CT螺旋扫描速度对肺部不同部位肿瘤靶区勾画的影响

Impacts of CT Spiral Scanning Velocity on the Outlining of Tumor Target Area in Different Parts of the Lung

目的分析不同CT螺旋扫描速度在放射治疗肺部不同部位肿瘤定位时对靶区勾画的影响。方法对10例位于肺上1/2和肺下1/2部位的原发或转移性肺部肿瘤分别行快速螺旋扫描和慢速扫描,通过先后序贯同一体位螺旋快速扫描和慢速扫描,勾画肺上1/2和肺下1/2部位大体肿瘤体积(GTV)qs、GTVss,GTVqi、GTVsi的大小及三维等中心坐标。结果位于肺上1/2部位GTVqs、GTVss的体积大小分别为10.56、11.05cm3(DSC=0.97,x2=3.37,P=0.19),等中心位移误差x、y、z轴分别为0.01、0.05、0.30cm,GTVqs对GTVss的包含度(DI)=0.98,GTVss对GTVqs的DI=0.96;位于肺下1/2部位GTVqi、GTVsi的体积大小分别为9.48、14.01cm3(DSC=0.81,x2=5.32,P=0.043),等中心误差x、y、z轴分别为0.4、0.85、1.45cm,GTVqi对GTVsi的DI=0.98,GTVsi对GTVqi的DI=0.82。结论不同扫描速度在放射治疗肺部不同部位肿瘤定位时对靶区勾画存在一定影响,尤以肺下部1/2部位的肿瘤靶区勾画影响较大,模拟定位时应考虑到扫描速度的影响。

Objective To analyze the impacts of different CT spiral scanning velocities on the outlining of tumor target area for treating tumors in different parts of the lung by radiotherapy localization. Methods Ten patients with primary or metastatic tumors respectively in the superior and inferior 1/2 parts of the lung were underwent quick spiral scanning and slow spiral scanning in sequence during free breathing. The gross tumor volume （GTV）qs and GTVss as well as the centers of inertia including the sizes of GTVqi and GTVsi and three dimensions were outlined in the superior and inferior 1/2 parts of the lung. Results In the superior 1/2 part of the lung, the volumes of GTVqs and GTVss were 10. 56 cm3 and 11. 05 cm3,respectively （DSC=0. 97,X2 =3. 37,P=0. 19）, isocenter displacement deviations of axis x, y and z were 0.01 cm, 0.05 cm and 0.30 cm, respectively, and the degree of inclusion （DI） of GTVqs to GTVss was equal to 0.98,while that of GTVss to GTVqs to 0.96. In the superior 1/2 part of the lung,the volumes of GTVqi and GTV,i were 9.48 cma and 14.01 cm3 , respectively （DSC= 0.81,X2 = 5. 32,P=0. 043） ,isocenter displacement deviations of axis x,y and z were 0.4 cm,0.85 cm and 1.45 cm,respectively, and DI of GTVqi to GTVsi was equal to 0.98, while that of GTVsi to GTVqi to 0.82. Conclusion Different scanning velocities affect the outlining of tumor target area for treating tumors in different parts of the lung by radiotherapy localization,especially in the inferior 1/2 part of the lung,so the impact of scanning velocities should be considered at the time of simulated localization.