Scientists have developed a new camera that can see through the human body.
The device is designed to help doctors track medical tools known as endoscopes, which are used to investigate a range of internal conditions.
Until now, it has not been possible to track where the kit is without using X-rays or other expensive methods.
The new camera can detect sources of light inside the body, such as the illuminated tip of the endoscope's long flexible tube.
Professor Kev Dhaliwal, of the University of Edinburgh, said: "It has immense potential for diverse applications such as the one described in this work.
"The ability to see a device's location is crucial for many applications in healthcare, as we move forwards with minimally invasive approaches to treating disease."
Early tests have shown the prototype device can track a point light source through 20 centimetres of tissue under normal conditions.
Beams from the endoscope can pass through the body but usually scatter or bounce off tissues and organs rather than travelling straight through.
It means it is extremely difficult to get a clear picture of where the tool is.
The new camera can detect individual particles, called photons, and is so sensitive it can catch tiny traces of light passing through tissue.
It can also record the time taken for light to pass through the body, meaning the device is able to work out exactly where the endoscope is.
Researchers have developed the new camera so it can be used at the patient's bedside.
The project - led by the University of Edinburgh and Heriot-Watt University - is part of the Proteus Interdisciplinary Research Collaboration, which is developing a range of new technologies for diagnosing and treating lung diseases.
