Wednesday, July 9, 2008

LASER TISSUE INTERACTION

The role of lasers in dermatology has increased dramatically over the past two decades. A fundamental understanding of laser-tissue interactions is vital for the proper and appropriate use in clinical practice.

1. Light can interact with tissue in four key ways:
  • Transmission
  • Reflection
  • Scattering
  • Absorption

2. Selective photothermolysis

  • The theory of selective photothermolysis refers to laser energy absorption by a target chromophore without significant thermal damage to surrounding tissue.
  • To achieve selective photothermolysis, 3 main factors:
  • A. The laser must produce a beam of light with a wavelength preferentially absorbed by the chromophore in the lesion.
  • B. The pulse duration of the laser beam must be shorter than the thermal relaxation time of the chromophore to prevent the spread of thermal energy beyond the targeted chromophore.
  • C. The energy delivered to the site (fluence) must be high enough to destroy the chromophore within the pulse duration.

No comments: