Research And Implementation Of A System Of B-mode Blood Flow Imaging Via High Frequency Ultrasound

Medical ultrasound imaging systems are widely used with the advantages of non-invasive, safe, effective and real-time imaging in clinical diagnosis. The most widely used are Doppler flow imaging and B-flow Imaging. But in high frequency conditions, Doppler and coded excitation technique are limited, so we presented a new, gray-scale blood flow imaging via high frequency ultrasound.We study the new blood flow imaging via the high frequency ultrasound based on the research of backscatter signal of blood flow from high frequency ultrasound, which is different from Doppler and coded excitation technology.Firstly we established a scattering model of red blood cells for ultrasound which is according with Rayleigh-scattering. In order to analyze feasibility of blood flow imaging directly in the superficial part via the high frequency ultrasound, we studied the characteristics of the scattering of red blood cells for high frequency ultrasound and the high frequency ultrasound attenuation in the superficial part. Secondly, we introduce the design of the system and the method of the subtraction of pulse echo from algorithms and the implementation in FPGA. Then we use the system to detective simulated the human blood and human blood vessels, and obtained the blood flow imaging similar to the actual results, which could distinguish the blood flow within the 0.3mm blood vessel.We present a method of weight of scattering signal in FPGA and two methods of based on the corrosion and dilation method and based of the gray threshold method to filter noise from tissue. Then we do the pseudo-color coding for blood flow and add it to the tissue imaging. All of the above we did by matlab firstly, and then achieved them in the software of the system with C++under the conditions of the image processing time.By using single pulse emitting to detect the superficial blood vessel, abundant of blood flow signals can be obtained even. The satisfied blood flow backscattering signals can be obtained and achieved the same high resolution structural imaging, and provided a reliable reference for the diagnosis of the superficial organs.