全数字B超动态滤波器的设计与实现

Design and Realization of a Dynamic Filter in Digital B Mode Ultrasonography

为在全探测深度内获取最佳分辨力的超声回波图像,本研究基于现场可编程门阵列(FPGA)设计了一种动态滤波器,将全数字B超的探测深度平均分为64段,采用64个32阶带通滤波器与之对应,完成人体超声回波信号的动态滤波处理。所设计滤波器应用于128阵元、3.5MHz的全数字B超设备中,并与使用常值滤波器的图像进行了分析比较。通过对仿组织超声体模的检测显示,在图像的探测深度、远场分辨力和噪声滤除等方面都有了较为明显的提高。

This study is aimed to obtain the ultrasonic echo images in all detective depth.A dynamic filter was designed based on field programmable gate array（ FPGA ）.The detective depth of the digital B mode ultrasonography was divided into 64 segments,and sixty four 32-order band-pass filters were adopted to complete the process of the dynamic filtering of human ultrasonic echo signals.Then the design was applied to the digital B mode ultrasonography with 128-elements and the center frequency of 3.5 MHz.With the experiments in tissue mimicking ultrasound phantom,the detective depth,the resolution in far field and the denoising ability were all obviously improved compared with the image created using the fixed filter.