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Ning Zhang

Wadham College

Overseas Studentship

Current Research

Electromagnetic Acoustic (EMA) imaging

Electro-Magnetic Acoustic (EMA) imaging is an emerging medical imaging modality. In EMA both the change in dielectric properties and stiffness are exploit to form EMA images therefore provide enhanced contrast compared to conventional ultrasound. The translation of EMA technique to clinic requires shorter scan time to be implemented which in turn requires the noise performance of the EMA scanner to be improved. I have characterized the SNR of the prototype EMA scanner and therefore established an objective metric for the noise reduction work. The PLL demodulator is the core component of the EMA scanner and noise analysis for the PLL has been performed. Analytical expressions and Simulink models have been derived or constructed for the PLL and two noise sources originated from the voltage controlled oscillator (VCO) and good agreement was obtained therefore establishing a viable analysis tool for future development.

In the future other important noise sources will be identified and characterized, which will provide guidance for the noise reduction work of the PLL.