诊断超声宽带声束形成技术研究与实现
发布时间：2018-12-11 21:35
【摘要】：诊断超声成像具有安全无创、实时、廉价、便携等优点,被广泛用于人体软组织病变与流态组织特性的诊断,目前已成为必不可缺的临床医学诊断方法之一。作为诊断超声成像系统的前端数据获取与信号处理单元,声束形成器性能的优劣直接决定了成像的质量。传统的基于延时累加的声束形成技术采用动态聚焦技术、动态孔径技术以及动态变迹技术改善声束的指向性,但仍存在着声束旁瓣较高、主瓣宽度不够窄等问题,导致最终成像的空间分辨率和对比度分辨率不足。本文针对动态聚焦中数字时延精度不足导致的旁瓣幅值大,以及传统窗函数变迹方法导致的主瓣展宽问题,着重进行了如下几个方面的研究:1、对超声成像系统及其性能评价指标进行了分析,研究了声束形成技术的相关理论,给出了声束形成技术的三种不同实现结构的对比分析,重点分析了声束形成技术中的时延精度与成像性能指标之间的关系,并对宽带声束形成技术进行了讨论。2、研究了基于可变分数时延Farrow滤波器的动态聚焦方法。对用于拟合可变分数时延Farrow滤波器的三种原型滤波器组的设计方法进行了仿真分析,并给出了三个有关时延幅度误差和相位误差的对比分析,仿真表明,可变分数时延Farrow滤波器可提高延时精度,有效消除图像尾影。3、针对传统延时累加声束形成器中变迹导致的主瓣宽度展宽的问题,研究了宽带FIR声束形成技术的原理及实现结构,并基于通用囊性分辨率准则,详细论述了利用约束最小二乘(CLS)最佳变迹法设计宽带FIR声束形成器变迹系数的方法。仿真表明,宽带FIR声束形成器能够在降低旁瓣的同时获得更窄的声束主瓣。4、对基于FPGA的宽带声束形成器的优化实现方法进行了研究。首先,针对分数时延Farrow滤波器的结构特性,对声束形成器的实现结构进行了优化,提出了双分数时延值输入Farrow滤波器;其次,在节约乘法器资源方面,对Farrow滤波器的实现提出了优化方法;最后验证、分析了宽带声束形成的成像效果及其硬件资源消耗。
[Abstract]:Diagnostic ultrasound imaging has the advantages of safe, non-invasive, real-time, cheap and portable. It has been widely used in the diagnosis of soft tissue lesions and fluid tissue characteristics, and has become one of the indispensable clinical diagnostic methods. As the front-end data acquisition and signal processing unit of diagnostic ultrasonic imaging system, the quality of imaging is directly determined by the performance of acoustic beam forming device. The traditional acoustic beam forming technology based on delay accumulation uses dynamic focusing technology, dynamic aperture technology and dynamic apodization technology to improve the directivity of sound beam, but there are still some problems such as high sidelobe and narrow width of main lobe. As a result, the spatial resolution and contrast resolution of the final imaging are insufficient. In this paper, we focus on the following aspects: 1. Aiming at the large amplitude of sidelobe caused by the lack of digital delay precision in dynamic focusing and the main lobe broadening caused by traditional window function change method, this paper focuses on the following aspects: 1. This paper analyzes the ultrasonic imaging system and its performance evaluation index, studies the relevant theory of acoustic beam formation technology, and gives a comparative analysis of three different structures of acoustic beam formation technology. The relationship between delay accuracy and imaging performance in acoustic beam forming technology is analyzed, and the wideband acoustic beam forming technique is discussed. 2. Dynamic focusing method based on variable fractional delay Farrow filter is studied. The design methods of three kinds of prototype filter banks used to fit Farrow filters with variable fractional delay are simulated and analyzed, and three comparative analysis of delay amplitude error and phase error are given. The simulation results show that, The variable fractional delay Farrow filter can improve the delay accuracy and effectively eliminate the image tail. 3. Aiming at the problem of widening the width of the main lobe caused by the change point in the traditional time-delay accumulative acoustic beam formator, The principle and structure of broadband FIR acoustic beam formation technology are studied. Based on the general cystic resolution criterion, the method of designing the acoustical coefficient of broadband FIR acoustic beam forming device using constrained least square (CLS) optimal apodization method is discussed in detail. The simulation results show that the wideband FIR acoustic beam formator can obtain narrower main lobe while reducing the sidelobe. 4. The optimization method of the broadband acoustic beam generator based on FPGA is studied. Firstly, according to the structural characteristics of fractional delay Farrow filter, the structure of acoustic beam formator is optimized, and a double fractional delay input Farrow filter is proposed. Secondly, in the aspect of saving multiplier resources, the optimization method of Farrow filter is proposed. Finally, the imaging effect of broadband acoustic beam formation and the consumption of hardware resources are analyzed.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TP391.41;TB559
本文编号：2373259
[Abstract]:Diagnostic ultrasound imaging has the advantages of safe, non-invasive, real-time, cheap and portable. It has been widely used in the diagnosis of soft tissue lesions and fluid tissue characteristics, and has become one of the indispensable clinical diagnostic methods. As the front-end data acquisition and signal processing unit of diagnostic ultrasonic imaging system, the quality of imaging is directly determined by the performance of acoustic beam forming device. The traditional acoustic beam forming technology based on delay accumulation uses dynamic focusing technology, dynamic aperture technology and dynamic apodization technology to improve the directivity of sound beam, but there are still some problems such as high sidelobe and narrow width of main lobe. As a result, the spatial resolution and contrast resolution of the final imaging are insufficient. In this paper, we focus on the following aspects: 1. Aiming at the large amplitude of sidelobe caused by the lack of digital delay precision in dynamic focusing and the main lobe broadening caused by traditional window function change method, this paper focuses on the following aspects: 1. This paper analyzes the ultrasonic imaging system and its performance evaluation index, studies the relevant theory of acoustic beam formation technology, and gives a comparative analysis of three different structures of acoustic beam formation technology. The relationship between delay accuracy and imaging performance in acoustic beam forming technology is analyzed, and the wideband acoustic beam forming technique is discussed. 2. Dynamic focusing method based on variable fractional delay Farrow filter is studied. The design methods of three kinds of prototype filter banks used to fit Farrow filters with variable fractional delay are simulated and analyzed, and three comparative analysis of delay amplitude error and phase error are given. The simulation results show that, The variable fractional delay Farrow filter can improve the delay accuracy and effectively eliminate the image tail. 3. Aiming at the problem of widening the width of the main lobe caused by the change point in the traditional time-delay accumulative acoustic beam formator, The principle and structure of broadband FIR acoustic beam formation technology are studied. Based on the general cystic resolution criterion, the method of designing the acoustical coefficient of broadband FIR acoustic beam forming device using constrained least square (CLS) optimal apodization method is discussed in detail. The simulation results show that the wideband FIR acoustic beam formator can obtain narrower main lobe while reducing the sidelobe. 4. The optimization method of the broadband acoustic beam generator based on FPGA is studied. Firstly, according to the structural characteristics of fractional delay Farrow filter, the structure of acoustic beam formator is optimized, and a double fractional delay input Farrow filter is proposed. Secondly, in the aspect of saving multiplier resources, the optimization method of Farrow filter is proposed. Finally, the imaging effect of broadband acoustic beam formation and the consumption of hardware resources are analyzed.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TP391.41;TB559
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