours.
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