A model for the time dependent three-dimensional thermal distribution within iceballs surrounding multiple cryoprobes

Area of Science:

• Biomedical Engineering
• Computational Modeling
• Cryosurgery

Background:

• Cryoprobes are used in cryosurgery to destroy unwanted tissue.
• Accurate modeling of iceball formation is crucial for optimizing cryosurgical procedures.
• Understanding thermal gradients and iceball dynamics is key to predicting treatment efficacy.

Purpose of the Study:

• To develop and validate a time-dependent, 3D finite difference model for iceball formation around multiple cryoprobes.
• To predict thermal histories and calculate the ablative ratio for various cryoprobe configurations.
• To assess the impact of probe number and cooling rates on cryosurgical outcomes.

Main Methods:

• Developed a 3D finite difference model incorporating realistic cryoprobe geometry and longitudinal thermal gradients.
• Simulated iceball formation for 1, 3, and 5 cryoprobe configurations.
• Validated model predictions against experimental data for thermal histories.
• Calculated the ablative ratio (volume of critical isotherm / total iceball volume) at assumed critical temperatures (-20°C and -40°C).

Main Results:

• The model accurately predicted thermal histories within experimental error for multiple probe configurations.
• The ablative ratio for a single probe decreased over time.
• Multiple probe configurations showed an initial increase in the ablative ratio, followed by a plateau.
• Maximum ablative ratios of 0.55 (3 probes, -20°C) and 0.3 (5 probes, -40°C) were observed.

Conclusions:

• The developed 3D model provides accurate predictions of iceball formation and thermal dynamics.
• Multiple cryoprobe configurations significantly enhance the ablative ratio, suggesting improved efficacy in cryosurgery.
• The model serves as a valuable tool for optimizing cryoprobe placement and cooling parameters for enhanced tissue ablation.