| Summary: | 碩士 === 輔仁大學 === 電機工程學系 === 100 === Ultrasound imaging is a well-established imaging modality and it has been used extensively in clinical diagnosis due to its real time and noninvasive capability. As the frequency of ultrasound imaging increases (>30 MHz), some micro structures of tissue can be observed clearly such as skin, small vessel, eye, embryo of mouse, and the heart of small animals. Currently, some commercial high frequency ultrasound imaging systems are available, however, the prices are expensive and the sizes are huge. In these systems, one of important instrument is the high frequency ultrasound pulser-receiver. However, most high frequency ultrasound pulser-receivers can not provide multi-frequency output signals and the burst cycles can not be adjusted. Consequently, an arbitrary frequency ultrasonic pulse generator-receiver was developed in this study. This system has high voltage signal with low noise, and range of the frequency ranging from 10-50 MHz can be controlled and programmable by using PLL, and the signal was processed by a FPGA board. The high performance and low cost high frequency ultrasound pulser-receiver was developed by the high bandwidth and high speed switch electronic components in this study. Furthermore, this circuit can be applied for high frequency ultrasound imaging and Doppler imaging system. In the experiment on small animals, we measure the detail of zebrafish to observe biological structures, and verify system scanning ability. High frequency ultrasound imaging system are useful diagnosis tool in the measurement of tissue structures in detail ,so we hope in the future that high frequency ultrasound imaging can be applied in the clinical diagnosis.
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