一种甚高频医学超声回波信号高速数据采集系统的设计

Design of high-speed data acquisition system for very high frequency medical ultrasonic echo signals

目的:设计一种甚高频医学超声回波信号高速数据采集系统,以实现高速率和高精度的实时采样。方法:采用内置两路集成模数转换器(analog-to-digital converter,ADC)芯片的LTC2285来实现超声回波信号的模数转换,并将两路采样率为120 MHz的数字信号输入至现场可编程门阵列(field-programmable gate array,FPGA)进行并串转换,得到采样率为240 MHz的高速数字信号进行超声回波数字信号处理,最后将数据通过USB接口传输至计算机终端进行显示。为了保证该系统的可实现性,对该系统进行时序仿真实验、分辨力检测实验和正常人眼前节成像实验。结果:该时序仿真结果验证了由FPGA设计该并转串模块实现的可靠性;该系统的分辨力能达到40μm,满足临床上对眼科超声生物显微镜(ultrasound biomicroscopy,UBM)纵向分辨力的要求;该系统的UBM检查可得到正常人眼前节组织的高分辨力成像图。结论:该系统运用多通道和FPGA技术,提高了采集速度和可靠性,为最终的UBM实时成像奠定了前期实验基础。

Objective To develop a high-speed data acquisition system for very high frequency medical ultrasonic echo signals.Methods The chip LTC2285 with two integrated ADC channels was adopted to realize analog-to-digital conversion of ultrasonic echo signals.The sampling rate was 120 MHz.The converted digital signals were then input to the FPGA to realize parallel to serial conversion, and high-speed digital signals with a sampling rate of 240 MHz were obtained.Finally,the data were transferred through USB interface to the computer terminal to display.Results A timing simulation experiment,a resolution detection experiment, and an in vivo experiment of normal human eyes were carried out in this system.A preferable simulation result and real-time image were obtained.Conclusion The multi-channel and FPGA technology are used in the design of the system.Lastly, this technology simplifies the overall design of the system and improves the speed and reliability of the high speed data acquisition system.