C型臂锥形束CT成像偏离正中心点对图像噪声及变形程度的影响

发布时间：2018-06-05 02:10

本文选题：体层摄影技术 + X线计算机　；参考：《中国医学影像技术》2014年07期

【摘要】：目的观察C型臂锥形束CT成像偏离正中心点对图像噪声及影像变形程度的影响。方法采用Siemens Axiom Artis Zee血管机,DynaCT成像模式,设置成像时间为20s。①标准水模实验:对CT标准质控水模进行成像,选择水模图像密度均匀且伪影少的20个层面,分别测量前(A)、后(P)、左(L)、右(R)方向上正中心点和偏离正中心点2、4、6、8、10cm位置图像的X线衰减值及其标准差;以X线衰减值标准差为图像噪声,采用单因素方差分析法进行客观评价。②钢球模型实验:分别将直径为17.20mm钢球分别放于前后(A-P)、左右(L-R)及头足(H-F)方向正中心和偏离正中心2、4、6cm处进行成像;在Leonardo工作站上重建三维图像,测量每个钢球在A-P、L-R及H-F方向上的直径,计算在各方向上钢球影像的变形度。结果 C型臂锥形束CT成像中,在A、P、L、R各方向上,随偏离正中心点距离增大,噪声值逐渐减小(P均0.05)。在A、P、L、R、H、F方向上,随着偏离正中心点距离增加,不同方向钢球直径变形度有所增加;H-F方向上偏离正中心点时,钢球H、F方向直径变形度相对较小(变形度绝对值均0.2%);P方向上,以A-P方向偏离正中心点时,钢球直径变形度最小。结论 C型臂锥形束CT成像中,在偏离正中心点的各个方向的不同位置,图像噪声和影像变形程度均存在一定差异。
[Abstract]:Objective to observe the effect of C-arm conical beam CT imaging deviation on image noise and image deformation. Methods the imaging mode of Siemens Axiom Artis Zee vascular machine and dyna CT was used. The imaging time was set as 20s.1 standard water model experiment. The CT standard quality control water model was imaged, and 20 layers of water model image with uniform density and less artifacts were selected. The radiographic attenuation values and their standard deviations of the positive center point and the deviation point 2 / 4 / 6 / 810 cm position image in the direction of front and rear Pian, left Ln and right side are measured respectively, and the standard deviation of X ray attenuation value is taken as image noise, and the radiographic attenuation value and standard deviation of X ray attenuation value are taken as the noise of the image, and the standard deviation of the X ray attenuation value is taken as the image noise. The objective evaluation of steel ball model was carried out by single factor variance analysis. The diameter of 17.20mm steel ball was placed in the positive center of the front and back, the left and right side of the steel ball, and the H-F of the head and foot, respectively. The imaging was carried out at the point of 2cm and 6cm from the center of the steel ball. Three-dimensional image was reconstructed on Leonardo workstation, and the diameter of each steel ball in A-PnL-R and H-F directions was measured, and the deformation degree of steel ball image in each direction was calculated. Results in C-arm conical beam CT imaging, the noise value decreased gradually with the increase of distance from the positive center point. With the increase of distance from the positive center point, the deformation degree of steel ball diameter in different directions increases with the increase of distance away from the positive center point, and the deformation degree of steel ball H F direction deviates from the positive center point in H-F direction, the deformation degree of steel ball H F direction is relatively small (the absolute values of deformation degree are 0.2 / P direction, respectively), and when the distance from the positive center point increases, the steel ball diameter deformation degree in H-F direction is smaller than that in H-F direction. When A-P direction deviates from the positive center point, the deformation degree of steel ball diameter is minimum. Conclusion in the conical beam CT imaging of C-arm, there are some differences in image noise and image deformation in different positions deviating from the positive central point.
【作者单位】：重庆医科大学附属第一医院放射科;
【基金】：重庆市卫生局科研基金重点项目(2013-1-003) 国家临床重点专科建设项目基金(国卫办[2013]544号)
【分类号】：R814.42;TP391.41

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