Dielectric and thermal properties of phantoms for electromagnetic based hyperthermic technologies

Abstract

Hyperthermia, a therapeutic technique used in cancer treatment, relies on the precise heating of target tissues to enhance the effectiveness of radiotherapy or chemotherapy. To achieve this, electromagnetic (EM)-based hyperthermic technologies require accurate simulation of human tissue properties under hyperthermia conditions (40–48°C). However, existing tissue-mimicking phantoms face limitations, particularly at higher temperatures, hindering reliable testing of hyperthermia devices. This dissertation addresses this challenge by developing phantoms that replicate the dielectric and thermal properties of skin, fat, muscle, and tumour tissues at temperatures up to 50°C. This work improves the semi-solid phantom recipe proposed by Lazebnik et al. (2005) by replacing the gelling agent gelatine with agar-agar, thereby increasing the melting point while maintaining tissue-like behaviour. Additionally, the project will provide a thorough characterisation of the dielectric and thermal properties of these phantoms, ensuring they closely match the electromagnetic and thermal properties of real tissue across a range of frequencies and temperatures. The modified agar-based phantoms demonstrate successful replication of real tissue properties under hyperthermia conditions, exhibiting less than 20% deviation from literature values. This confirms their validity for precise laboratory evaluation of electromagnetic (EM)-based medical devices, particularly for hyperthermia treatment planning and device calibration. By developing these phantoms, this research aims to enable the accurate testing and optimisation of EM-based hyperthermic devices in the laboratory, reducing the need for extensive preclinical trials and accelerating the transition to clinical validation. This work has the potential to significantly improve the safety and efficacy of hyperthermic technologies, ultimately contributing to better outcomes in cancer treatment and other medical applications.