基于对称填补方法的CT扇束短扫描重建算法

CT fan-beam short-scan reconstruction algorithm based on symmetric filling method

传统的扇束CT扫描方式通常为圆轨迹的全周扫描,在实际应用中,有时射线源与探测器旋转空间不足或者为了满足降低射线剂量、加快扫描速度等,需要采用扇束短扫描的方式。本文对圆轨迹短扫描方式下的CT重建算法进行了研究,提出了一种基于对称填补方法的短扫描重建算法,并与Parker加权重建算法进行对比和性能分析。在仿真和实际实验中,采用峰值信噪比和结构相似度系数作为评价标准对应用两种短扫描重建算法得到的重建结果进行评估。实验表明,本文介绍的两种重建方法在重建效果上均比FBP算法有所改善,对称填补重建算法比Parker加权重建算法表现更好。在针对仿真数据时,采用对称填补重建算法可减少重建结果的噪声。

The traditional scanning method of fan-beam Computed Tomography(CT)is full scan with a circular trajectory.In order to reduce the radiation dose and speed up a CT scan or solve the problems such as the limited movement range of the ray source and the detector,fan-beam short scan is used for practical applications.In this paper,the CT reconstruction algorithm with a circular-trajectory short scan mode is studied,and a short scan reconstruction method based on symmetric filling approach is proposed.Its performance is analyzed and compared with the Parker weighted reconstruction algorithm.The peak signal-to-noise ratio(PSNR)and structural similarity(SSIM)are used as evaluation metric to evaluate the reconstruction results obtained by the two short-scan reconstruction methods in both simulations and actual experiments.Experimental results demonstrate the two reconstruction methods are both better than FBP algorithm and the symmetric filling reconstruction is better than the Parker-weighted reconstruction in performance.According to the simulation study,the symmetrical filling reconstruction algorithm can suppress noise in the reconstruction.