TY - JOUR
T1 - Comparison of finite-difference transport and diffusion calculations for photon migration in homogeneous and heterogeneous tissues
AU - Hielscher, Andreas H.
AU - Alcouffe, Raymond E.
AU - Barbour, Randall L.
PY - 1998/5
Y1 - 1998/5
N2 - We analyse the limits of the diffusion approximation to the time- independent equation of radiative transfer for homogeneous and heterogeneous biological media. Analytical calculations and finite-difference simulations based on diffusion theory are compared with discrete-ordinate, finite- difference transport calculations. The influence of the ratio of absorption and transport scattering coefficient (μ(a)/μ'(s)) on the accuracy of the diffusion approximation are quantified and different definitions for the diffusion coefficient, D, are discussed. We also address effects caused by void-like heterogeneities in which absorption and scattering are very small compared with the surrounding medium. Based on results for simple homogeneous and heterogeneous systems, we analyse diffusion and transport calculation of light propagation in the human brain. For these simulations we convert density maps obtained from magnetic resonance imaging (MRI) to optical- parameter maps (μ(a) and μ'(s)) of the brain. We show that diffusion theory fails to describe accurately light propagation in highly absorbing regions, such as haematoma, and void-like spaces, such as the ventricles and the subarachnoid space.
AB - We analyse the limits of the diffusion approximation to the time- independent equation of radiative transfer for homogeneous and heterogeneous biological media. Analytical calculations and finite-difference simulations based on diffusion theory are compared with discrete-ordinate, finite- difference transport calculations. The influence of the ratio of absorption and transport scattering coefficient (μ(a)/μ'(s)) on the accuracy of the diffusion approximation are quantified and different definitions for the diffusion coefficient, D, are discussed. We also address effects caused by void-like heterogeneities in which absorption and scattering are very small compared with the surrounding medium. Based on results for simple homogeneous and heterogeneous systems, we analyse diffusion and transport calculation of light propagation in the human brain. For these simulations we convert density maps obtained from magnetic resonance imaging (MRI) to optical- parameter maps (μ(a) and μ'(s)) of the brain. We show that diffusion theory fails to describe accurately light propagation in highly absorbing regions, such as haematoma, and void-like spaces, such as the ventricles and the subarachnoid space.
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U2 - 10.1088/0031-9155/43/5/017
DO - 10.1088/0031-9155/43/5/017
M3 - Article
C2 - 9623656
AN - SCOPUS:0031901460
SN - 0031-9155
VL - 43
SP - 1285
EP - 1302
JO - Physics in Medicine and Biology
JF - Physics in Medicine and Biology
IS - 5
ER -