Color Doppler Ultrasound Signal Processing Based On FPGA

With the continuous progress of medical ultrasound imaging technology, thedemands on the quality and speed of the imaging are increasing day by day. ColorDoppler ultrasound signal processing is characterized by a large amount of data, highaccuracy, as well as real-time requirements. With the development of semiconductortechnology, semiconductor manufacturers have also launched a high-performance signalprocessing platform to meet the ultrasound imaging equipment. Especially theemergence of parallel processing technology in the field programmable gate array(FPGA) greatly enhanced color Doppler ultrasound signal processing capabilities.Aimed at above problems, this thesis focuses on the field programmable gate array(FPGA) application in color Doppler signal processing and discusses the signalprocessing on the basis of in-depth analysis of the technical principles of today’s colorDoppler technology:1. FPGA system designColor Doppler ultrasound signal processing system is a high-speed real-time signalprocessing system, which is characterized by a large amount of front-end data andprocessing real-time requirements, the design of the entire hardware system is the basisof imaging, and also determines the quality of the image.2. Color Doppler RF signal demodulationSince the RF signal is in the megahertz frequency bands above, we use thequadrature demodulation to process the RF signal. In this case, the amount of data to beprocessed is very large, so, we require the demodulation algorithm with high real-time.3. Wall filter designObtained the demodulated data, in order to eliminate a substantial echo signalsreflected from a stable or slow moving tissue, which have a small Doppler frequencyshift, we will use the wall filter to suppress the low-frequency signal. The selection,parameter settings, and the frequency response of wall filter will affect the image quality,so, there is a great challenge of the wall filter design.4. Flow information estimation First, use the demodulated quadrature-phase data to calculate the power spectrum,and then estimate the information of the flow taking advantage of autocorrelationtechniques. Then, some critical threshold settings and adjustments will have a hugeimpact on the back of imaging quality. So, continue to select the appropriate thresholdfor debugging will be the key to this part of the work.5. Display and verification. Taking advantage of comparative analysis to verify thecorrectness of hardware logic processing and lay the foundation for the followingengineering practice.