title: Laser-tissue interaction with a continuous wave 3-mcm fibre laser: preliminary studies with soft tissue.
abstract: OBJECTIVE
  Lasers operating at wavelengths in the mid-infrared region have become increasingly popular for applications in areas of surgery and medicine. Advances in fibre laser technology have introduced a highly efficient, compact, diode-pumped source operating at around the 3-mcm wavelength. This study examines the effects of this recently developed laser on soft biological tissue.
  
  
  METHODS
  Chicken breast and liver tissue samples were exposed to 800 mW continuous wave laser power, at a wavelength of 2.71 mcm, with incident spot sizes of around 150 mcm. Samples were inspected grossly immediately after laser irradiation and also prepared for histologic processing.
  
  
  RESULTS
  After irradiation, visual assessment of changes at sample surfaces indicated a region of thermally affected tissue surrounding the ablation crater. This region was observed to grow in size to around 1.0 mm in diameter after 3 seconds of laser exposure at 800 mW. An ablation velocity of 0.80 mm.s(-1) was determined in chicken breast for the same incident laser parameters. Analysis of samples irradiated at 800 mW and processed for histology revealed minimal damage at hole boundaries and no signs of char formation, providing incident exposure times were restricted to below around 0. 5 seconds.
  
  
  CONCLUSIONS
  This fibre laser source has demonstrated its potential to fulfil medical applications, enabling accurate, precise tissue removal to proceed at a rapid ablation rate. The efficiency and small size of the laser are attractive features.
authors.affiliation: Laser Photonics Research Group, Department of Physics and Astronomy, University of Manchester, Manchester, United Kingdom. mp@fs4.ph.man.uk
authors.forename: M C
authors.initials: MC
authors.lastname: Pierce
authors.forename: S D
authors.initials: SD
authors.lastname: Jackson
authors.forename: M R
authors.initials: MR
authors.lastname: Dickinson
authors.forename: T A
authors.initials: TA
authors.lastname: King
authors.forename: P
authors.initials: P
authors.lastname: Sloan
mesh_terms: D000818:Animals; D001940:Breast / Q000528:radiation effects; D002645:Chickens; D004871:Erbium; D066298:In Vitro Techniques; D053685:Laser Therapy / Q000379:methods*; D007834:Lasers / Q000009:adverse effects*; D008099:Liver / Q000528:radiation effects; D018482:Muscle, Skeletal / Q000528:radiation effects; D017695:Soft Tissue Injuries / Q000209:etiology*
chemical_list: D004871:Erbium