MP69-03 THE EFFECTS OF LASER PULSE DURATION ON ENERGY DELIVERY AND STONE DAMAGE DURING LASER LITHOTRIPSY (2020)

You have accessJournal of UrologyStone Disease: Surgical Therapy VII (MP69)1 Apr 2020MP69-03 THE EFFECTS OF LASER PULSE DURATION ON ENERGY DELIVERY AND STONE DAMAGE DURING LASER LITHOTRIPSY Derek Ho*, Dominick Scialabba, Russell Terry, Robert Qi, Glenn Preminger, Michael Lipkin, and Pei Zhong Derek Ho*Derek Ho* More articles by this author , Dominick ScialabbaDominick Scialabba More articles by this author , Russell TerryRussell Terry More articles by this author , Robert QiRobert Qi More articles by this author , Glenn PremingerGlenn Preminger More articles by this author , Michael LipkinMichael Lipkin More articles by this author , and Pei ZhongPei Zhong More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000949.03AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Although modern laser lithotripsy (LL) systems offer pulse duration (PD) modulation during treatment, its effect on both the underlying mechanisms of stone damage and treatment efficiency are unclear. We investigate the effects of varying laser PD on the energy delivery to the stone and surrounding fluid and its resultant effects on bubble geometry and stone crater formation. METHODS: Three pulse modes of varying PD (Fragmenting ≈ 75 µs, Standard ≈ 150 µs, Advanced ≈ 200 µs) from a clinical LL system (H Solvo 35-watt laser, Dornier MedTech) were used to treat fixed Begostone samples. A 400 µm laser fiber was placed in contact with the stone surface and delivered varying number of pulses (1 – 100) for each pulse mode (n = 5). Crater volume (CV) was quantified using optical coherence tomography (OQ Labscope, Lumedica) following LL. The effects of PD on cavitation during treatment and power delivery to the stone were quantified with high-speed imaging and photodetector measurements, respectively. RESULTS: We observed a rapid increase in CV over the first 5-10 pulses in all three pulse modes before a plateau after 20-30 pulses, accompanied by a characteristic transition in bubble geometry from a small, flat bubble to a large hemispherical bubble. Longer PDs resulted in higher energy delivery efficiency, but lower mean CV (0.737 mm3, 0.602 mm3, and 0.535 mm3 for fragmentation, standard, and advanced mode after 100 pulses, respectively; p < 0.05). High-speed imaging synced with photodetector measurements correlated higher energy delivery with the expansion of the vapor bubble. CONCLUSIONS: As CV enlarged, more laser energy was absorbed by the intermediate fluid, leading to a large bubble formation with a concomitant reduction in stone damage at increasing pulse numbers. This important observation demonstrates that fiber-stone distance is a critical parameter in treatment efficiency regardless of PD. Significantly, this is the first experimental validation of improved energy delivery to the stone with longer PDs with more pulse energy delivered following the formation of a vapor bubble. However, the reduced CV for longer PD suggests that other factors, such as cavitation erosion and stress, may play a significant role in stone damage. Source of Funding: This projected is supported by the NIH (P20 DK123970). DH is supported by the NIH (K12 DK100024). © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e1044-e1044 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Derek Ho* More articles by this author Dominick Scialabba More articles by this author Russell Terry More articles by this author Robert Qi More articles by this author Glenn Preminger More articles by this author Michael Lipkin More articles by this author Pei Zhong More articles by this author Expand All Advertisement PDF downloadLoading ...