Lasers in Medical Science

, Volume 10, Issue 1, pp 9–12 | Cite as

Laser pulse duration must match the estimated thermal relaxation time for successful photothermolysis of blood vessels

  • J. Stuart Nelson
  • Thomas E. Milner
  • Lars O. Svaasand
  • Sol Kimel
Original Articles


The relationship between photothermal damage to blood vessels of diameter,d, and laser pulse duration,tp, was verified in a series of studies using the chick chorioallantoic membrane (CAM). A total of 879 individual CAM blood vessels (d=50–130μm) was irradiated, using a laser pulse duration of 0.45 or 10 ms. Laser-induced vascular damage was observed in real time, recorded on videotape, and evaluated in a double-blind fashion. Permanent damage was confirmed by inspection 24 h after laser exposure. Under the conditions of this experiment, only when laser pulse durations are approximately equal to the estimated thermal relaxation times (τ) of the CAM microvessels can the critical core intravascular temperature, necessary to destroy vessels irreversibly, be achieved and sustained for sufficient time. Shorter pulse durations are more effective for damaging smaller blood vessels; conversely, longer pulse durations are more effective for damaging larger diameter vessels.

Key words

Blood vessel Laser Photothermolysis Port-wine stain Thermal relaxation time 


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Copyright information

© W.B. Saunders Company Ltd 1995

Authors and Affiliations

  • J. Stuart Nelson
    • 1
  • Thomas E. Milner
    • 1
  • Lars O. Svaasand
    • 1
    • 2
  • Sol Kimel
    • 1
    • 3
  1. 1.Beckman Laser Institute and Medical Clinic, Departments of Surgery and DermatologyUniversity of CaliforniaIrvineUSA
  2. 2.Division of Physical ElectronicsUniversity of Trondheim, Norwegian Institute of TechnologyTrondheimNorway
  3. 3.Department of ChemistryTechnion-Israel Institute of TechnologyHaifaIsrael

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