Photon diffusion equation

Photon diffusion equation is a second order partial differential equation describing the time behavior of photon fluence rate distribution in a low-absorption high-scattering medium.

Its mathematical form is as follows. where is photon fluence rate (W/cm2), is del operator, is absorption coefficient (cm−1), is diffusion constant, is the speed of light in the medium (m/s), and is an isotropic source term (W/cm3).

Its main difference with diffusion equation in physics is that photon diffusion equation has an absorption term in it.

Application

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Medical Imaging

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The properties of photon diffusion as explained by the equation is used in diffuse optical tomography.

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