Title:
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Non-linear modelling of microwave soft-tissue ablation using the finite element method
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Reliable and accurate information regarding the heat distribution inside biologica.I tissue
due to microwave thennal ablation is essential for the design and optimization of safe
therapeutic applicators and for the development of experiments, which aim to
investigate their effects.
To date, very few finite element models (FEM) have been developed to describe and
illustrate electric field penetration, specific absorption rate (SAR) and temperature
distribution in biological tissue due to microwave ablation probes. A coupled field
finite elemerit analysis model that accounts for the temperature dependent conductivity
and blood perfusion changes has not, as yet, been developed for ablation type devices.
Although it is widely acknowledged that accounting for temperature dependent
phenomena may affect the outcome ofthese models, the effect has not yet been assessed
for microwave tumour ablation (MTA).
This thesis aims to develop an improved non-linear coupled field electromagnetic and
thermal FE model of microwave ablation, incorporating temperature dependent
electrical and thermal properties of, ex-vivo bovine liver. Measurements of temperature
dependent ex-vivo bovine liver electrical permittivity are made and their effect.
presented. Temperature dependent thennal properties of the tissue are limited. to
temperatures below phase change. Therefore, a theoretical tissue model for going
changes in phase is also presented. The FE model of microwave ablation is based on a
2.45 GHz minimally invasive dielectric loaded monopole antenna
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