Imaging the 3D temperature distributions caused by exposure of dielectric phantoms to high-frequency electromagnetic fields

A new method of measuring the temperature distribution due to high frequency electromagnetic field (HF-EMF) power absorption is established. The method is applied to the measurement of the spatial distribution of specific absorption rate (SAR) in tissue exposed to HF-EMF. A microencapsulated thermotropic liquid crystal (MTLC) is employed as the temperature probe because of high resolution and high sensitivity. A high-molecular gel phantom with a high transparency and a high viscosity is developed to realize visualization technique with MTLC. The complex permittivity of the phantom is adjusted to that of muscle at 900 MHz and 1.45 GHz. This method is proven to be efficient in visualizing HF-EMF power absorption by exposure experiment. Index Terms--Specific absorption rate (SAR), 3D temperature measurement, thermotropic liquid crystals, high frequency energy absorption, biological effect, dosimetry, phantom