Skin burns after laser exposure: Histological analysis and predictive simulation

Thermal effects of laser irradiation on skin are investigated in this paper. The main purpose is to determine the damage level induced by a laser exposure. Potential burns induced by two lasers (wavelength 808 nm and 1940 nm) are studied and animal experimentations are performed. Several exposure durations and laser powers are tested. Based on previous works, a mathematical model dedicated to temperature prediction is proposed and finite-element method is implemented. This numerical predictive tool based on the bioheat equation takes into account heat losses due to the convection on skin surface, blood circulatory and also evaporation. Thermal behavior of each skin layer is also described considering distinct thermal and optical properties. Since the mathematical model is able to estimate damage levels, histological analyses were also carried through. It is confirmed that the mathematical model is an efficient predictive tool for estimation of damage caused by lasers and that thermal effects sharply depend on laser wavelength

Evaluation du risque de brûlure par exposition à des rayonnements lasers. Expérimentations et modélisation.

La technologie laser étant de plus en plus utilisée, l\u27objectif de cette étude est de déterminer quel type d\u27agression laser entraîne quel dégât (brûlure) sur la peau. Il existe en effet unedifférence de diagnostic et de pronostic des lésions en fonction de la longueur d’onde du laser utilisé. Pour ce faire, des expérimentations in vivo sur modèle animal ont été menées à l\u27aide de trois lasers émettant respectivement à 808 nm, 1,94 μm et 10,6 μm. Parallèlement, un modèle mathématique permettant de simuler l\u27effet thermique d\u27une agression laser sur la peau a été développé

Impact of a Lossy Image Compression on Parameter Estimation with Periodic Active Thermal Imaging.

Periodic thermal imaging is a method of active thermography based on a periodic thermal stimulation of an inspected sample material and the analysis of its thermal response when a steady regime is reached. The original data, a sequence of images sampling the thermal response on a large number of periods, are usually stored in a raw format. For accurate exploitation of these measurements, the whole sequence of images requiresa significant amount of storage space. In this report, we address the question of the lossy compression of these sequences of images when they are applied to perform physical parameter estimation. The study investigates the impact of lossy image compression on the performance of the physical parameter estimation procedure, and shows the possibility of preserving robust estimation with high compression rate. Perspectives and applications are then discussed. Performing good enough estimate of physical parameters with compressed images would permit the use of portable thermal cameras with limited resources in terms of data storage. This would enable the use of periodic active thermal imaging to perform relatively low cost embedded characterization of thermal properties of materials

Development of a skin burn predictive model adapted to laser irradiation

Laser technology is increasingly used, and it is crucial for both safety and medical reasons that the impact of laser irradiation on human skin can be accurately predicted. This study is mainly focused on laser–skin interactions and potential lesions (burns). A mathematical model dedicated to heat transfers in skin exposed to infrared laser radiations has been developed. The model is validated by studying heat transfers in human skin and simultaneously performing experimentations an animal model (pig). For all experimental tests, pig’s skin surface temperature is recorded. Three laser wavelengths have been tested: 808 nm, 1940 nm and 10 600 nm. The first is a diode laser producing radiation absorbed deep within the skin. The second wavelength has a more superficial effect. For the third wavelength, skin is an opaque material. The validity of the developed models is verified by comparison with experimental results (in vivo tests) and the results of previous studies reported in the literature. The comparison shows that the models accurately predict the burn degree caused by laser radiation over a wide range of conditions. The results show that the important parameter for burn prediction is the extinction coefficient. For the 1940 nm wavelength especially, significant differences between modeling results and literature have been observed, mainly due to this coefficient’s value. This new model can be used as a predictive tool in order to estimate the amount of injury induced by several types (couple power-time) of laser aggressions on the arm, the face and on the palm of the hand

Skin burns after laser exposure: Histological analysis and predictive simulation

http://www.journals.elsevier.com/burnsInternational audienc