激光宽场多普勒血液流速系统关键技术研究

发布时间：2018-08-29 17:12

【摘要】：血液与人体健康不可分割,通过研究血液微循环系统可以得到身体组织病变情况,例如烧伤、眼底疾病等。传统血液流速的检测方法主要是超声波,但是超声波横向分辨率不足,只能够测量动脉和较粗静脉血流,无法检测血液微循环系统。而采用激光多普勒测血流,可以满足血液微循环系统检测横向分辨率的要求,又具有无创性、操作简单等优点,在临床医学上有广泛的应用价值,所以在国内外医疗器械方面备受关注。通过查阅相关文献研究了多种激光多普勒血液流速系统后,本设计摒弃单点和扫描式测血流的方法,而选择目前具有代表性的激光宽场多普勒成像测血流技术做为主要研究对象。主要研究内容如下:1.深入学习光外差干涉理论和血液灌注成像理论,结合激光多普勒血液流速系统特点,对光源、图像传感器等关键器件进行选型。综合分析现有实验系统结构,设计了一种新式检测光路系统。2.完成高帧频图像采集系统硬件电路设计,包括:图像传感器控制电路、现场可编程门阵列(FPGA)交互电路、同步动态存储器(SDRAM)控制电路、单片机STC51接口电路和CY7C68013A外围电路。在PCB设计阶段进行串扰仿真和反射仿真,确定器件走线拓扑结构、端接方式、板层结构等规则约束,并绘制PCB板。3.激光宽场多普勒血液流速系统软件设计,包括:FPGA时钟管理程序设计、图像传感器控制程序设计、SDRAM读写程序设计、CY7C68013A读写程序设计、CY7C68013A固件程序和USB 2.0上位机控制程序设计等。程序模块之间采用仿顺序操作和并行操作相结合的方式进行交互,并利用Modelsim-Altera对每个逻辑模块进行仿真。最后,利用Labview中的VISA控件完成了上位机界面制作,并与高帧频图像采集系统建立通信。4.利用自主设计的高帧频图像采集设备搭建了实验系统,对活体皮肤组织进行成像,系统采样帧频为8kfps,得到组织血液微循环系统灌注成像图最大分辨率为64x64,并能够清晰看到血流图变化。通过进一步白板实验研究,消除了实验系统噪声对血流成像产生的影响,并对血液灌注成像影响因素进行了分析。
[Abstract]:Blood is inseparable from human health. By studying the blood microcirculation system, we can obtain pathological changes of the body, such as burns, fundus diseases and so on. Ultrasonic is the main method to detect blood velocity, but ultrasonic is not enough to measure arterial and coarse venous blood flow, and can not detect blood microcirculation system. Laser Doppler measurement of blood flow can meet the requirements of blood microcirculation system for lateral resolution, and has the advantages of non-invasive, simple operation, etc., and has wide application value in clinical medicine. So in the domestic and foreign medical devices concerned. After the study of various laser Doppler blood flow velocity systems, the method of single point and scanning blood flow measurement was abandoned in this design. The main research object is laser wide-field Doppler imaging. The main research contents are as follows: 1. The light heterodyne interference theory and blood perfusion imaging theory are studied in depth. Combined with the characteristics of laser Doppler blood velocity system, the light source, image sensor and other key devices are selected. Based on the analysis of the existing experimental system structure, a new detection optical path system. 2. 2 was designed. The hardware circuit design of high frame rate image acquisition system includes: image sensor control circuit, field programmable gate array (FPGA) interactive circuit, synchronous dynamic memory (SDRAM) control circuit, MCU STC51 interface circuit and CY7C68013A peripheral circuit. Crosstalk simulation and reflection simulation are carried out in the design phase of PCB to determine the circuit topology, termination mode and layer structure of the device, and draw the PCB board. 3. The software design of laser wide field Doppler blood flow velocity system includes the design of clock management program on USB, the control program of image sensor and the reading and writing program of SDRAM. The firmware program of CY7C68013A and the control program of USB 2.0 are designed. The program modules interact with each other by the combination of sequence operation and parallel operation, and each logic module is simulated by Modelsim-Altera. Finally, the upper computer interface is made by using the VISA control in Labview, and the communication with the high frame rate image acquisition system is established. 4. An experimental system was set up using the self-designed high frame rate image acquisition equipment to image the skin tissue in vivo. The maximum resolution of perfusion imaging of tissue blood microcirculation system is 64 x 64, and the change of blood flow graph can be clearly seen. The influence of experimental system noise on blood flow imaging is eliminated by further whiteboard experiment and the influencing factors of blood perfusion imaging 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】：2017
【分类号】：R318;TP391.41

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