Fast Nonlinear Ultrasound Propagation Simulation Using a Slowly Varying Envelope Approximation.

Area of Science:

• Medical physics
• Acoustics
• Computational imaging

Background:

• Ultrasound simulations often use linear propagation, which is an approximation.
• Accurate simulation of nonlinear ultrasound wave distortion and harmonic generation is computationally intensive.
• Existing methods like the angular spectrum scheme are limited in harmonic computation due to quasi-linear approximations.

Purpose of the Study:

• To develop a fast and accurate simulation method for nonlinear ultrasound wave propagation.
• To compute the entire nonlinear distortion, including high harmonics and nonlinear mixing frequencies.
• To validate the proposed simulation approach against existing tools.

Main Methods:

• Utilized the slowly varying envelope approximation (SVEA) in the Fourier domain.
• Reduced derivative order using Fourier transform for computational efficiency.
• Implemented the simulator on a Graphics Processing Unit (GPU) for acceleration.

Main Results:

• The SVEA method accurately computes high harmonics and nonlinear mixing frequencies.
• Simulations showed low deviation and difference compared to other simulation tools, validating the approximation.
• The GPU-implemented simulator computes the full nonlinear distorted field in under 10 seconds.

Conclusions:

• The SVEA method provides a validated and efficient approach for simulating nonlinear ultrasound wave propagation.
• GPU acceleration significantly reduces computation time, making complex nonlinear simulations feasible.
• This fast simulation tool has implications for advancing medical ultrasound imaging and analysis.