Model Predictions and Measured Skin Damage Thresholds for 1.54 μm Laser Pulses in Porcine Skin

摘要

A new source-term thermal model was used to determine the skin temperature rise using porcine skin parameters for various wavelengths, pulse durations, and laser spot sizes and is compared to the Takata thermal model. Expanding on this preliminary source-term model using a Gaussian profile to describe the spatial extent of laser pulse interaction in skin, we report on the coupling of temporal consideration to the model. Computer simulation of the new source-term model and the Takata thermal model are presented to highlight the theoretical extent of thermal damage. Laser exposures of 1.54 μm, 0.60 ms in duration and using spot sizes of 0.7 mm and 1.0 mm were applied to the porcine skin. The damage thresholds were determined at 1 hour and 24 hours post-exposures using probit analysis. The ED_(50) for these skin exposures at 24 hours post-exposure were 20 J/cm~2 and 8.1 J/cm~2 respectively. These damage thresholds are compared with our model predictions and another thermal model with the damage integral predicting damage levels. They are also compared with previously published skin thresholds and with the ANSI Standard's MPE for 1540 nm lasers at 0.60 ms.