MODELING THE DISTRIBUTION OF LASER-LIGHT IN PORT-WINE STAINS WITH THEMONTE-CARLO METHOD

Using the Monte Carlo method, we have calculated the distribution of a bsorbed light in skin during the laser treatment of port-wine stains. Our model includes the effect that the blood capillaries and epidermis have on the propagation of light through skin. It is more complete th an those used by previous workers. In this paper, we change the number of scattering dimensions, the spot diameter, and the capillary separa tion and diameter, and we use the wavelengths 577 nm and 585 nm. One-d imensional scattering calculations are misleading but two-dimensional results suffice for large spot diameters. The model shows that changin g the position or diameter of the capillaries has a larger effect on t he distribution of absorbed light in the skin than changing the wavele ngth of the laser beam from 577 nm to 585 nm. Changing the wavelength does increase absorption in the deeper capillaries, but this is not si gnificant. From our results, we discuss the optimal treatment of port- wine stains.