title: Optimal laser fiber rotational movement during photoselective vaporization of the prostate in a bovine ex-vivo animal model.
abstract: OBJECTIVE
  Photoselective vaporization of the prostate (PVP) has emerged as an effective debulking procedure for prostatic urinary obstruction. Surgical technique for the most efficient vaporization has, however, received little scientific investigation. We used an ex-vivo bovine prostate model to investigate how variation in the angle of laser fiber rotational movement ("sweeping") affects prostate tissue vaporization efficiency.
  
  
  METHODS
  Experiments were conducted using the GreenLight™ HPS 120W laser system. A single surgeon performed a clinical PVP video analysis, forming the basis of our study design. Sixty bovine prostate specimens were vaporized using an ex-vivo chamber equipped with computer-assisted axial movements. Specimens were vaporized at a fixed sweeping speed (0.5 sweeps/sec) and variable sweeping angles (0, 15, 30, 60, 90, and 120 degrees). The volume of tissue vaporized was calculated from cross sections and compared by a two-sample t test.
  
  
  RESULTS
  Clinical PVP video analysis of a single experienced surgeon showed a mean angle of 47.7 degrees with 25% of vaporization between 0 and 30 degrees. Ex-vivo analysis showed larger sweeping angles generated wider but more superficial vaporization defects, leading to smaller vaporized volumes. Specifically, vaporization volumes with angles of 0, 15, or 30 degrees were significantly greater than those with rotational angles of 45, 60, and 90 degrees (1.5-3.0 X; P<0.05). The depth of tissue coagulation significantly increased with greater rotational angles.
  
  
  CONCLUSIONS
  Optimal PVP occurred at narrower angles of laser fiber sweeping in our ex-vivo model. Our findings highlight that PVP laser fiber movement can be tested in a scientific manner, identifying parameters to maximize vaporization efficiency.
authors.affiliation: Department of Urology, Weill-Cornell Medical Center, New York, New York 10065, USA. charlesosterberg@gmail.com
authors.forename: E Charles
authors.initials: EC
authors.lastname: Osterberg
authors.forename: Eric C
authors.initials: EC
authors.lastname: Kauffman
authors.forename: Hyun Wook
authors.initials: HW
authors.lastname: Kang
authors.forename: Ed
authors.initials: E
authors.lastname: Koullick
authors.forename: Benjamin B
authors.initials: BB
authors.lastname: Choi
mesh_terms: D000818:Animals; D002417:Cattle; D053685:Laser Therapy / Q000295:instrumentation / Q000379:methods*; D007834:Lasers; D008297:Male; D023421:Models, Animal; D009068:Movement; D011467:Prostate / Q000601:surgery*; D012399:Rotation; D014741:Video Recording