Median prior constrained TV algorithm for sparse view low-dose CT reconstruction
Median prior constrained TV algorithm for sparse view low-dose CT reconstruction
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DOI：
10.1016/j.compbiomed.2015.03.003
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发表时间：
2015-05-01
影响因子：
7.7
通讯作者：
Gui, Zhiguo
中科院分区：
文献类型：
--
作者：
Liu, Yi;Hong Shangguan;Gui, Zhiguo
众所周知，降低X射线管电流（mAs）或管电压（kVp）并同时减少X射线视图（稀疏视图）的总数是在计算机断层摄影（CT）扫描中实现低剂量的有效手段。然而，传统的滤波反投影（FBP）的相关图像质量通常会下降，由于过多的量子噪声。尽管在降低X射线管电流的扫描方案中，通过全变分（TV）的稀疏视图CT重建算法已被证明能够在保持图像质量的同时显著降低辐射剂量，但重建图像中仍存在明显的片状伪影。在这项研究中，为了解决斑片伪影的问题，我们提出了一个中值先验约束TV正则化，通过引入一个与对象配准的辅助向量m来保持图像质量。具体而言，m的近似动作是在每次迭代中将对象体素朝向其自身的局部中值绘制，旨在通过稀疏视图投影测量来改善低剂量图像质量。随后，采用交替优化算法对关联目标函数进行优化。为了简单起见，我们将中值先验约束TV正则化称为“TV_MP”。在数字体模和临床体模上的实验结果表明，与原TV方法相比，采用适当的控制参数，该方法不仅可以保证重建图像的信噪比（SNR）更高，而且其分辨率也更高。(c)2015爱思唯尔有限公司版权所有。
It is known that lowering the X-ray tube current (mAs) or tube voltage (kVp) and simultaneously reducing the total number of X-ray views (sparse view) is an effective means to achieve low-dose in computed tomography (CT) scan. However, the associated image quality by the conventional filtered back-projection (FBP) usually degrades due to the excessive quantum noise. Although sparse-view CT reconstruction algorithm via total variation (TV), in the scanning protocol of reducing X-ray tube current, has been demonstrated to be able to result in significant radiation dose reduction while maintain image quality, noticeable patchy artifacts still exist in reconstructed images. In this study, to address the problem of patchy artifacts, we proposed a median prior constrained TV regularization to retain the image quality by introducing an auxiliary vector m in register with the object. Specifically, the approximate action of m is to draw, in each iteration, an object voxel toward its own local median, aiming to improve low-dose image quality with sparse-view projection measurements. Subsequently, an alternating optimization algorithm is adopted to optimize the associative objective function. We refer to the median prior constrained TV regularization as "TV_MP" for simplicity. Experimental results on digital phantoms and clinical phantom demonstrated that the proposed TV_MP with appropriate control parameters can not only ensure a higher signal to noise ratio (SNR) of the reconstructed image, but also its resolution compared with the original TV method. (c) 2015 Elsevier Ltd. All rights reserved.