Researchers at the University of Michigan have taken a step towards using visible light to image inside the human body, using yoghurt and crushed glass.
Conducting the experiment, the researchers spelt "MICHIGAN" with a flashlight shone through yoghurt and crushed glass. The reason behind choosing these materials being, they scatter light in a similar way to human skin, and serve as a good model for tests. Their demonstration showed that they can take a quick scan of the material, as they would if imaging tissue inside the body.
While dense structures like bones show up clearly in x-rays, softer tissue like organs and tumours are difficult to make out. The reason being that x-rays are strongly deflected by bones, while they cut straight through soft tissue.
Visible light, on the other hand, is deflected and scattered by soft tissue. By understanding exactly how a patch of skin scatters the light, researchers hope to carefully pattern these light beams so that they can be focussed inside the body, which is a first step towards seeing into it.
"Light comes in, it hits a molecule, hits another, hits another, does something really crazy, and exits this way," said Moussa N'Gom, Assistant Research Scientist in Electrical Engineering and Computer Science and the first author on a study that explains the challenge of predicting the paths of individual light rays.
"Previous techniques used complex so-called holographic setups to extract the necessary information," said Raj Rao Nadakuditi, an Associate Professor of Electrical Engineering and Computer Science and a senior author on the study. The 'holographic method mentioned here untangled the scattering pattern by looking at how the light waves interfered with each other, which was precise yet a very slow process."We were able to achieve the same through simple brightness measurements and as a result, operate much faster," said Nadakuditi.
Keeping the current rate of development in mind, N'Gom anticipates that the first visible light images taken through skin could be seen within the next five years. The use of visible light would also be safer for diagnostic imaging than higher-energy x-rays.