Limited-angle computed tomography (CT) reconstruction problem arises in some practical applications due to restrictions in the scanning environment or CT imaging device. Some artifacts will be presented in image reconstructed by conventional analytical algorithms. Although some regularization strategies have been proposed to suppress the artifacts, such as total variation (TV) minimization, there is still distortion in some edge portions of image. Guided image filtering (GIF) has the advantage of smoothing the image as well as preserving the edge. To further improve the image quality and protect the edge of image, we propose a coupling method, that combines ${\ell }_0$ gradient minimization and GIF. An intermediate result obtained by ${\ell }_0$ gradient minimization is regarded as a guidance image of GIF, then GIF is used to filter the result reconstructed by simultaneous algebraic reconstruction technique (SART) with nonnegative constraint. It should be stressed that the guidance image is dynamically updated as the iteration process, which can transfer the edge to the filtered image. Some simulation and real data experiments are used to evaluate the proposed method. Experimental results show that our method owns some advantages in suppressing the artifacts of limited angle CT and in preserving the edge of image.

中文翻译：

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基于导引图像滤波的ℓ0梯度最小化，用于有限角度CT图像重建

由于扫描环境或CT成像设备的限制，在某些实际应用中出现了有限角度计算机断层摄影（CT）重建问题。在通过常规分析算法重建的图像中将出现一些伪像。尽管已经提出了一些规则化策略来抑制伪像，例如使总变化（TV）最小化，但是在图像的某些边缘部分仍然存在失真。引导图像过滤（GIF）的优点是使图像平滑并保留边缘。为了进一步提高图像质量并保护图像边缘，我们提出了一种结合方法${\ell }_0$渐变最小化和GIF。通过获得的中间结果${\ell }_0$梯度最小化被视为GIF的指导图像，然后使用GIF对通过非负约束的同时代数重构技术（SART）重构的结果进行滤波。应该强调的是，引导图像随着迭代过程而动态更新，这可以将边缘转移到滤波后的图像上。通过一些仿真和真实数据实验来评估该方法。实验结果表明，我们的方法在抑制有限角度CT的伪影和保留图像边缘方面具有一些优势。