Computational aspects in high intensity ultrasonic surgery planning.

Area of Science:

• Medical Physics
• Biomedical Engineering
• Acoustics

Background:

• Therapeutic ultrasound requires precise treatment planning for effective and safe tissue heating.
• Computational modeling plays a vital role in simulating ultrasound propagation and thermal deposition.
• Nonlinear acoustic effects can significantly influence energy deposition patterns during focused ultrasound treatments.

Purpose of the Study:

• To review computational aspects of therapeutic ultrasound treatment planning.
• To investigate the impact of nonlinear ultrasound propagation on thermal dose calculations.
• To assess the accuracy of combined frequency domain Rayleigh and KZK models for simulating focused ultrasound heating in muscle tissue.

Main Methods:

• Nonlinear ultrasound simulations using a combined frequency domain Rayleigh and KZK model.
• Integration of ultrasonic simulations with thermal simulations to compute in vivo muscle tissue heating.
• Comparison of simulation results with experimental measurements for focused ultrasound transducers with varying F-numbers.

Main Results:

• Simulations showed good agreement with measurements for large F-number transducers.
• Simulated temperature rise was approximately double the measured values for an F# 1.9 transducer.
• Nonlinearities in coupling water and inclusion of skin significantly impacted accuracy, with water nonlinearities enhancing focal temperature by over 100%.

Conclusions:

• Nonlinear propagation is critical for accurate energy distribution in focused ultrasound treatments and should be included in planning.
• Pulsed high-power sonications may reduce treatment times by up to 3x.
• Current simulation models require further development for improved accuracy with sharply focused transducers.