Abstract

The photoacoustic guided (PAG) technique can noninvasively increase light penetration and localization in deep tissue. The mechanism of the PAG technique is considered to be a pressure dependent refractive index change caused by acoustic wave that produces a virtual waveguide, but it is still a highly controversial issue. In this study, light propagation in the models with the PAG region was calculated by a Monte Carlo simulation. We assumed that the change in the refractive index or anisotropy factor of scattering in the PAG region contributes to the light guiding effect. Both the refractive index and anisotropy factor heterogeneities increase the photon density in the PAG region of the deep tissue part. The effect of localization of the photon density in the PAG region with the anisotropy factor heterogeneity is less significant compared to that with the refractive index heterogeneity.

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