Photons, Physics, and Phantoms—Oh My! Modeling Light Diffusion in Tissue with Monte Carlo Simulations*

Monte Carlo simulations generate highly accurate computer models of photon diffusion in tissue. These simulations can create complex models, including heterogeneous tissues with diverse optical properties and non-linear geometries. Other simulation models, such as those relying on diffusion theory, often break down when close to the light source and sharp boundary edges. The accuracy of the Monte Carlo model was confirmed by comparing fluence distributions of physical phantom models. By layering phantom media with known absorption and scattering coefficients, anatomical models of organs can be physically simulated. These phantom models show high accuracy in fluence distribution between predicted Model Carlo models and simulated tissue. In conjunction with phantom measurements, Monte Carlo modeling will be used to simulate and guide light-activated therapies in cancer models in mice.