锥束CT的分区短扫描FDK重建算法

Segmentation short scan FDK reconstruction algorithm for cone-beam CT

圆轨道锥束CT(computed tomography)重建中,随着锥角增大,锥角伪影和数据缺失伪影越来越严重,影响FDK算法(由Feldkamp-Davis-Kress名字命名)重建区域的大小和图像质量。本文分析了短扫描FDK算法(short scanFDK,SS-FDK)重建时的数据完整性,提出了根据重建切片高度自适应地将重建切片分成若干区域,对每个区域采用SS-FDK算法进行重建的分区短扫描FDK重建算法。理论分析及试验仿真表明,该方法虽然计算复杂度有所增加,但充分利用了锥束CT投影数据,较大地增大了重建区域,完全重建区域高度达到扫描高度的1-sin2δ倍(δ为射线源半张角),且重建精度和图像质量与FDK算法相当。

The data loss and cone-beam angle artifacts increase with cone angle in circular trajectory cone-beam computed tomography （CT）. This limits the reconstruction coverage and image quality of the FDK （Feldkamp-Davis-Kress） algorithm. This paper analyzed the data completeness of the short scan FDK （SS-FDK） algorithm and presented a segmentation short scan FDK reconstruction algorithm. In the algorithm, the reconstruction slice was adaptively divided into several sub-regions according to the slice height and then the SS-FDK algorithm was used to reconstruct each sub-region. Theoretical analyses and simulations show that, although the reconstruction complexity is increased, the reconstruction region height is enlarged to 1 -- sin^2δ times of the scan height （δ, half fan angle of the source）, and the image quality and accuracy is at least comparable to that of the FDK algorithm.