Evaluation of the spatial resolution characteristics of a cone-beam breast CT scanner
Evaluation of the spatial resolution characteristics of a cone-beam breast CT scanner
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DOI：
10.1118/1.2400830
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发表时间：
2007-01-01
期刊：
影响因子：
3.8
通讯作者：
Huang, Shih-Ying
中科院分区：
文献类型：
--
作者：
Kwan, Alexander L. C.;Boone, John M.;Huang, Shih-Ying
本研究的目的是检查一个原型垂形几何锥形束乳房计算机断层扫描（CT）系统的空间分辨率。重建图像在冠状（x和y）平面上的调制传递函数（mtf）作为锥角、到旋转轴的径向距离、重建矩阵的大小、所使用的反投影滤波器以及重建所需的投影数的函数进行计算。结果表明，重构矩阵的锥角和尺寸对MTF的影响最小，而MTF沿旋转轴呈径向退化（从距旋转轴2.6 mm处的0.76下降到距旋转轴76.9 mm处的0.37,f=0.5 mm(-1)）。Ramp重建滤波器相对于Shepp-Logan滤波器增加了旋转轴附近的MTF，而投影数从500增加到1000则增加了重建图像周边附近的MTF。同时评估z方向（前后方向）的MTF。与冠状面MTF相比，z方向MTF值往往更高（在f =0.5 mm（-1）处为0.85），并且在整个冠状面方向上趋于非常恒定。结果表明，通过优化各种扫描和重建参数，可以提高原型乳腺CT系统的MTF。(c) 2007年美国医学物理学家协会。
The purpose of this study was to examine the spatial resolution of a prototype pendant-geometry cone-beam breast computed tomography (CT) system. Modulation transfer functions (MTFs) of the reconstructed image in the coronal (x and y) plane were computed as a function of the cone angle, the radial distance from the axis of rotation, the size of the reconstruction matrix, the back-projection filter used, and the number of projections acquired for the reconstruction. The results show that the cone angle and size of the reconstruction matrix have minimal impact on the MTF, while the MTF degraded radially from the axis of rotation (from 0.76 at 2.6 mm from axis of rotation down to 0.37 at 76.9 mm from axis of rotation at f=0.5 mm(-1)). The Ramp reconstruction filter increases the MTF near the axis of rotation relative to the Shepp-Logan filter, while an increase in the number of projections from 500 to 1000 increased the MTF near the periphery of the reconstructed image. The MTF in the z direction (anterior-posterior direction) was also evaluated. The z-direction MTF values tend to be higher when compared to the coronal MTF (0.85 at f =0.5 mm(-1)), and tend to be very constant throughout the coronal plane direction. The results suggest that an increase in the MTF for the prototype breast CT system is possible by optimizing various scanning and reconstruction parameters. (c) 2007 American Association of Physicists in Medicine.