title: Optical properties of native and coagulated porcine liver tissue between 400 and 2400 nm.
abstract: OBJECTIVE
  Laser induced thermotherapy (LITT) is a promising treatment for irresectable liver tumors. For predicting the effects of laser applications and optimizing irradiation planning in LITT, knowledge about light distribution in tissue, optical tissue properties (absorption, scattering, anisotropy, penetration depth) and their changes due to thermal denaturation is indispensable.
  
  
  METHODS
  The optical parameters in healthy porcine liver were determined in the native state and after thermal coagulation using a double integrating sphere system in the wavelength range of 400-2400 nm.
  
  
  RESULTS
  Optical parameters showed significant fluctuations in the examined wavelength range mainly due to the water and hemoglobin content in the tissue. The greatest optical penetration depth of 7.46 mm was achieved at 1070 nm. After thermal coagulation, a clear increase in scattering and a slight decrease in absorption was found, which results in a decreased optical penetration depth.
  
  
  CONCLUSIONS
  In order to ensure a safe and effective procedure, an adjustment of the laser power to the decreasing penetration depth is recommended during therapy. These results provide a better understanding of laser-tissue interaction and may be helpful to investigators in the field of light dosimetry in liver tissue.
authors.affiliation: Department of General, Vascular and Thoracic Surgery, University Hospital Benjamin Franklin, Freie Universitaet of Berlin, Berlin, Germany. ritz@ukbf.fu-berlin.de
authors.forename: J P
authors.initials: JP
authors.lastname: Ritz
authors.forename: A
authors.initials: A
authors.lastname: Roggan
authors.forename: C
authors.initials: C
authors.lastname: Isbert
authors.forename: G
authors.initials: G
authors.lastname: Müller
authors.forename: H J
authors.initials: HJ
authors.lastname: Buhr
authors.forename: C T
authors.initials: CT
authors.lastname: Germer
mesh_terms: D000818:Animals; D016880:Anisotropy; D006979:Hyperthermia, Induced; D017075:Laser Coagulation; D008027:Light; D008099:Liver / Q000502:physiology* / Q000528:radiation effects*; D008113:Liver Neoplasms / Q000601:surgery*; D009010:Monte Carlo Method; D055095:Optics and Photonics; D012542:Scattering, Radiation; D013552:Swine