Keeping tabs on where a medical scope is when inside a human body often relies on the skill of the doctor performing the procedure or expensive imaging technologies, such as X-rays. A team at the University of Edinburgh has now developed a camera that can detect traces of light from the tip of an endoscope through up to 20 cm (7.8 in ) of tissue, making it easier to guide them to the desired location.

The deeper a scope is inside the human body, the more its photons of light are scattered by bouncing off tissue. The University of Edinburgh discovered that two types of photons were found to escape the body's tissue with only a low level of scattering. Known as "ballistic and snake" photons, these particles of light can be isolated by using specific time-sensitive single-photon detectors.

By focusing in on those low-level scattered photons and ignoring the others, the team successfully developed a camera prototype that can identify a medical device with an accuracy of within 1 cm (0.4 in).

On the right is what a traditional camera picks up when trying to image the scattered light from a scope within the lung, while on the left is the newer system detecting the precise tip of the scope(Credit: University of Edinburgh)

The camera proved successful in detecting the location of a scope inside sheep lungs, but the team further investigated the device's penetration through a human body. The scope was placed on the back of a torso and imaging was performed from the front of the body, adding a human palm for extra depth. The camera took 17 seconds to generate an accurate image exposure.

The team believes that with more advanced detector arrays this exposure duration could be improved. The location accuracy could also be enhanced to within millimeters, and in the future offer real-time imaging of a medical device's location . But even with the current time delay and centimeter-scale imaging resolution the device is already appropriate for a variety of clinical endomicroscopy investigations of lung segments.

This innovation offers doctors a new way to approach non-invasive procedures, and as the technology is improved it could be applied to a variety of operations that traditionally involve more invasive surgery.

The new research was presented in the journal Biomedical Optics Express.

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