A wavelength-scanning technique could allow diagnosis and treatment with one instrument when confocal microscopy is introduced into an endoscope. Researchers at Massachusetts General Hospital have developed a way to introduce confocal microscopy into the endoscope. If the technique is successful for the long term, pathologists could be working in the operating room with surgeons to allow concurrent diagnosis and treatment of cancer. Confocal microscopy, which is relatively new in clinical medicine, is especially useful because it optically sections target tissue. This ability and the ability to image cells and subcellular components are critical to diagnosis and staging cancer, says Caroline Boudoux, of the Harvard-Massachusetts Institute of Technology (MIT) division of health sciences and technology graduate student performing research in the optical diagnostics group of Drs. Brett E. Bouma and Gary J. Tearney at the hospital's Wellman Center for Photomedicine. Confocal microscopy, which requires a method of raster scanning a laser spot across the target, captures light or fluorescence through a pinhole aperture. light scattered from the outside of the focal plane is scattered. To put such a setup into an endoscopy has proved to be difficult in other efforts, but Boudoux and her colleagues propose a solution that eliminates the need for a mechanism that steers the laser beam in two directions to scan the sample. Instead, they suggest use of a wavelength-tunable laser and diffraction grating in a method called spectrally encoded confocal microscopy. In a demonstration, a combination of described components allowed the scientists to quickly sweep the wavelength across a 70nm band and to sweep the imaging spot in a line across the x-axis of the focal plane. In testing the system on a standard resolution chart from the U.S. Air Force, the scientists found that the system could clearly resolve the smallest lines on the chart which are 2.2 mu m apart. Several other tests are described. The group will continue work on a handheld probe that will widen the range of clinical applications.