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Biomedical researchers have been excited about the surgical potential of laser pulses for years. But what they've been missing is a practical laser scalpel that can deliver the pulses - which last less than a trillionth of a second - inside the body.
Now Adela Ben-Yakar and colleagues at the University of Texas at Austin have developed a pulsing laser small and flexible enough to fit on the end of an endoscope like those used to examine the colon or stomach.
Short pulses are attractive for precision laser surgery because they concentrate their energy into a very small volume of tissue, so they remove a surface layer but leave lower layers or adjacent cells undamaged. The pulses have even been used to perform surgery on individual cells, primarily for research to study how cells operate.
It usually takes a big laser to produce a tiny pulse lasting only 200 femtoseconds, or 200 millionths of a billionth of a second - although the light pulse itself stretches only 60 micrometres. Earlier versions of the optical scalpel that is needed to focus the light precisely on the desired spot were about 18 millimetres in diameter, impractically large for insertion into body orifices.
Ben-Yakar's team designed a scalpel only 9.6 mm wide and 23 mm long that focuses light onto a spot 20 per cent smaller than before. "All the optics we tested can go into a real endoscope," says Ben-Yakar. "The probe has proven that it's functional and feasible and can be [manufactured] commercially." Team member Christopher Hoy will describe it next week at the Conference on Lasers and Electro-Optics(CLEO) in San Jose, California.
Tabletop femtosecond lasers now perform surgery on the surface of the eye, but Ben-Yakar says the endoscope-mounted laser scalpel could be used inside the body to remove small tumours or repair damaged vocal cords. She also is exploring other possibilities for what she calls "next-generation clinical tools for microsurgery". Although the new design is ready for manufacture, it will require at least five years of clinical tests before it can be certified for human use by the US Food and Drug Administration.