title: Water content contribution in calculus phantom ablation during Q-switched Tm:YAG laser lithotripsy.
abstract: Q-switched (QS) Tm:YAG laser ablation mechanisms on urinary calculi are still unclear to researchers. Here, dependence of water content in calculus phantom on calculus ablation performance was investigated. White gypsum cement was used as a calculus phantom model. The calculus phantoms were ablated by a total 3-J laser pulse exposure (20 mJ, 100 Hz, 1.5 s) and contact mode with N=15 sample size. Ablation volume was obtained on average 0.079, 0.122, and 0.391  mm3 in dry calculus in air, wet calculus in air, and wet calculus in-water groups, respectively. There were three proposed ablation mechanisms that could explain the effect of water content in calculus phantom on calculus ablation performance, including shock wave due to laser pulse injection and bubble collapse, spallation, and microexplosion. Increased absorption coefficient of wet calculus can cause stronger spallation process compared with that caused by dry calculus; as a result, higher calculus ablation was observed in both wet calculus in air and wet calculus in water. The test result also indicates that the shock waves generated by short laser pulse under the in-water condition have great impact on the ablation volume by Tm:YAG QS laser.
authors.affiliation: Boston Scientific Corporation, 3070 Orchard Drive, San Jose, California 95134, United States.
authors.forename: Jian J
authors.initials: JJ
authors.lastname: Zhang
authors.affiliation: Becton, Dickinson and Company, 2350 Qume Dr, San Jose, California 95131, United States.
authors.forename: Danop
authors.initials: D
authors.lastname: Rajabhandharaks
authors.affiliation: Boston Scientific Corporation, 3070 Orchard Drive, San Jose, California 95134, United States.
authors.forename: Jason Rongwei
authors.initials: JR
authors.lastname: Xuan
authors.affiliation: Illumina, 25861 Industrial Blvd, Hayward, California 94545, United States.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.affiliation: Boston Scientific Corporation, 3070 Orchard Drive, San Jose, California 95134, United States.
authors.forename: Ray W J
authors.initials: RW
authors.lastname: Chia
authors.affiliation: Medical Device Development in San Francisco Bay Area, San Francisco, California, United States.
authors.forename: Tom
authors.initials: T
authors.lastname: Hasenberg
authors.affiliation: Pukyong National University, Department of Biomedical Engineering, Room1210, Builiding A12, 45 Yongso-ro, Nam-gu, Busan 608-737, South Korea.
authors.forename: Hyun Wook
authors.initials: HW
authors.lastname: Kang
mesh_terms: D004867:Equipment Design; D006801:Humans; D053844:Lasers, Solid-State; D008096:Lithotripsy; D017602:Lithotripsy, Laser / Q000379:methods*; D008853:Microscopy; D019047:Phantoms, Imaging; D014545:Urinary Calculi / Q000473:pathology*; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water