Investigation of Effect of Low-Level Light Therapy by Continuous Wave and Pulse Wave Through Dry Skull by Using Mathematical Modeling

Both Continuous Wave (CW) and Pulse Wave (PW) are used in Low-level Light Therapy (LLLT) treatment
of skin diseases, wound healing, and hair transplantation. At present, LLLT is being used in Alzheimer’s disease treatment. It was found that LLLT can prevent nerve cell death in an in-vitro test. However, LLLT for Alzheimer’s disease requires high energy of light so that the light can pass through the skull and be sufficient to treat Alzheimer’s disease. This study focuses on designing uniform light illumination on the skull, both CW and PW, at a wavelength of 810 nm using the local search algorithm without harming the skin to make the light pass through the skull.Moreover, this study measured the energy density of light when the light through the skull from the simulation. The results found that PW irradiation was able to produce more energy density than CW irradiation, and the energy density that passes the skull is enough to treat Alzheimer’s disease without harming the skin. Also, the PW treatment duration was shorter than CW, where the coefficient of variation of energy density on the skull surface of PWand CWwere 0.037 and 0.036, respectively.