Nonlinear acoustic beam propagation modeling in dissipative media

Abstract

Accurate simulation of an intensive ultrasound beam requires taking nonlinear propagation effects into account. A notable example in the field of biomedical ultrasound where the effect of nonlinearity may play a significant role is the high intensity focused ultrasound (HIFU) as a non-invasive energy-based treatment modality. In this work, a 3D numerical model to simulate nonlinear propagation of continuous wave ultrasound beams in dissipative homogeneous tissue-like media is presented. The model implements a second-order operator splitting method in which the effects of diffraction, nonlinearity and attenuation are propagated over incremental steps. The model makes use of an arbitrary 3D source geometry definition method and a non axi-symmetric propagation scheme, which leads to a 3D solution to the resulting nonlinear ultrasound field. This work builds on methods developed by Tavakkoli et al. (1998) and Zemp et al. (2003) and offers an efficient way to calculate nonlinear field of continuous wave ultrasound sources. The proposed model is a particularly useful computational tool in carrying out simulations of high intensity focused ultrasound beams in soft tissue where the effects of nonlinearity, diffraction, and attenuation are important. The model was validated through comparisons with other established linear and nonlinear numerical models as well as published experimental data.