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首页> 外文会议>Physics of Medical Imaging pt.3; Progress in Biomedical Optics and Imaging; vol.7 no.28 >Noise Reduction for Low-Dose Helical CT by Fully 3D Penalized Weighted Least-Squares Sinogram Smoothing
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Noise Reduction for Low-Dose Helical CT by Fully 3D Penalized Weighted Least-Squares Sinogram Smoothing

机译：通过全3D加权加权最小二乘法Singram平滑减少低剂量螺旋CT的噪声

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摘要

Helical computed tomography (HCT) has several advantages over conventional step-and-shoot CT for imaging a relatively large object, especially for dynamic studies. However, HCT may increase X-ray exposure significantly to the patient. This work aims to reduce the radiation by lowering the X-ray tube current (mA) and filtering the low-mA (or dose) sinogram noise. Based on the noise properties of HCT sinogram, a three-dimensional (3D) penalized weighted least-squares (PWLS) objective function was constructed and an optimal sinogram was estimated by minimizing the objective function. To consider the difference of signal correlation among different direction of the HCT sinogram, an anisotropic Markov random filed (MRF) Gibbs function was designed as the penalty. The minimization of the objection function was performed by iterative Gauss-Seidel updating strategy. The effectiveness of the 3D-PWLS sinogram smoothing for low-dose HCT was demonstrated by a 3D Shepp-Logan head phantom study. Comparison studies with our previously developed KL domain PWLS sinogram smoothing algorithm indicate that the KL+2D-PWLS algorithm shows better performance on in-plane noise-resolution trade-off while the 3D-PLWS shows better performance on z-axis noise-resolution trade-off. Receiver operating characteristic (ROC) studies by using channelized Hotelling observer (CHO) shows that 3D-PWLS and KL+2DPWLS algorithms have similar performance on detectability in low-contrast environment.
机译：螺旋计算机断层扫描（HCT）在成像较大物体（尤其是动态研究）时，具有优于常规步进CT的多个优点。但是，HCT可能会显着增加患者的X射线暴露量。这项工作旨在通过降低X射线管电流（mA）并过滤低mA（或剂量）正弦图噪声来减少辐射。基于HCT正弦图的噪声特性，构建了三维（3D）惩罚加权最小二乘（PWLS）目标函数，并通过最小化目标函数来估计最佳正弦图。为了考虑HCT曲线图不同方向之间信号相关性的差异，设计了各向异性马尔可夫随机场（MRF）Gibbs函数作为惩罚。反对函数的最小化是通过迭代的高斯-赛德尔更新策略进行的。通过3D Shepp-Logan头部模型研究证明了3D-PWLS正弦图平滑处理对于低剂量HCT的有效性。与我们先前开发的KL域PWLS正弦图平滑算法的比较研究表明，KL + 2D-PWLS算法在平面内噪声分辨率的权衡中显示出更好的性能，而3D-PLWS在z轴噪声分辨率的交易中显示出更好的性能。 -关。使用信道化的Hotelling观测器（CHO）进行的接收器工作特性（ROC）研究表明，在低对比度环境下，3D-PWLS和KL + 2DPWLS算法在可检测性方面具有相似的性能。

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