Infrared measurement of human skin temperature to predict the individual maximum safe radiant exposure (IMSRE).

Background and Objectives Radiant exposure (RE) is a critical treatment parameter to be optimized for laser hair removal (LHR). An objective and quantitative method to assess the individual maximum safe radiant exposure (IMSRE) would help clinicians optimize LHR while at the same time providing the safest possible laser therapy. Study Design Pulsed photo-thermal radiometry (PPTR) measurements were on a total of 403 spots on 13 volunteers. The radiometric signal at 20 milliseconds after the diagnostic laser pulse was used to predict the IMSRE using a simple analytic relationship. Laser pulses (wavelength 755 nm, 3 milliseconds pulse, 50 milliseconds cryogen spray cooling, 30 milliseconds delay) with RE's below and above the predicted IMSRE (range: 10–100 J/cm2) were applied and resulting injuries quantified through blind scoring. Results IMSRE can be predicted quite robustly with PPTR for the broad range of human skin photo-types (I–IV) considered in this study. Conclusions The method presented herein should be useful in helping clinicians optimize LHR on an individual patient basis, with the highest possible safety. Lasers Surg. Med. 39:757–766, 2007. © 2007 Wiley-Liss, Inc.