Department of Radiology, Stanford University, Stanford, California 94305, USA.
Med Phys. 2010 Oct;37(10):5351-60. doi: 10.1118/1.3484058.
This article presents a new reconstruction method for 3D imaging using a multiple 360 degrees circular orbit cone beam CT system, specifically a way to combine 3D volumes reconstructed with each orbit. The main goal is to improve the noise performance in the combined image while avoiding cone beam artifacts.
The cone beam projection data of each orbit are reconstructed using the FDK algorithm. When at least a portion of the total volume can be reconstructed by more than one source, the proposed combination method combines these overlap regions using weighted averaging in frequency space. The local exactness and the noise performance of the combination method were tested with computer simulations of a Defrise phantom, a FORBILD head phantom, and uniform noise in the raw data.
A noiseless simulation showed that the local exactness of the reconstructed volume from the source with the smallest tilt angle was preserved in the combined image. A noise simulation demonstrated that the combination method improved the noise performance compared to a single orbit reconstruction.
In CT systems which have overlap volumes that can be reconstructed with data from more than one orbit and in which the spatial frequency content of each reconstruction can be calculated, the proposed method offers improved noise performance while keeping the local exactness of data from the source with the smallest tilt angle.
本文提出了一种使用多 360 度圆形轨道锥形束 CT 系统进行 3D 成像的新重建方法，特别是一种结合每个轨道重建的 3D 体积的方法。主要目标是提高组合图像中的噪声性能，同时避免锥形束伪影。
使用 FDK 算法重建每个轨道的锥形束投影数据。当至少一部分总容积可以由多个源重建时，所提出的组合方法使用频率空间中的加权平均来组合这些重叠区域。使用 Defrise 体模、FORBILD 头部体模和原始数据中的均匀噪声的计算机模拟测试了组合方法的局部精确性和噪声性能。
无噪声模拟表明，在组合图像中保留了来自最小倾斜角源的重建体积的局部精确性。噪声模拟表明，与单个轨道重建相比，组合方法提高了噪声性能。
在具有可以用来自多个轨道的数据重建的重叠体积的 CT 系统中，并且可以计算每个重建的空间频率内容的情况下，该方法提供了改进的噪声性能，同时保持了来自最小倾斜角源的数据的局部精确性。
