Study on the influence of contact pressure on diffuse spectroscopy measurement of in vivo tissue

Abstract

Diffuse spectroscopy have been widely applied in biomedical researches and clinical diagnoses. The contact pressure induced by fiber optic probe may cause variability of in vivo diffuse spectrum measurement. In this paper, we study on the mechanism of contact pressure on diffuse spectrum measurement of in vivo tissue with finite element simulation model and in vivo experiment. The diffuse reflectance and transmittance spectrum of earlobe are measured under different contact pressure, which is used to investigate the influence of contact pressure and the optimal contact state for in vivo measurement. Both simulation and experiment results reveal that diffused transmittance spectra increased gradually, while, the diffused reflectance spectra decrease slightly with the increasing contact pressure. Firm pressure mainly influences on the volume of water and scattering properties within the tissue. However, the spectral measurements of in vivo tissue are insensitive to the contact pressure in range of 10-25kpa. That would be helpful for setup practical guidelines of clinical applications of in vivo diffuse spectroscopy measurement.