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Proceedings Paper

Photon migration within the P3 approximation
Author(s): David A. Boas; Hanli Liu; Maureen A. O'Leary; Britton Chance; Arjun G. Yodh
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Paper Abstract

The diffusion approximation to the photon transport equation is the simplest model for photon migration. The applicability of the diffusion approximation, however, is limited. For example, it is strictly valid only when the absorption coefficient is small compared to the scattering coefficient and the source modulation frequency is small compared to the scattering rate. In this contribution we establish the theoretical range of validity of the diffusion approximation, review a frequency-dependent solution of the transport equation within the P3 approximation, and establish the significance of the P3 solution using Monte Carlo computer simulations. We find that the P3 approximation, in most cases, permits a more accurate determination of the optical properties of highly absorbing media as well as from data obtained at modulation frequencies greater than 3 GHz. Interestingly, for highly anisotropic scattering (g equals 0.9), we find that diffusion theory and the P3 approximation predict approximately the same values for the reduced scattering coefficient.

Paper Details

Date Published: 30 May 1995
PDF: 8 pages
Proc. SPIE 2389, Optical Tomography, Photon Migration, and Spectroscopy of Tissue and Model Media: Theory, Human Studies, and Instrumentation, (30 May 1995); doi: 10.1117/12.209973
Show Author Affiliations
David A. Boas, Univ. of Pennsylvania (United States)
Hanli Liu, Univ. of Pennsylvania (United States)
Maureen A. O'Leary, Univ. of Pennsylvania (United States)
Britton Chance, Univ. of Pennsylvania (United States)
Arjun G. Yodh, Univ. of Pennsylvania (United States)


Published in SPIE Proceedings Vol. 2389:
Optical Tomography, Photon Migration, and Spectroscopy of Tissue and Model Media: Theory, Human Studies, and Instrumentation
Britton Chance; Robert R. Alfano, Editor(s)

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