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The Biomedical Photonic Imaging department has developed an entirely painless method of screening for breast cancer and of determining the nature of vascular birthmarks (‘port wine stains’). These are two very different applications of the same technology: photoacoustic imaging. In essence, light goes into the body and sound comes out.

Photoacoustic imaging involves directing short but powerful bursts of laser light onto the patient's body. When the laser beam strikes a blood vessel, the light is transformed into heat. A minuscule rise in blood temperature (imperceptible to the patient) increases the pressure within the blood vessel very slightly, which sends a soundwave through the body. This soundwave can be detected by small microphones placed against the skin.

The researchers of Biomedical Photonic Imaging have identified various practical applications for this technology. It can, for example, be used to determine the nature of vascular birthmarks, commonly known as 'port wine stains', which in many cases can then be removed using other forms of laser therapy.

However, it is in curative medicine that the opportunities are greatest. One very promising new application is the photoacoustic mammograph for use in breast cancer screening. The conventional technique causes considerable discomfort to the patient, whose breast must be clamped between two plates in order to make an X-ray photo. The combination of laser and sound is entirely painless, and carries none of the risks associated with radiation. In future, doctors will only have to listen to the way in which blood vessels respond to the laser stimulus.

Painless breast cancer screening using photoacoustic imaging (from 3: 20)