Microwave Tomography, also known as Passive Microwave Imaging is a type of imaging technique similar to that seen in Thermography but utilises the properties of microwaves to produce clear maps of heat distributed throughout the body

This scan is non-invasive so doesn’t require surgery, and has been used mostly for breast tissue scanning as an alternative to mammography, a form of Radiography, using X-rays.

Microwave Tomography

What is it?

How does it work?

The techniques used do not require any external energy sources and so produce small energy changes only capable of making 0.1% of a cup of tea.

Image Source (Chalmers)

Some of the natural heat radiated from the body is in the form of Microwaves. The body part to be analysed, usually the breast, is placed into an ellipse-shaped cavity which is lined with reflective metal called Nickel. The microwaves produced by the body bounce from wall to wall of the cavity and its ellipse shape causes these microwaves to focus at one point where they can be collected by a device called a Microwave Antenna which focusses the microwave signal and sends it into a detector where the signal can be displayed as a heat map image of the analysed tissues. [MW5].

This radiometer is tuned like a radio to detect certain frequencies of microwaves until it can form an entire image. There will be differences in the microwaves received which corresponds to a change in temperature between tissues. The radiometer is sensitive to a change in temperature (divergence) of 0.7°C [MW6].

Safety

This technique can be used as a safe, early-detection method for breast cancer and with further research will hopefully replace its more harmful counterpart the X-ray Mammogram which uses ionising radiation.

This technique uses passive imaging and so only analyses the naturally occurring energy in your body, therefore there is only a small amount of energy used in the process. 80 Joules to be precise - which is equivalent to the energy needed to make 0.1% of a cup of tea, that's almost nothing!

A top view showing how the microwaves are focussed by the ellipse-shaped cavity.