Propagation of low amplitude focused ultrasound waves in a bubbly medium: Finite element simulation and theoretical considerations for optimization of the treatment parameters

Administration of microbubbles (MBs) increases the attenuation and changes the sound speed (Cs) of the medium. These phenomena are nonlinear and depend on MB size frequency and acoustic pressure. The increased attenuation can shield the focal region and reduce the efficacy of the application (e.g., drug delivery). Detailed information on the attenuation and Cs in the medium is needed to optimize these applications. In this study, using our recently developed nonlinear model, the pressure dependent (PD) attenuation and Cs of a bubbly medium are calculated and classified in terms of the resonance frequency (fr) of the MBs for (0.5fr