title: The effects of intense pulsed light (IPL) on blood vessels investigated by mathematical modeling.
abstract: OBJECTIVE
  Intense pulsed light (IPL) sources have been successfully used for coagulation of blood vessels in clinical practice. However, the broadband emission of IPL hampers the clinical evaluation of optimal light parameters. We describe a mathematical model in order to visualize the thermal effects of IPL on skin vessels, which was not available, so far.
  
  
  METHODS
  One IPL spectrum was shifted towards the near infrared range (near IR shifted spectrum: NIRSS) and the other was heavily shifted toward the visible range (visible shifted spectrum: VSS). The broadband emission was separated in distinct wavelengths with the respective relative light intensity. For each wavelength, the light and heat diffusion equations were simultaneously solved with the finite element method. The thermal effects of all wavelengths at the given radiant exposure (15 or 30 J/cm2) were added and the temperature in the vessels of varying diameters (60, 150, 300, 500 microm) was calculated for the entire pulse duration of 30 milliseconds.
  
  
  RESULTS
  VSS and NIRSS both provided homogeneous heating in the entire vessel. With the exception of the small vessels (60 microm), which showed only a moderate temperature increase, all vessels exhibited a temperature raise within the vessel sufficient for coagulation with each IPL parameter. The time interval for effective temperature raise in larger vessels (diameter >60 microm) was clearly shorter than the pulse duration. In most instances, the vessel temperature was higher for VSS when compared to NIRSS.
  
  
  CONCLUSIONS
  We presented a mathematical model capable of calculating the photon distribution and the thermal effects of the broadband IPL emission within cutaneous blood vessels.
authors.affiliation: Department of Dermatology, University of Regensburg, Regensburg, Germany. baeumler.wolfgang@klinik.uni-regensburg.de
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Bäumler
authors.forename: Emre
authors.initials: E
authors.lastname: Vural
authors.forename: Michael
authors.initials: M
authors.lastname: Landthaler
authors.forename: Francesco
authors.initials: F
authors.lastname: Muzzi
authors.forename: Gal
authors.initials: G
authors.lastname: Shafirstein
mesh_terms: D001808:Blood Vessels / Q000528:radiation effects*; D006358:Hot Temperature; D006801:Humans; D007834:Lasers; D028022:Low-Level Light Therapy; D008962:Models, Theoretical; D012867:Skin / Q000098:blood supply*; D012881:Skin Temperature / Q000528:radiation effects