A technique developed by engineers at the California Institute of Technology (Caltech) enables researchers to focus light efficiently inside biological tissue. While the previous limit for how deep light could be focused was only about one millimeter, the Caltech team is now able to reach 2.5 millimeters. With future improvements in optoelectronic hardware used to record and play back light, the engineers say they may be able to reach 10 cm (almost 4 inches) — the depth of ultrasound – within a few years.
The technique is used much like a flashlight shining on the body's interior, and may eventually provide researchers and doctors with a host of possible biomedical applications, such as a less invasive way of diagnosing and treating diseases. Cranking up the power of light could even allow this technology to replace the traditional scalpel for “incision-less surgery,” researchers said.
This method could also be used with fluorescence imaging. The researchers embedded a patch of gel with a fluorescent pattern that spelled out “CIT” inside a tissue sample. Then, they scanned the sample with focused light beams. The focused light hit and excited the fluorescent pattern, resulting in the glowing letters “CIT” emanating from inside the tissue. The team also demonstrated their technique by taking images of tumors tagged with fluorescent dyes.
Doctors might also someday use this process to treat cancer with photodynamic therapy. In this procedure, a drug that contains light-sensitive, cancer-killing compounds is injected into a patient. Photodynamic therapy is now only used at tissue surfaces, because of the way light is easily scattered. The new technique should allow doctors to reach cancer cells deeper inside tissue.
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Also: Read about a miniaturized laser diode solution that was developed for the medical market.
