title: Urinary calculus fragmentation during Ho: YAG and Er:YAG lithotripsy.
abstract: OBJECTIVE
  We tested Ho:YAG and Er:YAG laser ablation of human urinary calculi to determine if Er:YAG is a more efficient lithotripsy device.
  
  
  METHODS
  Ablation efficiency of Ho:YAG and Er:YAG lasers was tested at varying energy settings, ranging from the damage threshold to clinical energy setting associated with Ho:YAG laser. Stones of known composition (calcium oxalate monohydrate (COM), cystine, and uric acid (UA)) were irradiated. Crater width, depth, and ablation volumes were determined using an optical coherence tomography (OCT).
  
  
  RESULTS
  For all stones and energy settings, the Er:YAG laser produced deeper craters and larger ablation volumes than Ho:YAG laser. The Ho:YAG laser created wider craters during the multiple pulse process and the shape of craters was irregular.
  
  
  CONCLUSIONS
  The Er:YAG laser is more efficient than the Ho:YAG laser for lithotripsy. The deeper craters produced by the Er:YAG laser is attributed to the high absorption of energy at its wavelength.
authors.affiliation: Harvard Medical School, Wellman Center for Photomedicine, Massachusetts General Hospital, BHX 630, 50 Blossom Street, Boston, 02114, USA. hlee14@partners.org
authors.forename: Ho
authors.initials: H
authors.lastname: Lee
authors.forename: Hyun Wook
authors.initials: HW
authors.lastname: Kang
authors.forename: Joel M H
authors.initials: JM
authors.lastname: Teichman
authors.forename: Junghwan
authors.initials: J
authors.lastname: Oh
authors.forename: Ashley J
authors.initials: AJ
authors.lastname: Welch
mesh_terms: D004871:Erbium; D006695:Holmium; D006801:Humans; D016018:Least-Squares Analysis; D017602:Lithotripsy, Laser / Q000295:instrumentation*; D016896:Treatment Outcome; D014545:Urinary Calculi / Q000628:therapy*
chemical_list: D004871:Erbium; D006695:Holmium