Experimental Validation of k-Wave: Nonlinear Wave Propagation in Layered, Absorbing Fluid Media

Computational modelling, full-wave modelling, model checking, model validation, pressure measurement, ultrasonic transducers.

Models of ultrasound propagation in biologically relevant media have applications in planning and verification of ultrasound therapies and computational dosimetry. To be effective, the models must be able to accurately predict both the spatial distribution and amplitude of the acoustic pressure. This requires that the models are validated in absolute terms, which for arbitrarily heterogeneous media should be performed by comparison with measurements of the acoustic field. In this study, simulations performed using the open-source k-Wave acoustics toolbox were quantitatively validated against measurements of acoustic pressure in water and heterogeneous absorbing fluid media. In water, the measured and simulated spatial peak pressures agreed to within 3% under linear conditions, and 7% under non-linear conditions. After propagation through a planar or wedge shaped glycerol filled phantom, the difference in spatial peak pressure was 7% and 6% respectively. These differences are within the expected uncertainty of the acoustic pressure measurement. The -6 dB width and length of the focus agreed to within 3% in all cases, and the focal positions were within 0.1 mm for the planar phantom and 1.1 mm for the wedge shaped phantom. These results demonstrate that when the acoustic medium properties and geometry are well known, accuarate quantitative predictions of the acoustic field can be made using k-Wave.