Modeling the Physics of Bubble Nucleation in Histotripsy

Area of Science:

• Acoustics
• Thermodynamics
• Biophysics

Background:

• Histotripsy relies on bubble nucleation for tissue ablation.
• Existing models lack comprehensive thermodynamic understanding of nucleation under histotripsy conditions.

Purpose of the Study:

• To develop a theoretical framework for modeling bubble nucleation in histotripsy.
• To elucidate the thermodynamic principles governing ultrasound-induced bubble formation.

Main Methods:

• Phenomenological adaptation of classical nucleation theory.
• Parametrization using histotripsy experimental data and a temperature-dependent activity factor.
• Simulations of histotripsy pressure and temperature fields.

Main Results:

• A unified model harmonizing predictions with experimental data across temperatures.
• Identification of key roles for ultrasound frequency, waveforms, peak focal pressures, and duty cycle.
• Significant nucleation rates observed at -30 MPa below 50 °C; a 20-order magnitude increase in nucleation rates between 60 °C-100 °C at -15 MPa.

Conclusions:

• The developed framework provides thermodynamic insights into bubble nucleation in histotripsy.
• Understanding these nucleation dynamics is vital for optimizing histotripsy treatment parameters.
• This work advances the theoretical basis for controlling histotripsy-induced cavitation.