The application of pulsed photothermal radiometry (PPTR) diagnostics to characterize port wine stain (PWS) lesions is discussed. A PPTR signal of a PWS in response to pulsed laser exposure is shown to consist of an initial "T-jump" due to epidermal melanin absorption and a `delayed thermal wave' resulting from laser generated heat in subsurface blood vessels diffusing to the skin surface. A prototype PPTR instrument incorporating an infrared fiber is constructed which facilitates convenient skin-site accessibility. Laser heating of the infrared collection optics results in an artifactual signal which overestimates the initial "T-jump." Magnitude of the error is measured and a method to eliminate it is suggested.
T. E. Milner, J. S. Nelson, N. Tran, A. Katzir, L. O. Svaasand, S. L. Jacques, "Clinical use of pulsed photothermal radiometry," SPIE Proceedings of Lasers in Otolaryngology, Dermatology, and Tissue Welding, edited by S. M. Shapshay, R. R. Anderson, J. V. White, R. A. White, L. S. Bass, 1876, 122- 128 (1993).