Patent ID: 6246892
Filing Date: 2001-06-12
Classification: A61B,G01N

Abstract:
An in vivo spectroscopic method for quantifying concentration of an absorptive pigment in biological tissue comprising:positioning an input port at a selected location relative to the biological tissue;positioning a detection port at another location spaced at a selected distance of several centimeters from said input port;generating a first carrier waveform of a selected frequency on the order of 10.sup.8 Hz;introducing into the tissue at said input port electromagnetic radiation of at least two selected wavelengths modulated by said carrier waveform, at least one of said wavelengths being sensitive to concentration of said absorptive pigment present in the tissue, said tissue exhibiting a similar scattering property at said wavelengths;detecting at said detection port the radiation that has migrated over migration paths in a portion of the tissue from said input port, said detected radiation having wavelengths which are the same as said at least two wavelengths introduced to the tissue;creating a first and a second reference phase signals of predefined substantially different phases;comparing, at each wavelength, said detected radiation with said first and said second reference signals and determining therefrom a real output signal and an imaginary output signal, at each wavelength, respectively;providing said scattering property of said portion of the tissue; andquantifying concentration of said absorptive pigment in said portion of said tissue.