高频超声诊断仪中自适应动态滤波器的研究

发布时间：2018-07-21 10:32

【摘要】：在超声诊断技术不断发展的形势下,各类专科超声诊断设备也得到了很大的发展,其中眼科超声诊断仪是发展最快速的专科超声诊断设备之一。随着现代科学技术的发展,医学超声仪器在探头、信号检测与处理、计算机应用等各个方面的技术不断更新和提高。为了满足临床诊断的需要,进一步全面提高系统的性能,包括探查深度、空间分辨率、成像速率,灵敏度等指标一直还是工程开发人员致力研究的目标。本文就其自适应动态滤波器的设计做了详细的研究。首先分析了自动匹配动态滤波算法的理论意义,接着对算法的原理和硬件结构做了相应的描述。其次详细介绍了系统中FIR滤波器模块和FFT处理器两个关键模块的基本原理及各自的几种硬件结构,以及FFT处理器的硬件优化的措施和方法。然后结合目前广泛应用于超声系统的FPGA技术给出了各个模块的实现方案。在本文中,详细阐述了基于全并行分布式算法的级联型FIR滤波器模块和基2-DIF定点高速并行迭代式FFT处理器模块的FPGA实现方案。通过仿真验证,证明该算法的可行性。最后以前面选出的适合的子模块为基础,实现了能够应用于现有的眼科高频B超诊断系统中的自适应动态滤波器,对仿组织超声体模块进行图像采集,与传统的滤波器相比获得了良好的效果,增加了探测深度,提高图像灵敏度。本文设计的自动匹配的动态滤波器能够实时的分析回波信号的频谱特性,适时调整动态滤波器的中心频率,达到了预期的设计要求。另外,FFT处理器模块也可以单独作为一个工具,为以后研究多普勒血流测量系统打下基础。
[Abstract]:With the continuous development of ultrasonic diagnostic technology, various kinds of specialized ultrasonic diagnostic equipment have also been greatly developed, among which the ophthalmic ultrasound diagnostic apparatus is one of the fastest developing specialized ultrasonic diagnostic equipment. With the development of modern science and technology, the technology of medical ultrasonic instruments in probe, signal detection and processing, computer application and so on is constantly updated and improved. In order to meet the needs of clinical diagnosis and further improve the performance of the system, including exploration depth, spatial resolution, imaging rate, sensitivity and other indicators has always been the goal of engineering developers. In this paper, the design of adaptive dynamic filter is studied in detail. This paper first analyzes the theoretical significance of the automatic matching dynamic filtering algorithm, and then describes the principle and hardware structure of the algorithm. Secondly, the basic principle of the two key modules of Fir filter module and FFT processor and their respective hardware structures are introduced in detail, as well as the measures and methods of hardware optimization of FFT processor. Then combined with FPGA technology which is widely used in ultrasonic system at present, the implementation scheme of each module is given. In this paper, the FPGA implementation scheme of cascaded Fir filter module and radix-2-DIF fixed-point high-speed parallel iterative FFT processor module based on full parallel distributed algorithm is described in detail. The feasibility of the algorithm is proved by simulation. Finally, on the basis of the suitable sub-modules, the adaptive dynamic filter which can be used in the existing ophthalmic high-frequency B ultrasonic diagnosis system is realized, and the image acquisition of the imitating tissue ultrasonic volume module is carried out. Compared with the traditional filter, it has a good effect, increases the detection depth and improves the image sensitivity. The automatic matching dynamic filter designed in this paper can analyze the spectrum characteristics of echo signal in real time and adjust the center frequency of the dynamic filter in time to meet the expected design requirements. In addition, the FFT processor module can also be used as a tool to lay the foundation for the future study of Doppler blood flow measurement system.
【学位授予单位】：北京协和医学院
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R318.6

【共引文献】