Department of Engineering Physics, Tsinghua University, Beijing, China.
Med Phys. 2024 Jun;51(6):4121-4132. doi: 10.1002/mp.16988. Epub 2024 Mar 7.
Ring artifact is a common problem in Computed Tomography (CT), which can lead to inaccurate diagnoses and treatment plans. It can be caused by various factors such as detector imperfections, anti-scatter grids, or other nonuniform filters placed in the x-ray beam. Physics-based corrections for these x-ray source and detector non-uniformity, in general cannot completely get rid of the ring artifacts. Therefore, there is a need for a robust method that can effectively remove ring artifacts in the image domain while preserving details.
This study aims to develop an effective method for removing ring artifacts from reconstructed CT images.
The proposed method starts by converting the reconstructed CT image containing ring artifacts into polar coordinates, thereby transforming these artifacts into stripes. Relative Total Variation is used to extract the image's overall structural information. For the efficient restoration of intricate details, we introduce Directional Gradient Domain Optimization (DGDO) and design objective functions that make use of both the image's gradient and its overall structure. Subsequently, we present an efficient analytical algorithm to minimize these objective functions. The image obtained through DGDO is then transformed back into Cartesian coordinates, finalizing the ring artifact correction process.
Through a series of synthetic and real-world experiments, we have effectively demonstrated the prowess of our proposed method in the correction of ring artifacts while preserving intricate details in reconstructed CT images. In a direct comparison, our method has exhibited superior visual quality compared to several previous approaches. These results underscore the remarkable potential of our approach for enhancing the overall quality and clinical utility of CT imaging.
The proposed method offers an analytical solution for removing ring artifacts from CT images while preserving details. As ring artifacts are a common problem in CT imaging, this method has high practical value in the medical field. The proposed method can improve image quality and reduce the difficulty of disease diagnosis, thereby contributing to better patient care.
环形伪影是计算机断层扫描（CT）中的一个常见问题，可能导致诊断和治疗计划不准确。它可能由各种因素引起，例如探测器不完善、散射栅格或放置在 X 射线束中的其他非均匀滤波器。基于物理的这些 X 射线源和探测器非均匀性的校正通常无法完全消除环形伪影。因此，需要一种强大的方法，可以有效地去除图像域中的环形伪影，同时保留细节。
本研究旨在开发一种从重建的 CT 图像中去除环形伪影的有效方法。
该方法首先将包含环形伪影的重建 CT 图像转换为极坐标，从而将这些伪影转换为条纹。相对全变差用于提取图像的整体结构信息。为了有效恢复复杂的细节，我们引入了方向梯度域优化（DGDO），并设计了利用图像梯度及其整体结构的目标函数。然后，我们提出了一种有效的分析算法来最小化这些目标函数。通过 DGDO 获得的图像然后转换回笛卡尔坐标，完成环形伪影校正过程。
通过一系列合成和真实世界的实验，我们有效地证明了我们提出的方法在纠正环形伪影的同时保留重建 CT 图像中复杂细节的能力。在直接比较中，我们的方法在视觉质量方面明显优于几种以前的方法。这些结果突出了我们的方法在增强 CT 成像整体质量和临床实用性方面的巨大潜力。
该方法提供了一种从 CT 图像中去除环形伪影同时保留细节的解析解决方案。由于环形伪影是 CT 成像中的一个常见问题，因此该方法在医学领域具有很高的实用价值。该方法可以提高图像质量，降低疾病诊断的难度，从而改善患者的护理。
