Visual Simulation of Ultraviolet Dose on Human Skin with Sunscreen Applied Using Minimal Erythema Dose

Abstract

This study presents a method for deriving the effectiveness function of sunscreen's sun protection factor (SPF) over time. Based on the SPF effectiveness function, a simulation-based framework was developed for visualizing the ultraviolet B (UVB) dose absorbed by the skin under various environmental and personal factors. The simulation-based framework is divided into three steps: deriving the SPF effectiveness function of sunscreen, calculating the UVB dose absorbed by the skin, and visualizing. In the step of SPF effectiveness function derivation, an in-vivo test was conducted to evaluate the persistency functions of sunscreens. Data from previous studies were used to evaluate the insufficiency function, which is the relationship between residuals and their corresponding SPF values. For various sunscreen products, SPF effectiveness functions were derived by combining the persistency and insufficiency functions. In the UVB dose calculation phase, the amount of UV irradiation reaching each mesh was calculated by tracking the changes in the sun's trajectory and the motion of human models. The total UVB dose accumulated by each mesh over a period of time was calculated by summing the UVB dose for each time step and combining it with the time-dependent effectiveness of sunscreen. Finally, in the visualization step, each vertex was mapped in two ways: MED-based colors for a more realistic simulation and pseudo-colors used to show slight variations in skin color. Based on the proposed framework, a system was developed to simulate UVB doses in real-time under various conditions. Using this simulation system, each individual can accurately predict the UVB dose absorbed by the skin based on environmental factors, outdoor activities, SPF, and type of sunscreen, to avoid erythema caused by excessive exposure to the sun.