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A comparison between transport and diffusion calculations using a finite element‐spherical harmonics radiation transport method
Author(s) -
Aydin E. D.,
de Oliveira C. R. E.,
Goddard A. J. H.
Publication year - 2002
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.1500404
Subject(s) - photon transport in biological tissue , spherical harmonics , heavy traffic approximation , photon diffusion , vector spherical harmonics , photon , convection–diffusion equation , computational physics , scattering , physics , finite element method , anisotropy , radiation transport , isotropy , diffusion equation , diffusion , harmonics , radiation , void (composites) , neutron transport , optics , monte carlo method , mechanics , materials science , mathematics , quantum mechanics , dynamic monte carlo method , economy , voltage , service (business) , direct simulation monte carlo , composite material , thermodynamics , light source , statistics , neutron , economics
Most researchers choose the diffusion approximation to the transport equation as the model to describe photon migration in biological tissues. However, the applicability of this approximation is limited and, in certain cases, invalid. In this paper we introduce a two‐dimensional, finite element‐spherical harmonics (FE‐ P N ) radiation transport method for the simulation of light propagation in tissue. The propagation of light is investigated first in a layered cylinder, which can be seen as a very simplistic approximation of a human head. Effects of the anisotropy factor g on the photon migration is then examined in homogeneous and heterogeneous media for different values of g and μ s . The influence of void‐like heterogeneities and channels in which absorption and scattering are very small compared with the surrounding medium on the transport of photons is also investigated. Significant differences between transport and diffusion calculations are shown to occur in all cases.