* An infrared scanner converts the infrared radiation emitted from the skin to electrical impulses that are visualised in colour on a monitor. This 'thermogram' is a visual map of body temperature.
* The different colours indicate either an increase or decrease in infrared emissions from the body surface. Since there is a high degree of thermal symmetry in a healthy body, even subtle temperature asymmetries are easily spotted.
* Areas that show up as either too hot or too cold on the thermogram are noted as early-warning signs of something sinister in the underlying tissue (IEEE Trans Med Imaging, 1998; 17: 1019-27).
* As tumours emit more heat than the tissues surrounding them, and remain hot - or become even hotter - over time, thermal imaging is useful for detecting and tracking any early and suspicious changes.