摘要
目的探讨在相同扫描条件下,背景密度的变化对模拟结节CT值测量的影响。方法建立实验模型:选取直径10cm薄壁聚乙烯材质圆柱形容器作为实验模型的主体,将0.5%的复方泛影葡胺溶液(CT值约50HU),分装入橡胶囊内,制作成直径为1.5cm的球体胶囊,模拟结节灶,固定于容器中心,制成实验模型。选取空气、油脂、蒸馏水及不同密度的复方泛影葡胺溶液等15种物质,依次充填入容器内,作为结节灶的背景介质,每更换一种介质进行一次螺旋扫描。扫描参数:电压120kV,电流50mA,FOV 15cm,准直0.75mm,标准算法重建,重建函数:B40fmedium,重建层厚2mm。采用统一标准在sygo工作站处理图像并测量各组背景介质中结节灶的CT值,用SPSS17.0软件进行统计学处理。结果-1 000～20HU密度背景下,结节灶的测量CT值随背景密度增高而减小,P<0.05;在40～120HU密度背景下,结节灶的测量CT值无显著差异,P>0.05;140～430HU密度背景下,结节灶的测量CT值随背景密度增高而增高,P<0.05。结论不同密度的均质背景对小结节灶的CT值测量具有一定的影响作用;背景密度与结节灶密度差异越大,结节灶测得的CT值越偏高。
Objective To research the effect of background factors on the CT numbers of simulated nodules under the same scanning parameter. Methods A 10 cm diameter cylindrical thin wall plastic container was taken as the phantom. The simulated spherical nodules made with 0.5% compound meglumine diatrizoate sealed with rubber membrane, whose diameters were about 1.5 cm, were set at the center of the phantom. 15 different density materials were selected as the nodule＇s background medium. Helical scan of the phantom was performed under the same scanning parameter. The scan was repeated and the background medium was changed each time. CT numbers were measured on the workstation with a unified standard and analyzed with SPSS 17.0 Statistical software. Results The CT numbers of the same nodules are similar in 40-120 HU density background （ P 〉0.05）. In -1 000-20 HU density background, the higher the background density is, the lower the nodule＇s CT numbers are （ P d0.05）, while in 140-430 HU density background, the higher the background density is, the higher the nodule＇s CT numbers are （ P d0.05）. Conclusion There are certain effects on the measurement of nodulCs CT numbers in different homogeneous density background medium. The bigger the density difference between the nodule＇s and its background, the higher the measurement of the nodule＇s CT numbers are.
出处
《医学影像学杂志》
2013年第3期465-468,共4页
Journal of Medical Imaging
