Development of Water Content Dependent Tissue Dielectric Property Models

Area of Science:

• Biophysics
• Biomaterials Science
• Medical Physics

Background:

• Water content significantly influences biological tissue dielectric properties.
• Dehydration effects from thermal heating on tissue properties are not fully understood.
• Accurate dielectric models are crucial for microwave-based medical applications.

Purpose of the Study:

• To develop and validate dielectric tissue property models dependent on water and air content.
• To cover the microwave frequency range (1-15 GHz).
• To improve accuracy in simulating microwave ablation and personalize treatment planning.

Main Methods:

• Combined Maxwell-Fricke mixture theory with a four-pole Cole-Cole equation.
• Coupled a Maxwell mixture model with a Debye function.
• Tested models on bovine liver and swine lung tissues at varying hydration and inflation states.

Main Results:

• Both proposed models accurately predicted permittivity (ε') and conductivity (σ) from 1-15 GHz.
• The Maxwell-Debye model required fewer assumptions and showed higher accuracy ( < 15% mean percent error).
• Models successfully characterized dielectric properties under different tissue conditions.

Conclusions:

• Dielectric models incorporating water and air content are effective for microwave frequencies.
• The Maxwell-Debye model offers a more accurate and less assumption-dependent approach.
• These models can enhance microwave ablation simulations and support personalized medicine.