A new Monte Carlo program for simulating light transport through Port Wine Stain skin

Abstract

A new Monte Carlo programme is presented for simulating light transport through clinically normal skin and skin that has Port Wine Stains (PWS) vessels. The program consists of an eight layer mathematical skin model constructed from optical coefficients described previously.A simulation including diffuse illumination at the surface and subsequent light transport through the model is carried out using a Radiative Transfer Theory (RTT) ray-tracing technique. Total reflectance values over 39 wavelengths are scored by the addition of simulated light returning to the surface within a specified region and surface reflections (calculated using Fresnel's equations). These reflectance values are compared to measurements from individual participants and characteristics of the model are adjusted until adequate agreement is produced between simulated and measured skin reflectance curves.The absorption and scattering coefficients of the epidermis are adjusted through changes in the simulated concentrations and mean diameters of epidermal melanosomes to reproduce non-lesional skin colour. Pseudo-cylindrical horizontal vessels are added to the skin model and their simulated mean depths, diameters and number densities are adjusted to reproduce measured PWS skin colour.Accurate reproductions of colour measurement data are produced by the program, resulting in realistic predictions of melanin and PWS blood vessel parameters. Using a modest personal computer, the simulation currently requires an average of five and a half days to complete.

Photothermal treatment of port-wine stains using erythrocyte-derived particles doped with indocyanine green: a theoretical study

“…10(e) and 10(f)]. These results suggest that similar to the optical response of single blood vessel, there may be shadowing effects to reduce the energy deposited to deeper blood vessels 49 . Such effects can occur if vessels are as close as a few microns 50 .…”

Monte Carlo modelling of photodynamic therapy treatments comparing clustered three dimensional tumour structures with homogeneous tissue structures

“…To our knowledge the majority of existing MCRT models simulating PDT assume uniform distributions of skin tissue (Zhu and Liu, 2013). Some models introduce layers of different tissue types and/or tumours represented by geometric shapes (Campbell et al, 2015a;Binzoni et al, 2008;Lister et al, 2014Lister et al, , 2012bJacques, 2010;Wang et al, 1995;Meglinski and Matcher, 2003). Three dimensional (3D) MCRT models have however previously been introduced when studying brain tissue (Boas et al, 2002) and blood vessel networks (Davis et al, 2011).…”