Congratulations to Xi Yang on her successful PhD dissertation defense, and thanks for Chair Professor Mohamad Sawan on her supervision of this thesis project！

On February 28, 2025, a School of Engineering dissertation defense was held in room E2-216, Westlake University. Xi Yang, a PhD candidate of CenBRAIN Neurotech Center of Excellence, successfully defended her doctoral dissertation having the title "Modeling and Analysis of Photoacoustic Imaging Approach for Multi-layer Brain Tissues". Professor Yingke Xu from Zhejiang University was invited to be the chair of the defense committee, Chair Professor Weicheng Cui and Associate Professor Lan Li from Westlake University, Research Professor Junhui Shi from Zhejiang Lab, as well as the Research Professor Fei Gao from University of Science and Technology of China, were the members of the defense committee. Dr. Yun-Hsuan Chen, Research Assistant Professor in Westlake University, was the secretary of this evaluation committee. Several faculty and students from CenBRAIN Neurotech Center of Excellence attended this defense.

After the successful conclusion of the defense, Chair Professor Mohamad Sawan, Dr. Xi Yang's supervisor, and members of the center prepared a celebration party and farewell dinner for her. Xi, holding the gift in her hands, was filled with gratitude. She thanked Professor Sawan for his careful guidance and selfless support along the way. The professor's firm belief and enthusiasm for scientific research had kept her moving forward on her academic path.

Ph.D Graduate

Dr. Xi Yang interests in the non-invasive imaging technique, multi-physical modeling and simulation, signal processing, and image reconstruction. She focuses on photoacoustic imaging of the human brain. During the PhD study at CenBRAIN Neurotech, she has ten publications, including four journal papers and one conference paper as the first author, four papers as first co-author and co-author were published on renowned international journals such as Biosensor and Bioelectronics, Laser & Photonics Reviews and Biosensors, as well as a chapter for Recent Advancements in Smart Remote Patient Monitoring, Wearable Devices, and Diagnostics Systems.

PhD Thesis Abstract

Photoacoustic imaging is a non-radiative biomedical imaging technique that combines the specificity of optical imaging and the penetration depth of acoustic imaging. The challenge in human brain photoacoustic imaging lies in the strong attenuation of incident light by brain tissues, particularly the skull, which significantly reduces the longitudinal transmission depth of the light source in the brain. The key to advancing brain photoacoustic imaging is to find highly penetrative light sources.

Xi Yang’s doctoral thesis constructed a comprehensive brain photoacoustic imaging simulation model based on optical simulation, acoustic simulation, and image reconstruction, focusing on exploring the longitudinal optical penetration depth and lateral diffusion distribution of different light source types in brain tissues, and studying the heterogeneity issues in photoacoustic imaging. Additionally, the simulation model was experimentally validated using a semi-circular photoacoustic imaging system. By gaining a deeper understanding of the optical and acoustic characteristics of different light source types in multi-layered brain tissues, the thesis aims to better optimize the design of photoacoustic imaging systems to improve the quality and accuracy of image reconstruction. This research provides significant theoretical guidance for understanding brain structure and function, diagnosing brain diseases, and conducting neuroscience research.