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The diffuse correlation spectroscopy (DCS) and diffuse near infrared spectroscopy (DNIRS) are the contemporary non-invasive optical methods which have turned out now to be ones of the most required optical tools for assessing tissue health, in regards to mammography, brain, and deep tissue injury. Earlier we reported on an observation, within the DCS technics, of development of pressure injuries measuring dermal and subcutaneous red blood cell motion; the data obtained has produced remarkably a characteristic decay time of the light intensity temporal correlation function being five times larger for patients of the group with developing open pressure injuries as compared with the group exhibiting healthier stage. The quantitative determination of the characteristic time required a definite picture of scatterer motion. For quantitative study the crucial problem to solve is a proper account for the scattering anisotropy. We perform comparative simulations of the diffuse photon density wave (DPDW) signals and the temporal intensity correlation functions either with the Henyey-Greenstein (HG) or Rayleigh-Gans (RG) phase functions, which we consider is more appropriate as the hard sphere suspension model for imitating a tissue. We find that for a half space geometry the results obtained for these two scattering patterns turn to be quite close; however for finite size tissue geometries results of simulations of the source-detector plot for backscattered intensity differ noticeably at small distances; simulating the temporal correlation function with these two phase functions we find the blood flow to be different for different scattering patterns in case of spatial restrictions. The DPDW methodology is widely used in a number of biomedical applications. Here we present results of Monte Carlo simulations that employ an effective numerical procedure, based upon a description of radiative transfer in terms of the Bethe-Salpeter equation, and compare them with measurements from Intralipid aqueous solutions. We find the Monte Carlo simulations and measurements to be in a very good agreement for a wide range of source-detector separations.
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