Scatter correction for full-fan volumetric CT using a stationary beam blocker in a single full scan
Scatter correction for full-fan volumetric CT using a stationary beam blocker in a single full scan
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DOI：
10.1118/1.3651619
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发表时间：
2011-11-01
期刊：
影响因子：
3.8
通讯作者：
Zhu, Lei
中科院分区：
文献类型：
--
作者：
Niu, Tianye;Zhu, Lei
目的：重建图像中的阴影和条纹伪影阻碍了体积CT（VCT）的应用。这些伪影主要是由于强X射线散射信号伴随着一个投影内的大照明区域，这导致CT数不准确，图像对比度损失和空间不均匀性。虽然在文献中已经提出了不同的散射校正算法，但标准的解决方案仍然不清楚。基于测量的方法使用光束阻断器来获取散射样本。这些技术具有无与伦比的优势，在其他现有的算法，因为它们是简单和有效的，并实现高散射估计精度，而无需成像对象的先验知识。然而，在散射测量中主要信号损失是不可避免的，并且在数据采集期间通常采用多次扫描或移动光束阻挡器来补偿丢失的主要数据。在本文中，我们提出了一种新的测量为基础的散射校正算法，无需初级补偿全风扇VCT。通过一次单扫描和一个固定的X射线束阻挡器获得精确的重建，这两个看似不相容的功能可以在不增加扫描时间或患者剂量的情况下实现简单有效的散射校正。方法：基于CT重建理论，我们将分块数据分布在全扫描中原始信号被认为是近似冗余的投影区域上，使得即使有一次损失也不会降低CT图像质量。散射，然后准确地估计插值和散射校正的CT图像得到使用FDK为基础的重建algorithm.Results：所提出的方法进行评估，使用两个幻影研究的桌面CBCT系统。在Catphan（c）600体模上，我们的方法将所选感兴趣区域的重建误差从207 Hounsfield单位（HU）降低到9 HU，并将高对比度区域的图像对比度提高了2.0倍。在一个拟人的头部模型，重建误差从97 HU减少到6 HU的软组织区域和图像的空间不均匀性从27%减少到5%.Conclusions：我们的方法继承了测量为基础的方法的主要优点，同时避免了他们的缺点。它有可能成为一个实用的散射校正解决方案，广泛适用于不同的VCT系统。(C)2011年美国医学物理学家协会。[DOI 10.1118/1.3651619]
Purpose: Applications of volumetric CT (VCT) are hampered by shading and streaking artifacts in the reconstructed images. These artifacts are mainly due to strong x-ray scatter signals accompanied with the large illumination area within one projection, which lead to CT number inaccuracy, image contrast loss and spatial nonuniformity. Although different scatter correction algorithms have been proposed in literature, a standard solution still remains unclear. Measurement-based methods use a beam blocker to acquire scatter samples. These techniques have unrivaled advantages over other existing algorithms in that they are simple and efficient, and achieve high scatter estimation accuracy without prior knowledge of the imaged object. Nevertheless, primary signal loss is inevitable in the scatter measurement, and multiple scans or moving the beam blocker during data acquisition are typically employed to compensate for the missing primary data. In this paper, we propose a new measurement-based scatter correction algorithm without primary compensation for full-fan VCT. An accurate reconstruction is obtained with one single-scan and a stationary x-ray beam blocker, two seemingly incompatible features which enable simple and efficient scatter correction without increase of scan time or patient dose.Methods: Based on the CT reconstruction theory, we distribute the blocked data over the projection area where primary signals are considered approximately redundant in a full scan, such that the CT image quality is not degraded even with primary loss. Scatter is then accurately estimated by interpolation and scatter-corrected CT images are obtained using an FDK-based reconstruction algorithm.Results: The proposed method is evaluated using two phantom studies on a tabletop CBCT system. On the Catphan (c) 600 phantom, our approach reduces the reconstruction error from 207 Hounsfield unit (HU) to 9 HU in the selected region of interest, and improves the image contrast by a factor of 2.0 in the high-contrast regions. On an anthropomorphic head phantom, the reconstruction error is reduced from 97 HU to 6 HU in the soft tissue region and image spatial nonuniformity decreases from 27% to 5% after correction.Conclusions: Our method inherits the main advantages of measurement-based methods while avoiding their shortcomings. It has the potential to become a practical scatter correction solution widely implementable on different VCT systems. (C) 2011 American Association of Physicists in Medicine. [DOI: 10.1118/1.3651619]