Mechanisms of laser-induced thermal coagulation of whole blood in vitro

T. Joshua Prefer, Bernard Choi, Gracie Vargas, Karen M. McNally, A. J. Welch

Research output: Chapter in Book/Report/Conference proceedingChapter

6 Scopus citations

Abstract

Quantitative data regarding photothermal and damage processes during pulsed laser irradiation of blood are necessary to achieve a better understanding of laser treatment of cutaneous vascular lesions and improve numerical models. In this study, multiple experimental techniques were employed to quantify the effects of single-pulse KTP laser (λ = 532 nm, τ p = 10 ms) irradiation of whole blood in vitro: high-speed temperature measurement with a thermal camera in line-scan mode (8 kHz); optical coherence tomography (for determination of coagulum morphology); and transmission measurement with a co-aligned laser beam (λ = 635 nm). Threshold radiant exposures for coagulation (4.4-5.0 J/cm 2) and ablation (approximately J/cm 2) were identified. Thermal camera measurements indicated threshold coagulation temperatures of 90-100 °C, and peak temperatures of up to 145 °C for sub-ablation radiant exposures. Significant changes in coagulum thickness and consistency, and a corresponding decrease in transmission, were observed with increasing radiant exposure. The Arrhenius equation was shown to produce accurate predictions of coagulation onset (using appropriate rate process coefficients). The significance of dynamic effects such as evaporative loss and dynamic changes in optical properties was indicated. Implications for numerical modeling are discussed. Most importantly, the threshold temperatures typically quoted in the literature for pulsed laser coagulation (60-70 °C) and ablation (100 °C) of blood do not match the results of this study.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
PublisherSociety of Photo-Optical Instrumentation Engineers
Pages20-31
Number of pages12
Volume3590
StatePublished - 1999
Externally publishedYes
EventProceedings of the 1999 Lasers in Surgery: Advanced Characterization, Therapeutics, and Systems IX - San Jose, CA, USA
Duration: Jan 23 1999Jan 24 1999

Other

OtherProceedings of the 1999 Lasers in Surgery: Advanced Characterization, Therapeutics, and Systems IX
CitySan Jose, CA, USA
Period1/23/991/24/99

    Fingerprint

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

Cite this

Prefer, T. J., Choi, B., Vargas, G., McNally, K. M., & Welch, A. J. (1999). Mechanisms of laser-induced thermal coagulation of whole blood in vitro. In Proceedings of SPIE - The International Society for Optical Engineering (Vol. 3590, pp. 20-31). Society of Photo-Optical Instrumentation Engineers.