Lasers in Medical Science

, Volume 29, Issue 3, pp 973–978 | Cite as

Thermal relaxation times: an outdated concept in photothermal treatments

  • M. J. Murphy
  • P. A. Torstensson
Original Article


Thermal relaxation times were introduced into modern skin-laser science with the inception of selective photothermolysis. As a result, laser pulsewidths were determined according to the thermal relaxation times of the tissue targets. The Arrhenius Damage Integral shows that this approach is incorrect. The important parameter is the time required to induce irreversible protein denaturation within the target. This time is determined by the tissue’s intrinsic structure, not its physical dimensions. This report explains why thermal relaxation times should not be considered when treating many skin conditions with lasers or IPL systems.


Photothermal Relaxation time Arrhenius equation Protein denaturation Lasers IPL Vessels 


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Copyright information

© Springer-Verlag London 2013

Authors and Affiliations

  1. 1.DermaLase Training ServicesGlasgowUK
  2. 2.Photonova of Sweden ABV FrolundaSE

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