Transient Pressure Field of Ho:YAG Laser Pulse for Lithotripsy - Abstract
For almost 25 years, the lamp-pumped Chromium (Cr3+), Thulium (Tm3+), Holmium (Ho3+) triple-doped yttrium aluminum garnet (CTH:YAG or Ho:YAG) laser has been commercialized for ureteroscopic laser lithotripsy (URSL). However, the transient pressure field profile of the vapor bubbles that arise from laser pulses has not been reported. The transient pressure field of different laser pulses provides further insight into understanding stone ablation and retropulsion. The objective of this study is to measure the transient pressure field profile of the vapor bubbles of standard and custom laser modes of a prototype CTH: YAG laser. The transient pressure field is measured by a hydrophone, and the measurements are taken at various locations from the laser fiber tip. The transient pressure field profiles were successfully measured and constructed with mechanical hydrophones. The maximum transient pressure reached 5.4 MPa for the reference laser and 2.9 MPa for the prototype laser. The transient pressure of the prototype laser’s Standard mode has the highest value, followed by the Fragmenting mode and then the Dusting mode. The study demonstrated that the optical hydrophone is not adequate for measuring laser-induced transient pressure in water because of its lower sensitivity and distorted signal caused by the laser-generated vapor bubble. The transient pressure field profiles were successfully measured and constructed with mechanical hydrophones. The maximum transient pressure reached 5.4 MPa for the reference laser and 2.9 MPa for the prototype laser (Disclaimers: Bench Test results may not necessarily be indicative of clinical performance. The testing was performed by or on behalf of BSC. Data on file. Concept evice or technology. Not available for sale)