Spectral dependence of temporal point spread functions in human tissues.
We have determined the spectral dependence of the temporal point spread functions of human tissues experimentally between 740 and 840 nm in transmittance measurements on the adult head, forearm, and calf (in vivo) and the infant head (post mortem) by using picosecond laser pulses and a streak camera detector. two parameters are extracted from the temporal point spread function; the differential path-length factor (dpf), calculated from the mean time, and the slope of the logarithmic intensity decay. in all tissues the dpf and the logarithmic slope show a reciprocal relationship and exhibit characteristics of the absorption spectra of hemoglobin. the dpf falls with increasing wavelength, the variation beingtypically 12%, while the logarithmic slope increases with wavelength. a quantitative analysis of the logarithmic slope spectrum significantly underestimated expected tissue chromophore concentrations. the absolute magnitudes of the dpf s owed considerable intersubject variation, but the variation with wavelength was consistent and thus may be used in the correction of tissue attenuation spectra. © 1993 Optical Society of America.
|Title:||Spectral dependence of temporal point spread functions in human tissues|
|UCL classification:||UCL > School of BEAMS
UCL > School of BEAMS > Faculty of Engineering Science
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