Sampling tissue volumes using frequency-domain photon migration.
We demonstrate the use of Monte Carlo simulations to generate photon scattering density functions (PSDFs) that represent the tissue volume sampled by steady-state and frequency-domain photon migration. We use these results to illustrate how scaling laws can be developed to determine the mean sampling depth of the multiply scattered photons detected by photon migration methods that remain valid outside the bounds of the standard diffusion approximation, i.e., at small source-detector separations and in media where the optical absorption is significant relative to scattering. Using both the PSDF computation and the newly formulated scaling laws, we focus on a comprehensive description of the effects of source modulation frequency, optical absorption, and source-detector separation on the depth of the sampled tissue volume as well as the sensitivity of frequency-domain photon migration measurements to the presence of a localized absorption heterogeneity.
Bevilacqua
Frédéric
F
Laser Microbeam and Medical Program, Beckman Laser Institute, 1002 Health Sciences Road East, Irvine, California 92612, USA. Frederic.Bevilacqua@ircam.fr
You
Joon S
JS
Hayakawa
Carole K
CK
Venugopalan
Vasan
V
D055592:Biophysical Phenomena; D001703:Biophysics; D004058:Diffusion; D015233:Models, Statistical; D009010:Monte Carlo Method; D017785:Photons; D012542:Scattering, Radiation