利用部分投影的二维CT旋转中心偏移快速校正

现有的CT重建算法都依赖于转台旋转中心的准确定位,否则会引起重建图像的伪影。目前已有的旋转中心估计方法的共同特点是利用180°或360°的投影数据。获取这些投影,需要比较长的扫描时间,占用比较多的资源。为此,在平行束扫描和扇形束扫描两种情形下,本文提出利用部分视角的投影来对转台旋转中心进行快速定位的方法。在平行束情形,利用物体空间质心与投影空间的质心的对应关系定理,由60°的投影即可准确测量出旋转中心的位置。在扇形束情形,通过将扇形束投影重排成平行束投影,仍可由扇形角再进行60°的投影准确测量出旋转中心的位置。 

Fast-correction of Rotating Center Offset with Part Views Sinogram in 2D CT

The existing CT reconstruction algorithms depend on the precise position of the center of rotation. Without the accurate positioning, artifacts will be introduced into the reconstructed image. Sinograms with 180° or 360° views are used to estimate the rotation center. These projection require a long scan time and more computing resources. In this paper, we propose two methods for correcting the rotation center offset of parallel-beam scan and fan-beam scan, both of which only use part views of the projection data. In parallel beam scan, we use the theorem relating to the mass center of the object space and the projection space, to accurately measure the location of the rotation center in the sinogram from the 60° view. In fan beam scan, we realign the fan projection to the parallel projection, rotation center can still be measured accurately in the sonogram from the fan angle plus 60° view.