Abstract

Thermography is a widespread non-contact imaging method for determining temperature. Its application in medicine, however, has so far been limited and its significance h as n ot b een e xtensively r eviewed i n t his field. Hence the applicability of thermography in laser medicine has been evaluated by determining the corresponding essential parameters. This includes the emissivity of biological tissue, tissue phantoms and cylindrical light diffusers used for interstitial photodynamic therapy (iPDT).

The time-dependent surface temperature of light diffusers for iPDT was thermographically recorded in air and compared to thermocouple measurements. Furthermore, laser light was applied via surface-parallel cylindrical light diffusers for iPDT to a tissue phantom and to porcine brain tissue in an iPDT-like setup. In case of the tissue phantom, four light diffusers were positioned at different lateral positions and depths below the surface, in case of the porcine tissue, only one diffuser was used. The temperature distribution at the surface was recorded thermographically and by a thermocouple. The results were compared to Monte Carlo based simulations of the temperature distribution at the surface.

In the context of laser medicine, thermography seems useful for the inspection of components for laser light application. To protect tissue from unwanted thermal effects, the surface temperature of light applicators can be examined to localize potential temperature hot spots. Nevertheless limitations of thermography have to be considered, especially the fact that this method provides information exclusively about the temperature distribution at the surface.

© 2019 SPIE/OSA