[Introduction to tissue optics and optical dosimetry].
The spatial distribution of radiation during medical laser application is determined by the characteristics of the beam (power, time, beam geometry) and the optical properties of the tissue. The irradiance E (in W/m2) describes the primary laser beam. Scattered radiation, in turn, is taken into account by the fluence rate phi (also in W/m2). The basic parameters of tissue optics are the absorption coefficient mu a, the scattering coefficient mu s and the anisotropy factor g. In addition, derived parameters are also used, i.e., total attenuation coefficient mu t, reduced scattering coefficient mu s', effective attenuation coefficient mu eff, mean free path of a photon d and penetration depth delta. Further tissue properties are the diffuse reflectance Rd and the back-scattering factor k. In an one-dimensional model the fluence rate phi in tissue is a nearly exponential function characterized by the penetration depth delta. At the tissue surface, the relationship exists phi = kE. This model is compared with the results of a computer program based on the finite element method.
Eichler
J
J
Labor für Laseranwendungen, Technische Fachhochschule Berlin.
Kim
B M
BM
D004307:Dose-Response Relationship, Radiation; D006801:Humans; D053685:Laser Therapy; D055095:Optics and Photonics; D012542:Scattering, Radiation