Study On FPGA-based High-frequency Ultrasound Blood Flow Detection Technology And System Implementation

The kinetic parameters of the blood were confirmed that had direct link with thephysiological function of the blood vesseles. Noninvasive visualization of real-timemonitoring of blood flow was used to the early diagnosis, blood disorders cardio-vascular disease determination and evaluation of treatment programs which hadpractical clinical value in the medical field of biological and great demand. Dopplerblood flow detection system with non-invasive, convenient and effective, real-timedisplay and low cost advantages, had been widely used to measure the body’shemodynamic parameters.A new echo signal quadrature demodulation solution was proposed for thehigh-frequency pulsed Doppler ultrasound (greater than20MHz) imaging system,based on the in-depth study of blood flow measurement principle of intravascularblood flow characteristics and pulsed Doppler ultrasound, in this paper.AlteraCycloneIII series EP3C40F484C8Field programmable Gate Array (FPGA) chip wasselected as the control center to achieve full digital signal processing pulsed Dopplerblood flow measurement system. Hardware structure of the system can be dividedinto the excitation of ultrasonic transmitter circuit, differential amplifier and highspeed A/D converter analog front-end module, signal acquisition and digital signalprocessing module, human-computer interaction and data transmission modulespectrum display control module according to the actual function of the system. Thedigital integrated circuit was implemented with miniaturization, low noise,improved stability and reliability of the system. System software was implementedby VHDL language including transducer excitation module, quadraturedemodulation of echo signal and spectrum analysis module, and USB3.0datatransmission module within the FPGA. Pulsed Doppler frequency shift signal wastransferred to the computer for flow velocity spectrum waveforms display by the VCuser interface. Algorithms systems were designed by modular easy to extend the algorithm and system upgrades to meet different needs. The performance of thereal-time system was improved by the high-speed parallel digital signal processingcharacteristics of FPGA.In this paper, an experimental platform was builded which was based onultrasonic Doppler flow velocity physical model, the various parts of the system ofjoint commissioning and testing to verify its correctness.The FPGA based highfrequency pulsed Doppler ultrasound blood flow measurement system can be doneon blood vessels at different depths within the real-time detection was showed in theexperimental results.And a parabolic cross-sectional view of the flow rate also wasgot. While high-frequency ultrasound was confirmed a higher spatial resolution ofthe system on a slow blood flow and good performance on vascular microcirculationdetection.It can be used to assess the function of small animal cardiovascular and hassignificance for the subsequent scientific.