Research On Signal Analysis And Processing Based On Medical Ultrasonic Doppler Technology

Clinical medical research shows that the parameters of blood flow in the blood vesselscan directly reflect the physiological function of blood vessels. It is of great significance for the diagnosis of vascular diseases, treatment and therapeutic effect evaluation. Medical Doppler ultrasound technique is a larger field of medical ultrasound diagnosis. It is based on the principle of the Doppler effect, and medically monitors the blood flow of organs and vessels with a combination technology of physical acoustics and electronic. Medical ultrasound Doppler technique can not only obtain vascular anatomy and morphology, but also can obtain the parameters of flow and velocity through blood flow measurement. The organ function, vascular function or medical effect can be well detected. So, medical Doppler ultrasound technique has good practical value and great prospect in blood flow detection.The Doppler diagnostic equipment emits high frequency sound waves into human body by the transmitting probe.The waves meet different tissues and produce reflection which can be induced by the receiving probe and transmitted to the back-end processing module. Because of the complexity in human blood system, the reflection caused by the ultrasonic propagation in blood and its related organization is also complex, which brings difficulties in the processing and analysis of Doppler ultrasound blood flow signals. This thesis mainly aims at studying and discussing the suppression of vessel wall clutter signal in the field of Doppler ultrasound blood flow signal processing, putting forward a denoising method called "the correlation of wavelet coefficients denoising" for suppressing the wall clutter signal. This method uses the difference between blood flow and wall signal’s correlations in each wavelet scale, so as to achieve the purpose of filtering the clutter. After validation, the method is better than the existing methods of clutter suppression.In order to verify the overall effect of the algorithm, it is necessary to simulate a mixed signal contains the Doppler flow signal and vessel wall clutter signal then analysis and process it. This thesis adopts the optimized Gauss time domain processing method to simulating the Doppler ultrasound blood flow signal. According with the time-frequency characteristics and statistical characteristics of real signals, the result is feasible and effective.Finally, the MATLAB simulation platform of medical ultrasonic Doppler signal analysis and processing is built. Through this platform the Doppler blood flow signal and its processing algorithm can be easily generated, processed, analyzed and evaluated. The platform also provides a variety of functions which are packaged into callable interface, creates a great convenience for the analysis and processing of ultrasonic Doppler signal.