Institute of Nanotechnology-CNR, Rome Unit, Rome, Italy.
Phys Med Biol. 2018 Feb 12;63(4):045007. doi: 10.1088/1361-6560/aaa706.
The suppression of ring artifacts in x-ray computed tomography (CT) is a required step in practical applications; it can be addressed by introducing refined digital low pass filters within the reconstruction process. However, these filters may introduce additional ringing artifacts when simultaneously imaging pure phase objects and elements having a non-negligible absorption coefficient. Ringing originates at sharp interfaces, due to the truncation of spatial high frequencies, and severely affects qualitative and quantitative analysis of the reconstructed slices. In this work, we discuss the causes of ringing artifacts, and present a general compensation procedure to account for it. The proposed procedure has been tested with CT datasets of the mouse central nervous system acquired at different synchrotron radiation facilities. The results demonstrate that the proposed method compensates for ringing artifacts induced by low pass ring removal filters. The effectiveness of the ring suppression filters is not altered; the proposed method can thus be considered as a framework to improve the ring removal step, regardless of the specific filter adopted or the imaged sample.
在 X 射线计算机断层扫描（CT）中抑制环形伪影是实际应用中的必要步骤；可以通过在重建过程中引入精细的数字低通滤波器来解决这个问题。然而，当同时对纯相位物体和具有不可忽略吸收系数的元素进行成像时，这些滤波器可能会引入额外的环形伪影。环形伪影源于空间高频的截断，出现在锐利的界面处，严重影响了重建切片的定性和定量分析。在这项工作中，我们讨论了环形伪影的原因，并提出了一种通用的补偿程序来解决这个问题。所提出的方法已经在不同同步辐射设施获取的小鼠中枢神经系统的 CT 数据集上进行了测试。结果表明，所提出的方法可以补偿由低通环形去除滤波器引起的环形伪影。环形抑制滤波器的有效性不会改变；因此，无论采用特定的滤波器或成像样本如何，该方法都可以被视为改进环形去除步骤的框架。
