Computational modeling and damage threshold prediction of continuous-wave and multiple-pulse porcine skin laser exposures at 1070\u2009nm

Abstract

Computational models are capable of simulating the expected thermal response of biological tissue to laser irradiation. A typical laser tissue model accounts for optical energy deposition, heat transfer, and damage assessment, with the latter often represented by calculation of the Arrhenius integral. Previous studies have successfully employed these methods to predict skin damage thresholds at laser wavelengths with high absorption in water, and usually for single continuous-wave exposures. However, there remains a need for a robust and accurate predictive model in low-absorption, high-scattering cases, such as for exposures in the near-infrared region near 1000\u2009nm. This study presents a framework for modeling laser irradiation of skin tissue at 1070\u2009nm for both continuous-wave and pulsed exposures with durations ranging from 10−2 to 101\u2009s. The authors derive an optical absorption coefficient for the epidermis that agrees with expected chromophore distribution and report the modeled skin thermal responses alongside surface thermography data from in vivo porcine exposures as validation of simulation accuracy. Comparisons of modeled damage thresholds calculated by the Arrhenius integral with documented experimentally determined minimum visible lesion ED50 data exhibit a high degree of agreement. The authors also provide new Arrhenius rate process coefficients of A\u2009=\u20092.74\u2009×\u20091094\u2009s−1 and Ea\u2009=\u20095.90\u2009×\u2009105\u2009J/mol, determined from experimental thermal profiles with a unique method, that demonstrate more accurate threshold predictions than those used in previous modeling studies. The techniques outlined by this study provide a useful tool in assessing potentially hazardous near-infrared laser exposure scenarios.