Quantitative thermal imaging

Abstract

The association between temperature and disease is centuries old. Clinical thermology was established by Wunderlich, in 1851, who systemically recorded oral temperature with one of the first thermometers capable of reproducible measurement. Thermal imaging is highly developed with contemporary infrared imaging systems having thermal and spatial resolution far in excess of the earlier systems of the 1960s. Real time imaging, together with efficient on-line processing, has greatly improved the ease of use and quality of information. Microwave energy also forms a (smaller) part of the body's natural reactive heat loss. Research into natural microwave detection has shown that 3 GHz and 212 GHz energy can be measured. At the former wavelength a deeper source of thermal energy is measured; the actual depth varies with the characteristics of the superficial tissues, but may be up to several centimetres below the skin. The technology is a long way behind that of infrared systems, but nevertheless microwave thermography has an interesting future.