Spotting the signs

Researchers at the National Physical Laboratory (NPL) have developed a new means to ensure that a screening technique using Optical Coherence Tomography (OCT) systems can be relied upon by clinicians so that they can accurately spot early signs of cancer.

OCT is an increasingly popular method for looking beneath the surface of certain materials, notably human tissue. Although it can only be used to image tissue at depths of a few millimetres, it can produce higher-resolution images than either MRI or ultrasound, making it suitable for detecting changes in tissue structure that can indicate the early stages of cancer.

Indeed, OCT systems such as those from Orpington Kent-based Michelson Diagnostics have already proven capable of imaging microstructures in living tissue in real time at depths of 1mm or more at a resolution of less than 10µm.

In a simple OCT system, a source of light from a laser is separated into two beams by a Michelson interferometer — one beam is focused on a sample through a lens and the other half is directed towards a reference mirror. The light reflected from the mirror and from the sample is then sent to a detector that measures the degree of interference between the two sources. The signal from the detector is then processed and used to create a spatial reflectivity map of the sample that contains both depth and intensity information.