Development of a Chirp Coded Excitation Ultrasound System with Contrast Agents for Small Animal Imaging

Abstract

In recent years high frequency ultrasound is widely researched because the high-frequency ultrasound imaging system has higher resolution which observes the superficial tissue such as blood vascular eyes skin tissue of small animals etc The high-frequency ultrasound system usually uses short pulse as trigger signal it has better resolution but the attenuation effect of tissue in the human attenuates the ultrasound energy limiting the signal-to-noise ratio (SNR) and the penetration depth Therefore this thesis develops a chirp coded excitation ultrasound system The Gaussian chirp coded excitation is used as a trigger signal for raising average power to achieve better SNR and penetration depth After that pulse compression filter is applied to the echo signal for enhancing SNR and axial resolution According to experiment results there are a 15dB SNR improvement and a 1-2mm penetration depth improvement by chirp-coded excitation pulse compression and the handmade expander for noise reduction In the experiment of microbubble (MB) imaging & destruction finding the appropriate concentration and the parameters of destruction signal achieves desired MBs size distribution for different types of MBs The resonant frequency of microbubbles is much closer the signal frequency to increase the scattering area of microbubbles The zebrafish plays an important role in regenerative medical The organs of the zebrafish have self-healing ability and the heart of the zebrafish recovers after damage Hence the MBs are injected in the zebrafish to enhance image contrast to clearly observe the ventricle and the atrium of the heart of the zebrafish and get more information According to the enhancement of SNR and penetration depth in high-frequency ultrasound system more useful information is provided for the biological research and medical diagnosis

Date of Award	2014 Aug 22
Original language	English
Supervisor	Tainsong Chen (Supervisor)