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Proceedings Paper

Some new aspects of the dose in laser therapy
Author(s): Lars Hode
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Paper Abstract

One of the most important factors in laser therapy is the dose. In the literature we find that the dose usually is defined as the amount of energy applied to 1 cm2 of skin. In this presentation we will look closer on what we mean with "dose" and what happens to the energy brought into the tissue. What is the dose 1 cm down in tissue? Should the unit instead be joules per cm3, or, would it be better using joules per mm3. In a blood vessel under an illuminated square centimeter of skin, we might perhaps use joules per ml. The light gives both local effects on cells and tissue and systemic effects - which is the most dominating? The energy that we feed into the tissue will cause a three dimensional light intensity distribution with different values in different points. In a static situation we will have the same dose distribution growing linearly with exposure time. In the case of coherent light illumination, a three dimensional speckle field is created and locally the energy density is varying a lot from point to point, causing field gradients. In some points of the illuminated volume, the dose might be so high that retarding effects may occur while in other, the dose may be close to zero. The situation is different for in vitro situation, for treatment of open wounds, for entering the light via a fiber in a syringe, for using super pulsed light sources etc. For wavelengths with very low tissue penetration the situation is different.

Paper Details

Date Published: 28 February 2006
PDF: 6 pages
Proc. SPIE 6140, Mechanisms for Low-Light Therapy, 614003 (28 February 2006); doi: 10.1117/12.640925
Show Author Affiliations
Lars Hode, Swedish Laser-Medical Society (Sweden)


Published in SPIE Proceedings Vol. 6140:
Mechanisms for Low-Light Therapy
Michael R. Hamblin; Ronald W. Waynant; Juanita Anders, Editor(s)

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