X射线真彩色CT图像重建研究

项目名称： X射线真彩色CT图像重建研究

项目编号： No.61302136

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 无线电电子学、电信技术

项目作者： 许琼

作者单位： 西安交通大学

项目金额： 28万元

中文摘要： 使用光子计数探测器的X射线CT系统能同时采集多个能量通道的投影数据，进行彩色成像，称为光谱CT（Spectral CT）、多能谱CT（Multi-energy CT）、真彩色或彩色CT（True-color/color CT）。本项目围绕真彩色CT的图像重建问题展开研究。针对多能谱数据每个能谱通道上光子数少、噪声大的问题，提出使用基于字典学习等稀疏性约束的统计迭代重建与多能谱数据特性相结合的重建方法；针对大尺寸的光子计数探测器制造工艺难度大、价格高的问题，提出使用内部扫描方式，并提出在多光谱内重建中使用全局灰度重建结果作为先验约束的多光谱内重建方法；针对真彩色图像的彩色生成问题，提出将统计分析方法与成像物理学过程相结合的非线性彩色映射和定量彩色生成方法。通过本项目的研究形成一套完整的高性能真彩色CT图像重建方案，提高真彩色CT的成像质量、降低成像成本，为其实际应用打下基础。

中文关键词： 迭代重建；低剂量CT；内重建；双能CT；多能CT

英文摘要： True-color CT (spectral CT /multi-energy CT) is an important development due to the merits of k-edge imaging and material decomposition in biomedical imaging. The most critical limitations with current true-color x-ray detectors are threefold: cost, size and radiation dose. Current true-color detectors are both small and expensive. Radiation dose is a concern for any x-ray-based system, and energy bins for each true-color channel require higher total exposure relative to a single-channel energy-integrating detector. Furthermore, the maximum detectable x-ray flux is limited by the detector readout speed (due to pulse pileup). In this proposal, we aim to develop an image reconstruction method to improve the image quality while reducing the cost and radiation for true-color CT. Our research is divided into two parts: one is the image reconstruction on each energy bin and the other is the color mapping. Our solutions are three folds. Firstly, the reconstruction on each energy bin is a low-count issue. However, the data on one energy channel is related to another one. Recently, a dictionary learning based sparsity constraint has been proved to perform well for low-count data, with preserving details and suppressing noise as much as possible. We propose to incorporate the correlations among multi-energy bins and the d

英文关键词： Iterative reconstruction；low-dose CT；interior tomography；dual-energy CT；multi-energy CT