Characterization of handpieces to control tissue ablation with pulsed CO2 laser

Rudolf M. Verdaasdonk, Christiaan F.P. Van Swol, Judith Coates

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

2 Citations (Scopus)
15 Downloads (Pure)


Focusing handpieces used for CO2 beam delivery allow large variation of the power density in the spot depending on the distance to the tissue and hence the effect on the tissue. In contrast to the cw CO2 laser, the pulsed CO2 laser vaporizes tissue water instantly (:=ablation threshold), leaving a charless crater in the tissue surface. Only if the fluence is below or near threshold, the tissue effects are comparable with the cw laser. The threshold and tissue effects were studied for focusing (f119 mm) and collimating (0 3 mm) handpieces coupled to an ultrapulsed CO2 laser. Using a special thermal imaging setup based on Schuieren techniques, the ablation threshold was determined depending on spotsize and pulse energy (1-200 mJ). In the focus of the handpiece, the threshold was already exceeded at 1 mJ, creating holes that were larger than the theoretical expected spotsize. The ablation threshold (J/cm2) increased for larger spotsizes. Below threshold, there is heating of the tissue resulting in coagulation. Above threshold, the exploding water vapor consumed thermal energy suppressing heating of the surrounding tissue. The gaussian shape of the collimated beam results in relatively more thermal effects. Focusing handpieces provide a wide range in power density and thus require experience from the surgeon. Collimated handpieces might be more easy to handle but offer less flexibility in tissue effect and a larger thermal zone.

Original languageEnglish
Title of host publicationLaser-Tissue Interaction VI
Number of pages8
Publication statusPublished - 22 May 1995
Externally publishedYes
EventLaser-Tissue Interaction VI 1995 - San Jose, United States
Duration: 1 Feb 19958 Feb 1995

Publication series

NameProceedings of SPIE - the international society for optical engineering
ISSN (Print)0277-786X


ConferenceLaser-Tissue Interaction VI 1995
Country/TerritoryUnited States
CitySan Jose
OtherWorkshop at Photonics West 1995


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