Page 51 - Chapter 3 - Laser/IPL Hair Removal

Chapter 3 – Fundamentals of Laser/IPL Hair Removal 2nd Edition
When Anderson and Parrish chose the TRT as the laser pulse duration, they were ONLY considering the heat conduction to the adjacent tissues. They did NOT consider the time needed to kill the target cells sufficiently - the ‘cooking’ time.
So, their choice was based, purely, on saving the tissues around the target, and not on actually destroying the target cells.
We can calculate the cell denaturation time (the cooking time) using an equation developed by the Swedish Nobel-prize laureate physicist, Svante Arrhenius. We have done a lot of work using this equation to try and understand the physical processes which occur in photothermal treatments.
Table 9 - The relaxation time is not the same as the denaturation time
We wrote a paper on this topic back in 2013 (published in the journal ‘Lasers in Medical Science’, 29 (3), 973-978 – you can see it here...
We are planning to write more on this topic soon.
In it, we discuss the Arrhenius equation (more information in Appendix 7) and how it applies to hair removal treatments. It has proved to be a very popular paper and has been read more than 12,000 times by other researchers across the planet, to date.
Thermal relaxation time
Denaturation time
The cooling time of the hot targets
The cooking time required to destroy the target cells
________________________________________________________________________ 51 Chapter 3, Ed. 2.0 Laser/IPL Hair Removal
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