Millimetre wave radiation interacts with the human body down to a depth of around half a millimetre into the skin at 100 GHz; less than this depth at higher frequencies, with greater penetration at lower frequencies. Interaction is exclusively with the skin, including the first layers of living tissue, and is therefore the ideal probe for the largest organ of the human body.
Spatial resolutions of measurements are down to half a wavelength in the skin, so range from 0.1 mm to 5 mm.
The medical applications of millimetre wave sensing technology are relatively undeveloped, mainly due to the subtlety of signatures and the absence of commercially available systems that generate high quality calibrated data. Likely applications are those associated with the early diagnosis of: skin cancers, skin moles, Raynaud's disease, psoriasis, scleroderma, eczema and diabetic (foot and leg) ulcers.
Moving to lower frequencies around 10 GHz will enable penetration to ~2 mm enabling signatures to be measured associated with circulatory disorders.
Potentially these measurements could be made of the whole of the human body in a period of seconds, enabling a new type of whole body screening. Periodic measurements may identify precursors of developing disorders, in or just under the skin.
Millimetre wave sensors to image specifically the human skin could complement existing systems (ultra-sound, CT, MRI, PET) that are used to monitor health and diagnose diseases and conditions in other parts of the body.
Currently no effective millimetre wave medical diagnostic systems exist, but a diversity of highly mature devices and subsystems exist from which a diagnostic could be developed to investigate the above conditions.