Effect of pulse duration on bubble formation and laser-induced pressure waves during holmium laser ablation

E. Duco Jansen, Thomas Asshauer, Martin Frenz, Massoud Motamedi, Guy Delacrétaz, Ashley J. Welch

Research output: Contribution to journalArticle

106 Citations (Scopus)

Abstract

Background and Objective: One concern during laser ablation of tissue is the mechanical injury that may he induced in tissue in the vicinity of the ablation site. This injury is primarily due to rapid bubble expansion and collapse or due to laser-induced pressure waves. In this study, the effect of laser pulse duration on the thermodynamics of bubble formation and accompanying acoustic pressure wave generation has been investigated. Study Design/Materials and Methods: Q-switched holmium:YAG laser pulses (pulse duration 500 ns, pulse energy 14 mJ) and free-running holmium:YAG laser pulses (pulse duration 100-1,100 μs, pulse energy 200 mJ) were delivered in water and tissue phantoms via a 200- and 400-μm fiber, respectively. The tissue phantoms consisted of polyacrylamide gels with varying mechanical strengths. Bubble formation was recorded with a fast flash photography setup, while acoustic transients were measured with a needle hydrophone. Results: It was observed that, as the pulse length was increased the bubble shape changed from almost spherical for Q-switched pulses to a more elongated cylinder shape for longer pulse durations. The bubble expansion velocity was larger for shorter pulse durations. Only the Q-switched pulse induced a measurable thermo-elastic expansion wave. All pulses that induced bubble formation generated pressure waves upon collapse of the bubble in gels as well as in water. However, the magnitude of the pressure wave depended strongly on the size and geometry of the induced bubble. Conclusion: The magnitude of the collapse pressure wave decreased as laser pulse duration increased. Hence it may be possible to reduce collateral mechanical tissue damage by stretching the holmium laser pulse.

Original languageEnglish (US)
Pages (from-to)278-293
Number of pages16
JournalLasers in Surgery and Medicine
Volume18
Issue number3
DOIs
StatePublished - 1996
Externally publishedYes

Fingerprint

Solid-State Lasers
Laser Therapy
Lasers
Pressure
Water
Photography
Wounds and Injuries
Thermodynamics
Acoustics
Needles
Gels

Keywords

  • acoustics
  • bubble
  • cavitation
  • infrared laser
  • pulse length
  • tissue phantoms

ASJC Scopus subject areas

  • Surgery

Cite this

Effect of pulse duration on bubble formation and laser-induced pressure waves during holmium laser ablation. / Jansen, E. Duco; Asshauer, Thomas; Frenz, Martin; Motamedi, Massoud; Delacrétaz, Guy; Welch, Ashley J.

In: Lasers in Surgery and Medicine, Vol. 18, No. 3, 1996, p. 278-293.

Research output: Contribution to journalArticle

Jansen, E. Duco ; Asshauer, Thomas ; Frenz, Martin ; Motamedi, Massoud ; Delacrétaz, Guy ; Welch, Ashley J. / Effect of pulse duration on bubble formation and laser-induced pressure waves during holmium laser ablation. In: Lasers in Surgery and Medicine. 1996 ; Vol. 18, No. 3. pp. 278-293.
@article{074e908b16e140d0b4e6c7c526cf45d9,
title = "Effect of pulse duration on bubble formation and laser-induced pressure waves during holmium laser ablation",
abstract = "Background and Objective: One concern during laser ablation of tissue is the mechanical injury that may he induced in tissue in the vicinity of the ablation site. This injury is primarily due to rapid bubble expansion and collapse or due to laser-induced pressure waves. In this study, the effect of laser pulse duration on the thermodynamics of bubble formation and accompanying acoustic pressure wave generation has been investigated. Study Design/Materials and Methods: Q-switched holmium:YAG laser pulses (pulse duration 500 ns, pulse energy 14 mJ) and free-running holmium:YAG laser pulses (pulse duration 100-1,100 μs, pulse energy 200 mJ) were delivered in water and tissue phantoms via a 200- and 400-μm fiber, respectively. The tissue phantoms consisted of polyacrylamide gels with varying mechanical strengths. Bubble formation was recorded with a fast flash photography setup, while acoustic transients were measured with a needle hydrophone. Results: It was observed that, as the pulse length was increased the bubble shape changed from almost spherical for Q-switched pulses to a more elongated cylinder shape for longer pulse durations. The bubble expansion velocity was larger for shorter pulse durations. Only the Q-switched pulse induced a measurable thermo-elastic expansion wave. All pulses that induced bubble formation generated pressure waves upon collapse of the bubble in gels as well as in water. However, the magnitude of the pressure wave depended strongly on the size and geometry of the induced bubble. Conclusion: The magnitude of the collapse pressure wave decreased as laser pulse duration increased. Hence it may be possible to reduce collateral mechanical tissue damage by stretching the holmium laser pulse.",
keywords = "acoustics, bubble, cavitation, infrared laser, pulse length, tissue phantoms",
author = "Jansen, {E. Duco} and Thomas Asshauer and Martin Frenz and Massoud Motamedi and Guy Delacr{\'e}taz and Welch, {Ashley J.}",
year = "1996",
doi = "10.1002/(SICI)1096-9101(1996)18:3<278::AID-LSM10>3.0.CO;2-2",
language = "English (US)",
volume = "18",
pages = "278--293",
journal = "Lasers in Surgery and Medicine",
issn = "0196-8092",
publisher = "Wiley-Liss Inc.",
number = "3",

}

TY - JOUR

T1 - Effect of pulse duration on bubble formation and laser-induced pressure waves during holmium laser ablation

AU - Jansen, E. Duco

AU - Asshauer, Thomas

AU - Frenz, Martin

AU - Motamedi, Massoud

AU - Delacrétaz, Guy

AU - Welch, Ashley J.

PY - 1996

Y1 - 1996

N2 - Background and Objective: One concern during laser ablation of tissue is the mechanical injury that may he induced in tissue in the vicinity of the ablation site. This injury is primarily due to rapid bubble expansion and collapse or due to laser-induced pressure waves. In this study, the effect of laser pulse duration on the thermodynamics of bubble formation and accompanying acoustic pressure wave generation has been investigated. Study Design/Materials and Methods: Q-switched holmium:YAG laser pulses (pulse duration 500 ns, pulse energy 14 mJ) and free-running holmium:YAG laser pulses (pulse duration 100-1,100 μs, pulse energy 200 mJ) were delivered in water and tissue phantoms via a 200- and 400-μm fiber, respectively. The tissue phantoms consisted of polyacrylamide gels with varying mechanical strengths. Bubble formation was recorded with a fast flash photography setup, while acoustic transients were measured with a needle hydrophone. Results: It was observed that, as the pulse length was increased the bubble shape changed from almost spherical for Q-switched pulses to a more elongated cylinder shape for longer pulse durations. The bubble expansion velocity was larger for shorter pulse durations. Only the Q-switched pulse induced a measurable thermo-elastic expansion wave. All pulses that induced bubble formation generated pressure waves upon collapse of the bubble in gels as well as in water. However, the magnitude of the pressure wave depended strongly on the size and geometry of the induced bubble. Conclusion: The magnitude of the collapse pressure wave decreased as laser pulse duration increased. Hence it may be possible to reduce collateral mechanical tissue damage by stretching the holmium laser pulse.

AB - Background and Objective: One concern during laser ablation of tissue is the mechanical injury that may he induced in tissue in the vicinity of the ablation site. This injury is primarily due to rapid bubble expansion and collapse or due to laser-induced pressure waves. In this study, the effect of laser pulse duration on the thermodynamics of bubble formation and accompanying acoustic pressure wave generation has been investigated. Study Design/Materials and Methods: Q-switched holmium:YAG laser pulses (pulse duration 500 ns, pulse energy 14 mJ) and free-running holmium:YAG laser pulses (pulse duration 100-1,100 μs, pulse energy 200 mJ) were delivered in water and tissue phantoms via a 200- and 400-μm fiber, respectively. The tissue phantoms consisted of polyacrylamide gels with varying mechanical strengths. Bubble formation was recorded with a fast flash photography setup, while acoustic transients were measured with a needle hydrophone. Results: It was observed that, as the pulse length was increased the bubble shape changed from almost spherical for Q-switched pulses to a more elongated cylinder shape for longer pulse durations. The bubble expansion velocity was larger for shorter pulse durations. Only the Q-switched pulse induced a measurable thermo-elastic expansion wave. All pulses that induced bubble formation generated pressure waves upon collapse of the bubble in gels as well as in water. However, the magnitude of the pressure wave depended strongly on the size and geometry of the induced bubble. Conclusion: The magnitude of the collapse pressure wave decreased as laser pulse duration increased. Hence it may be possible to reduce collateral mechanical tissue damage by stretching the holmium laser pulse.

KW - acoustics

KW - bubble

KW - cavitation

KW - infrared laser

KW - pulse length

KW - tissue phantoms

UR - http://www.scopus.com/inward/record.url?scp=0029977969&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0029977969&partnerID=8YFLogxK

U2 - 10.1002/(SICI)1096-9101(1996)18:3<278::AID-LSM10>3.0.CO;2-2

DO - 10.1002/(SICI)1096-9101(1996)18:3<278::AID-LSM10>3.0.CO;2-2

M3 - Article

VL - 18

SP - 278

EP - 293

JO - Lasers in Surgery and Medicine

JF - Lasers in Surgery and Medicine

SN - 0196-8092

IS - 3

ER -