Self-tuning fuzzy logic control for ultrasound hyperthermia with reference temperature based on objective functions

Area of Science:

• Biomedical Engineering
• Therapeutic Ultrasound
• Control Systems

Background:

• Focused ultrasound (FUS) hyperthermia offers precise tumor treatment.
• Effective temperature control is crucial for FUS hyperthermia efficacy and safety.
• Variations in blood perfusion significantly impact temperature distribution during treatment.

Purpose of the Study:

• To develop and evaluate a self-tuning fuzzy logic controller for scanned focused ultrasound hyperthermia.
• To determine the reference temperature (Tr) using objective functions for optimized heating.
• To enhance controller adaptability to blood perfusion variations.

Main Methods:

• Simulations were used to model power deposition and temperature profiles via the bioheat transfer equation.
• A fuzzy logic control algorithm determined output power levels.
• An observer was integrated to account for blood perfusion variations.
• Objective functions evaluated temperature profile appropriateness.

Main Results:

• The controller rapidly heated and maintained tumor regions at target temperatures, even with fluctuating blood perfusion.
• Temperature profiles, objective function values, and power levels correlated with blood perfusion.
• Controller performance was largely independent of thermosensor location and initial reference temperature settings.

Conclusions:

• The developed fuzzy logic controller effectively manages temperature distribution in FUS hyperthermia.
• Objective function-based reference temperature tuning enables precise thermal control.
• This control strategy optimizes temperature fields during treatment without requiring exact sensor location or initial Tr knowledge.