As a part of my Ph.D. works on NP-enhanced FUS therapy, I studied the physics of the interaction between ultrasonic waves and NPs, so that I could develop an analytical model for FUS’s thermal effect in the presence of nanoparticles (NPs) by deriving the governing equations. The accuracy of the model was verified by performing a series of FUS experiments on phantoms embedded with NPs. This was the first study that fully elucidated the physics and mathematics behind the FUS treatment in the presence of NPs as therapeutic agents. My contribution to developing an analytical model for FUS was published in IEEE Transactions on Biomedical Engineering (IF: 4.538), one of the most competitive and prestigious journals in the field of biomedical engineering.

One promising strategy to increase the thermal efficiency of FUS is to employ nanoparticles (NPs) as ultrasound agents for the hyperthermia procedure. However, the interaction mechanism between NPs and ultrasonic waves has not been well understood. In an effort to investigate the heating process of NPs-enhanced FUS, I derived a set of FUS equations governing the temperature variation during the thermal ablation based on the principle of conservation of energy for heat transfer mechanism. A numerical model was developed to solve the FUS equations to simulate the absorption mechanism of FUS in the presence of NPs, the consequent heat transfer process, and the temperature rise profile during the sonication period. The accuracy of the numerical model was verified by performing a series of experiments on tissue-mimicking phantoms embedded with magnetic NPs (MNPs). The transport processes taking place at the boundaries between NPs and the surrounding medium played a major role in the temperature rise during FUS sonication. Besides, the effects of MNPs on rising temperature were improved by amplifying the ultrasonic power and frequency as well as by increasing the MNP concentration. A quantitative comparison with experimental results demonstrated the potential of the numerical model to accurately predict the heating mechanism of FUS mediated by NPs.

Physics: The interaction mechanism between ultrasonic waves and embedded NPs, leading to higher wave absorption.

Mathematics: Derivation of governing equation based on the principle of conservation of energy for heat transfer

Governing equation for heat transfer procedure during NP-enhanced FUS

Analytical modeling of NP-enhanced FUS by solving the governing equations 

The accuracy of the model was verified by performing a series of FUS experiments on phantoms embedded with NPs