Yu Lifeng, Zou Yu, Sidky Emil Y, Pelizzari Charles A, Munro Peter, Pan Xiaochuan
Department of Radiology, The University of Chicago, Chicago, IL 60637, USA.
IEEE Trans Med Imaging. 2006 Jul;25(7):869-81. doi: 10.1109/tmi.2006.872329.
The circular scanning trajectory is one of the most widely adopted data-acquisition configurations in computed tomography (CT). The Feldkamp, Davis, Kress (FDK) algorithm and its various modifications have been developed for reconstructing approximately three-dimensional images from circular cone-beam data. When data contain transverse truncations, however, these algorithms may reconstruct images with significant truncation artifacts. It is of practical significance to develop algorithms that can reconstruct region-of-interest (ROI) images from truncated circular cone-beam data that are free of truncation artifacts and that have an accuracy comparable to that obtained from nontruncated cone-beam data. In this work, we have investigated and developed a backprojection-filtration (BPF)-based algorithm for ROI-image reconstruction from circular cone-beam data containing transverse truncations. Furthermore, we have developed a weighted BPF algorithm to exploit "redundant" information in data for improving image quality. In an effort to validate and evaluate the proposed BPF algorithms for circular cone-beam CT, we have performed numerical studies by using both computer-simulation data and experimental data acquired with a radiotherapy cone-beam CT system. Quantitative results in these studies demonstrate that the proposed BPF algorithms for circular cone-beam CT can reconstruct ROI images free of truncation artifacts.
圆形扫描轨迹是计算机断层扫描（CT）中应用最为广泛的数据采集配置之一。费尔德坎普、戴维斯、克雷斯（FDK）算法及其各种改进算法已被开发出来，用于从圆形锥束数据重建近似三维图像。然而，当数据包含横向截断时，这些算法可能会重建出带有明显截断伪影的图像。开发能够从截断的圆形锥束数据重建出无截断伪影且精度与从无截断锥束数据获得的精度相当的感兴趣区域（ROI）图像的算法具有实际意义。在这项工作中，我们研究并开发了一种基于反投影滤波（BPF）的算法，用于从包含横向截断的圆形锥束数据重建ROI图像。此外，我们还开发了一种加权BPF算法，以利用数据中的“冗余”信息来提高图像质量。为了验证和评估所提出的用于圆形锥束CT的BPF算法，我们使用计算机模拟数据和通过放射治疗锥束CT系统获取的实验数据进行了数值研究。这些研究中的定量结果表明，所提出的用于圆形锥束CT的BPF算法能够重建出无截断伪影的ROI图像。
