Modeling laser treatment of port wine stains with a computer- reconstructed biopsy

T. Joshua Pfefer, Jennifer Kehlet Barton, Derek J. Smithies, Thomas E. Milner, J. Stuart Nelson, Martin J.C. Van Gemert, Ashley J. Welch

Research output: Contribution to journalArticle

56 Scopus citations

Abstract

Background and Objective: The efficacy of laser treatment of port wine stains (PWS) has been shown to be highly dependent on patient-specific vasculature. The effect of tissue structure on optical and thermal mechanisms was investigated for different pulse durations by using a novel theoretical model that incorporates tissue morphology reconstructed tomographically from a PWS biopsy. Study Design/Materials and Methods: An optical-thermal numerical model capable of simulating arbitrarily complex, three-dimensional tissue geometries was developed. The model is comprised of (1) a voxel-based Monte Carlo optical model, (2) a finite difference thermal model, and (3) an Arrhenius rate process calculation to predict the distribution of thermal damage. Simulations based on previous computer-based reconstruction of a series of 6 μm sections from a PWS biopsy were performed for laser pulse durations (τ(p)) of 0.5, 5.0, and 10.0 ms at a wavelength of 585 nm. Results: Energy deposition rate in the blood vessels was primarily a function of vessel depth in skin, although shading effects were evident. Thermal confinement and selectivity of damage were seen to be inversely proportional to pulse duration. The model predicted blood-specific damage for τ(p) = 0.5 ms, vascular and perivascular damage for τ(p) = 5 ms, and widespread damage in superficial regions for τ(p) = 10 ms. The effect of energy deposition in the epidermis was most pronounced for longer pulse durations, resulting in increased temperature and extent of damage. Conclusion: Pulse durations between 0.5 and 5 ms are likely optimal for the PWS analyzed. The incorporation of a tomographically reconstructed PWS biopsy into an optical- thermal model represents a significant advance in numerical modeling of laser-tissue interaction.

Original languageEnglish (US)
Pages (from-to)151-166
Number of pages16
JournalLasers in Surgery and Medicine
Volume24
Issue number2
DOIs
StatePublished - Mar 27 1999

Keywords

  • Finite difference
  • Heat transfer
  • Light propagation
  • Monte Carlo
  • Numerical modeling
  • Pulse duration
  • Thermal damage
  • Tissue reconstruction

ASJC Scopus subject areas

  • Surgery
  • Dermatology

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