Compact tissue oximeter based on dual-wavelength multichannel time-resolved reflectance

We developed a compact dual-wavelength multichannel tissue oximeter based o n the time-correlated single-photon counting (TCSPC) technique. The light s ources are two pulsed diode lasers (output wavelengths of 672 and 818 nm, a n average power of 1 mW, a pulse duration of 100 ps, and a pulse-repetition rate as high as 80 MHz). The time-resolved reflectance photons are detecte d by a multianode photomultiplier, and the output signals are redirected by a router to different memory blocks of the TCSPC personal computer board. The system's accuracy in determining the absorption mu(alpha) and the reduc ed-scattering mu(s)' coefficients and in reconstructing absorber concentrat ions in diffusive media was tested on phantoms. Preliminary in vivo tissue- oxygenation measurements were performed on healthy volunteers under differe nt physiological conditions with a minimum acquisition time of 100 ms and a n injected power of less than 100 mu W. (C) 1999 Optical Society of America .