Evaluation of Diffuse Reflectance in Multi-layered Tissue for High Intensity Laser Therapy

Abstract

Pain is one of the quite common symptoms in clinics and many treatment methods have beenapplied to relieve pain. Among the treatments, high-intensity light therapy for pain has beenintroduced, but this therapy has not been fully supported by confirmed efficacy due to the absenceof quantitative assessments and treatment feedback data in real time. In this study, the evaluationof light distribution in tissue was performed with current high-intensity light sourcesquantitatively using light-tissue interaction simulations. The diffuse reflectance in tissue wasgenerated using Monte Carlo simulation that traces photons as they undergo multiple scattering andabsorption within each tissue layer (skin, fat, and muscle) and within multi-layered tissue. Theresults showed that the highest diffuse reflectance and the deepest penetration of tissue wereachieved at λ=830 nm when compared with other wavelengths likeλ=650 nm, 980 nm and 1064 nm.