Simulation of laser propagation through a three-layer human skin model in the spectral range from 1000 to 1900 nm

Abstract

For understanding the mechanisms of low-level laser/light therapy (LLLT), accurate knowledge of light interaction with tissue is necessary. We present a three-dimensional, multilayer reduced-variance Monte Carlo simulation tool for studying light penetration and absorption in human skin. Local profiles of light penetration and volumetric absorption were calculated for uniform as well as Gaussian profile beams with different spreads over the spectral range from 1000 to 1900 nm. The results showed that lasers within this wavelength range could be used to effectively and safely deliver energy to specific skin layers as well as achieve large penetration depths for treating deep tissues, without causing skin damage. In addition, by changing the beam profile from uniform to Gaussian, the local volumetric dosage could increase as much as three times for otherwise similar lasers. We expect that this tool along with the results presented will aid researchers in selecting wavelength and laser power in LLLT.

Measurement of absorption and reduced scattering coefficients in Asian human epidermis, dermis, and subcutaneous fat tissues in the 400- to 1100-nm wavelength range for optical penetration depth and energy deposition analysis

“…Skin tissue structure is modeled as three layers comprising the epidermis, dermis, and subcutaneous fat. 8,9 The optical properties of skin tissue, especially of the epidermis, dermis, and subcutaneous fat, are key parameters for obtaining adequate light distributions.…”

Biological effects and medical applications of infrared radiation

“…On the macroscopic scale, the Monte Carlo simulation tool has been applied for studying the light penetration and absorption in human skin during LLLT. Nasouri et al simulated laser propagation through a three-layer human skin model in the spectral range from 1000 to 1900 nm [131]. This type of analysis is necessary to design parameters to maximze the depth of light penetration into tissue, without any risk of causing thermal damage to the upper layers of the skin.…”

New Insights into Cutaneous Laser Stimulation – Dependency on Skin and Laser Type

“…Therefore, the optical parameters (absorption coefficient, µa) were adjusted for each type of laser. For the Nd:YAP laser wavelength (1,340 nm), the optical parameters were based on (Salomatina et al, 2006;Frahm et al, 2010;Jacques, 2013;Marchandise et al, 2014;Nasouri et al, 2014). For wavelengths far above 1,100 nm, the optical parameters of the tissue approach those of water (Bromm and Treede, 1983;Friebel et al, 2009), which also includes the CO2 laser wavelength (10,600nm).…”