Joint Department of Biomedical Engineering, North Carolina State University and The University of North Carolina at Chapel Hill, Campus Box 7115, Raleigh, NC 27695-7115, USA.
Phys Med Biol. 2012 Mar 7;57(5):1309-23. doi: 10.1088/0031-9155/57/5/1309. Epub 2012 Feb 17.
Energy-discriminated x-ray computed tomography (CT) data were projected onto a set of basis functions to suppress the noise in filtered back-projection (FBP) reconstructions. The x-ray CT data were acquired using a novel x-ray system which incorporated a single-pixel photon-counting x-ray detector to measure the x-ray spectrum for each projection ray. A matrix of the spectral response of different materials was decomposed using eigenvalue decomposition to form the basis functions. Projection of FBP onto basis functions created a de facto image segmentation of multiple contrast agents. Final reconstructions showed significant noise suppression while preserving important energy-axis data. The noise suppression was demonstrated by a marked improvement in the signal-to-noise ratio (SNR) along the energy axis for multiple regions of interest in the reconstructed images. Basis functions used on a more coarsely sampled energy axis still showed an improved SNR. We conclude that the noise-resolution trade off along the energy axis was significantly improved using the eigenvalue decomposition basis functions.
能量分辨 X 射线计算机断层扫描（CT）数据被投影到一组基函数上，以抑制滤波反投影（FBP）重建中的噪声。X 射线 CT 数据是使用一种新型 X 射线系统采集的，该系统结合了单像素光子计数 X 射线探测器，用于测量每个投影射线的 X 射线光谱。使用特征值分解对不同材料的光谱响应矩阵进行分解，形成基函数。将 FBP 投影到基函数上，创建了多个对比剂的实际图像分割。最终的重建结果显示出显著的噪声抑制，同时保留了重要的能量轴数据。通过在重建图像中多个感兴趣区域的能量轴上信噪比（SNR）的显著提高，证明了噪声抑制效果。在更粗糙的能量轴上使用的基函数仍然显示出 SNR 的提高。我们得出结论，使用特征值分解基函数显著改善了沿能量轴的噪声分辨率权衡。
