Evaluation of absorbed light dose in human skin tissue during Light Therapy by 630nm LED light

Body temperature and oxygen saturation are two important factors to evaluate the wound healing and infection situation in human. Because of the higher oxygen levels in the blood, the wound infection rate in the body temperature below 36 °C will be 10% higher than that in the body temperature higher than 36 °C. During Light therapy (LT), the body temperature will be enhanced and the higher cell division rate can make the wound healing faster. In the past, the radiation treatment in photodynamic therapy (PDT) is usually processed by red light with a wavelength of 633 ± 2 nm and the light dose is approximately from 20 to 50 J/cm2. However, the skin of different patient has a different radiation absorption, so the change of temperature in human body will also be different. Based on the varied radiation light dose, this study aims to analyze the impact of the change of oxygen saturation (SpO₂) to obtain the proper irradiation process (PIP). In the experiments, the red LED light (630 nm) was adopted to irradiate on the human body and its output power can be varied to observe the body temperature change. The result of the experiment shows that the skin temperature can keep at 37°C using 950 mW power, and SpO₂ (90.8638 %) can also have the maximum increase. In addition, SpO₂ (91.5115 %) won´t increase if the irradiance is over 30 minutes. Therefore, the PIP can keep steadily the skin temperature at normal body temperature (NBT, 37°C) and provide the best reference for dermatologists to improve the therapeutic effect of patient effectively.