Half-scan fan-beam computed tomography with improved noise and resolution properties.
Half-scan fan-beam computed tomography with improved noise and resolution properties.
复制标题
半扫描扇形束计算机断层扫描具有改进的噪声和分辨率特性。
DOI：
10.1118/1.1607507
复制
发表时间：
2003
期刊：
影响因子：
3.8
通讯作者：
Pan,Xiaochuan
中科院分区：
文献类型：
--
作者：
Yu,Lifeng;Pan,Xiaochuan
在扇束计算机断层扫描(CT)中，半扫描策略可用于减少扫描时间和辐射剂量。在螺旋CT中，数据加权/内插函数通常是基于半扫描配置来设计的。半扫描扇束滤波反投影(FFBP)算法通常用于从半扫描数据重建图像。然而，对于短焦距和/或大扇角的配置，它可能容易受到样本混叠和数据噪声的影响，导致重建图像中的分辨率和噪声特性不均匀。通常需要统一的分辨率和噪声特性，因为它们可以导致重建图像在估计和/或检测/分类任务中的效用增加。在这项工作中，我们提出了一种在半扫描CT中重建具有均匀噪声和分辨率的图像的算法。为了评估图像噪声特性，我们推导了使用半扫描算法获得的图像方差的解析表达式。我们还进行了数值研究，以定量评估算法的分辨率和噪声特性。这些研究的结果证实，与半扫描FFBP算法相比，该算法生成的图像具有更均匀的空间分辨率和更低、更均匀的噪声水平。在噪声研究中获得的经验结果也验证了所导出的图像方差表达式的有效性。所提出的算法对于利用短焦距和大测量范围的配置获取的数据进行图像重建特别有用，这在紧凑型微型CT和放射治疗CT应用中可能会遇到。图像噪声特性的分析结果可用于利用模型观测器进行检测/分类任务的图像质量评估。
Half‐scan strategy can be used for reducing scanning time and radiation dose delivered to the patient in fan‐beam computed tomography (CT). In helical CT, the data weighting/interpolation functions are often devised based upon half‐scan configurations. The half‐scan fan‐beam filtered backprojection (FFBP) algorithm is generally used for image reconstruction from half‐scan data. It can, however, be susceptible to sample aliasing and data noise for configurations with short focal lengths and/or large fan‐angles, leading to nonuniform resolution and noise properties in reconstructed images. Uniform resolution and noise properties are generally desired because they may lead to an increased utility of reconstructed images in estimation and/or detection/classification tasks. In this work, we propose an algorithm for reconstruction of images with uniform noise and resolution properties in half‐scan CT. In an attempt to evaluate the image‐noise properties, we derive analytic expressions for image variances obtained by use of the half‐scan algorithms. We also perform numerical studies to assess quantitatively the resolution and noise properties of the algorithms. The results in these studies confirm that the proposed algorithm yields images with more uniform spatial resolution and with lower and more uniform noise levels than does the half‐scan FFBP algorithm. Empirical results obtained in noise studies also verify the validity of the derived expressions for image variances. The proposed algorithm would be particularly useful for image reconstruction from data acquired by use of configurations with short focal lengths and large field of measurement, which may be encountered in compact micro‐CT and radiation therapeutic CT applications. The analytic results of the image‐noise properties can be used for image‐quality assessment in detection/classification tasks by use of model‐observers.