| Summary: | 碩士 === 國立中正大學 === 機械系 === 91 === In general clinical diagnosis, one cardinal tool for blood flow measurement that usually use is ultrasound. It is because the diagnosis of using ultrasound has many advantages, including non-invasive, no radiation, higher safety, real-time imaging and low cost. It has become a necessary tool in the clinic to help a physician examine a patient in recent years. Particular in the field of blood velocity measurement, real time ultrasound scanner can display the blood vessel and the physician can observe the streaming flow condition and the organic disturbance. It is not only faster but also accuracy. It has the advantages such that other instruments cannot achieve.
Current clinical ultrasound instrument can only provide video output signal and this might limit the data acquisition and digital signal processing from the current clinical systems. To develop new technique in ultrasonic measurement, the experiment setup in this thesis is to use ultrasound pulser instrument for generating pulse waves to excite the transducer. The received data are then obtained through the tube of UHDC flow phantom and saved by communication interface of computer (GPIB). Using digital signal processing methods processed this data.
One objective of this thesis is to measure the flow velocity using the acquired data. Three different approaches are presented. The flow velocity is computed by using Spectral analysis (FFT), autocorrelation method, and cross-correlation method. The comparisons of these three methods are performed.
Finally, the wavelet decomposition method is used to get the information of blood vessel in RF signal. Combining the autocorrelation method with the wavelet approach, we can analyze the blood volume velocity within the measurement type. The technique might provide an alterative way to estimate the blood volume velocity more quickly and more economic.
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