NASA Photo #9709987:
The red light from the Light Emitting Diode (LED) probe shines through the fingers of Dr. Harry Whelan, a pediatric neurologist at the Children's Hospital of Wisconsin in Milwaukee. Whelan uses the long waves of light from the LED surgical probe to activate special drugs that kill brain tumors. Laser light previously has been used for this type of surgery, but the LED light illuminates through all nearby tissues, reaching parts of tumors that shorter wavelengths of laser light cannot. LED lights were originally developed by Quantum Devices Inc. of Barneveld, Wis., for commercial plant growht experiments aboard NASA's Space Shuttle.
Photo by Emmett Given, NASA Marshall Space Flight Center