Holmium:YAG laser lithotripsy: A dominant photothermal ablative mechanism with chemical decomposition of urinary calculi
✍ Scribed by Chan, Kin Foong; Vassar, George J.; Pfefer, T. Joshua; Teichman, Joel M.H.; Glickman, Randolph D.; Weintraub, Susan T.; Welch, Ashley J.
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 718 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0196-8092
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✦ Synopsis
Background and Objective:
Evidence is presented that the fragmentation process of long-pulse Holmium:YAG (Ho:YAG) lithotripsy is governed by photothermal decomposition of the calculi rather than photomechanical or photoacoustical mechanisms as is widely thought. The clinical Ho:YAG laser lithotriptor (2.12 m, 250 s) operates in the free-running mode, producing pulse durations much longer than the time required for a sound wave to propagate beyond the optical penetration depth of this wavelength in water. Hence, it is unlikely that shock waves are produced during bubble formation. In addition, the vapor bubble induced by this laser is not spherical. Thus the magnitude of the pressure wave produced at cavitation collapse does not contribute significantly to lithotripsy. Study Design/Materials and Methods: A fast-flash photography setup was used to capture the dynamics of urinary calculus fragmentation at various delay times following the onset of the Ho:YAG laser pulse. These images were concurrently correlated with pressure measurements obtained with a piezoelectric polyvinylidene-fluoride needle-hydrophone. Stone mass-loss