Guan H, Gordon R, Zhu Y
Department of Radiation Oncology, St Jude Children's Research Hospital, Memphis, TN 38105, USA.
Phys Med Biol. 1998 Aug;43(8):2413-21. doi: 10.1088/0031-9155/43/8/032.
We separately applied three different projection access orders (the multilevel scheme (MLS), the sequence access scheme (SAS) and the random permutation scheme (RPS)) to the algebraic reconstruction technique (ART) in an attempt to improve low-contrast object detection in computed tomography (CT). We used both simulated (from various numbers of projections of low-contrast and contrast detail phantoms) and actual data (from megavoltage portal CT) during our study. When coupled with ART, SAS and RPS led to poor low-contrast detection and required multiple iterations for convergence. In contrast, one-iteration MLS yielded the most uniform reconstructions with the highest contrast-to-noise ratios. Therefore, MLS-ART provides the highest dose efficiency of all current reconstruction techniques for imaging low-contrast objects from a small number of projections.
我们分别将三种不同的投影访问顺序（多级方案（MLS）、序列访问方案（SAS）和随机排列方案（RPS））应用于代数重建技术（ART），以尝试改善计算机断层扫描（CT）中的低对比度物体检测。在我们的研究中，我们使用了模拟数据（来自低对比度和对比度细节体模的各种数量投影）和实际数据（来自兆伏级门静脉CT）。当与ART结合使用时，SAS和RPS导致低对比度检测效果不佳，并且需要多次迭代才能收敛。相比之下，单次迭代的MLS产生了最均匀的重建结果，对比度噪声比最高。因此，对于从少量投影成像低对比度物体，MLS-ART在所有当前重建技术中提供了最高的剂量效率。
