Pulsed photothermal radiometry as a method for investigating blood vessel-like structures.

Pulsed photothermal radiometry (PPTR) is known to be suit- able for in vivo investigations of tissue optical properties. As a non- contact, nondestructive method it is a very attractive candidate for on-line dosimetry of laser treatments that rely on thermal laser-tissue interaction. In this article, we extend the one-dimensional (1D) ana- lytical formalism that has widely been used to describe PPTR signals to a two-dimensional treatment of a simplified model of a blood ves- sel. This approach leads to quantitative description of a PPTR signal that, unlike in an 1D treatment, not only shows changes in time, but also varies in space. Using this approach, we are able to gain instruc- tive understanding on how target characteristics of a blood vessel-like structure influence such a spatiotemporal PPTR signal. Likewise, the ability of extracting target features from those measurements is evalu- ated. Subsequently, we present experimental realization of the ideal- ized model of a blood vessel as used in our theory. Comparison of actual PPTR measurements with theoretical predictions allow vessel localization laterally and in depth. Using our setup, we furthermore demonstrate the influence of flow inside the vessel on the measured signal. © 2001 Society of Photo-Optical Instrumentation Engineers.