Experimental investigation of the mammary gland tumour phantom for multifrequency microwave radio-thermometers.

Microwave radiometry is a spectral measurement technique for resolving the electromagnetic radiation of matter when its temperature is above absolute zero. The radio-thermometer utilises this technique and consequently can provide temperature distributions in subcutaneous biological tissues. A new phantom was proposed that imitates a mammary gland tumour, and the brightness temperature was observed using radio-thermometers operated at different frequencies, 1.75GHz and 3GHz. The proposed phantom, simulating heat diffusion propagated by tissues around real tumours, revealed that the thermal characteristics of the tumour imitator were well matched to the heat transfer properties of a real tumour and a proportional linear relationship between the location of the tumour imitator and the brightness temperature in a homogenous medium was established. From experiments using the proposed mammary gland tumour phantom and a clinical trial on patients with breast cancer, it could be concluded that a radio-thermometer with a short wavelength (lambda = 10cm, i.e. f= 3GHz) is useful to resolve a thermal anomaly at a shallow depth in an homogenous medium such as a breast.