The application of pulsed photothermal radiometry (PPTR) diagnostics to characterize port wine stain (PWS) lesions is discussed. Influence of epidermal absorbance and PWS depth on the PPTR signal is analyzed using an in-vitro model of PWS skin consisting of multilayered collagen films. An instrument is constructed and used for patient and animal model PPTR measurements. When an infrared fiber is incorporated, the instrumentation facilitates convenient skin-site accessibility. Modulation of the PPTR signal and homodyne detection substantially improve the system signal-to-noise ratio over previous methods. Given the measured PPTR signal, an algorithm computes the initial temperature distribution in the PWS skin immediately after the laser pulse. The use and limitations of the algorithm are presented and discussed.
T. E. Milner, J. S. Nelson, N. Tran, A. Katzir, L. O. Svaasand, S. L. Jacques, "Pulsed photothermal radiometry of port-wine stains," SPIE Proceedings of Laser-Tissue Interaction IV, edited by S. L. Jacques, A. Katzir, 1882, 34-42 (1993).