A predictive model of the requisite minimal erythema dose between 308-nm monochromatic excimer light and 311-nm narrowband Ultraviolet-B light.

Abstract

There are limited data in the relationship between the minimal erythema dose (MED) of 308-nm monochromatic excimer light (MEL) and 311-nm Narrowband UVB (NB-UVB). To establish a predictive model of the relationship between MEDs of both wavelengths. An MED test was performed on the back of 40 healthy Thai volunteers. One side was irradiated with 308-nm MEL, and the opposite side was irradiated with 311-nm NB-UVB. The correlation and a predictive model of the relationships were then analyzed. There was a positive correlation in the MED of both wavelengths (r=0.82, p < 0.001). A predicted MED of 308-nm MEL was based on Y=62.421 + 0.439X, where Y and X were a predicted MED of 308-nm MEL and an actual 311-nm NB-UVB, respectively. This model could predict an MED of 308-nm MEL by using an actual MED of 311-nm NB-UVB with a root mean square difference of 13.64%, and a mean bias difference of 0.63%. All volunteers were Fitzpatrick's skin phototype type IV. The predictive model might not generalize to other skin phototypes. We established a predictive model of the relationship between MED of 308-nm MEL and 311-nm NB-UVB with acceptable accuracy.