Related Experiment Video
Updated: Jul 16, 2026
10:17
20 mJ, 1 ps Yb:YAG Thin-disk Regenerative Amplifier
Published on: July 12, 2017
Effect of pulse width on object movement in vitro using holmium:YAG laser
Pankaj Kalra1, Ngoc-Bich Le, Demetrius Bagley
1Department of Urology, Thomas Jefferson University, Jefferson Medical College, Philadelphia, Pennsylvania 19107, USA.
Journal of Endourology
|March 7, 2007
Summary
Varying holmium:YAG laser pulse width impacts stone movement during lithotripsy. Longer pulse durations reduce retropulsion, potentially improving stone fragmentation efficiency and reducing fiber repositioning needs.
Area of Science:
- Urology
- Medical Devices
- Laser Technology
Background:
- Holmium:YAG (Ho:YAG) laser lithotripsy is effective for kidney stone removal.
- Optimal Ho:YAG laser lithotripsy requires maintaining fiber tip contact with the calculus.
- Stone retropulsion during Ho:YAG laser lithotripsy necessitates frequent fiber repositioning.
Purpose of the Study:
- To investigate the effect of varying Ho:YAG laser pulse widths on stone retropulsion in vitro.
- To determine if pulse width influences shockwave generation and object migration during lithotripsy.
Main Methods:
- Two experiments were conducted using Ho:YAG laser at 350-microsecond and 700-microsecond pulse widths.
- Experiment 1: Measured displacement of a non-fragmentable ball bearing after single pulse delivery at increasing energies.
- Experiment 2: Determined total energy delivered to a fragmentable phantom before migration using trains of pulses at increasing energies.
Main Results:
- Significantly greater ball bearing movement occurred at the 350-microsecond pulse width for both 200-microm and 400-microm fibers (P < 0.0001 and P < 0.0069, respectively).
- Higher energy settings amplified disparities in object movement.
- The 700-microsecond pulse width allowed for significantly greater total energy delivery before phantom migration (P < 0.0018).
Conclusions:
- Ho:YAG laser lithotripsy generates pressure waves causing some stone retropulsion.
- Laser pulse duration directly influences shockwave generation and subsequent object migration.
- Longer pulse widths (700-microsec) reduce single-shock movement and enhance energy delivery during repetitive shocking, potentially improving clinical efficiency.
