基于光子计数探测器多能谱CT重建算法及应用研究

发布时间：2018-01-28 21:31

本文关键词： X射线能谱CT 光子计数探测器能谱通道划分 Split-Bregman 彩色CT成像 K边缘值成像　出处：《中北大学》2017年硕士论文　论文类型：学位论文

【摘要】：近年来,随着光子计数探测器技术的快速发展,X射线多能谱CT技术成为CT成像领域的研究热点问题,包括重建算法,能量选择,材料识别等。与传统CT相比,X射线多能谱CT在一次扫描中能得到物体在不同能谱通道下的投影图像,有利于区分物体的材质,提高对比噪声比(CNR)。本文基于光子计数探测技术研究多能谱CT重建算法及应用,主要研究内容如下:(1)多能谱CT重建,多能谱CT可以提供被检测物体在不同能谱维度的衰减图,但由于能谱通道变窄,每个能谱通道内的噪声增加了。为了有效降低通道内的噪声,本文使用基于TV最小化的Split-Bregman算法对X射线多能谱CT进行重建。首先,根据重建模体的先验信息,进行能谱通道的划分。然后,采用Split-Bregman算法对能谱投影数据进行噪声和稀疏角度重建。仿真实验结果表明,基于Split-Bregman算法的能谱CT重建方法能够有效去除能谱通道内的噪声,满足物体材质区分的需求。(2)材质区分与识别,X射线多能谱CT能够提供丰富的有关物质材质的信息。首先通过主成分分析方法对X射线能谱多CT数据进行分析,提取和量化X射线的能谱信息,并融合出彩色CT图像,可直观区分材料的不同物质。其次利用不同物质X射线的吸收特性不同,通过实验研究了不同材料的K边缘特性,进一步评估了X射线多能谱CT材质的鉴别能力。
[Abstract]:In recent years, with the rapid development of photon counting detector technology, X-ray multispectral CT technology has become a hot issue in the field of CT imaging, including reconstruction algorithm, energy selection. Compared with traditional CT, X-ray multispectral CT can get projection images of objects in different energy spectrum channels in a single scan, which is helpful to distinguish the materials of objects. In this paper, the multispectral CT reconstruction algorithm and its application are studied based on photon counting detection technology. The main research contents are as follows: 1) multispectral CT reconstruction. Multi-spectral CT can provide attenuation map of the detected object in different energy spectrum dimensions, but because the energy spectrum channel becomes narrower, the noise in each energy spectrum channel increases, in order to effectively reduce the noise in the channel. In this paper, the Split-Bregman algorithm based on TV minimization is used to reconstruct X-ray multispectral CT. Firstly, the energy spectrum channels are divided according to the priori information of the remodeled volume. The Split-Bregman algorithm is used to reconstruct the noise and sparse angle of the energy spectrum projection data. The simulation results show that. The energy spectrum CT reconstruction method based on Split-Bregman algorithm can effectively remove the noise in the energy spectrum channel and meet the requirements of material differentiation. X-ray multispectral CT can provide abundant information about material material. Firstly, the multi-CT data of X-ray energy spectrum are analyzed by principal component analysis (PCA) to extract and quantify the information of X-ray energy spectrum. The color CT images can be used to distinguish different materials directly. Secondly, the characteristics of K edge of different materials are studied by using different X-ray absorption characteristics of different materials. The discrimination ability of X-ray multispectral CT materials was further evaluated.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP391.41

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