Achilles Tendinopathy Toolkit: Section E - Low Level Laser Therapy Dosage Calculation

Original Editor - Kim Jackson for The BC Physical Therapy Tendinopathy Task Force:

Prof. Alex Scott, Dr Joseph Anthony, Dr Allison Ezzat, Prof Angie Fearon, JR Justesen, Dr Allison Ezzat, Dr Angie Fearon, Carol Kennedy, Michael Yates, Paul Blazey and Alison Hoens.

Top Contributors - Kim Jackson, Lucy Aird, Admin, Michelle Lee, Wanda van Niekerk and Rishika Babburu

Introduction[edit | edit source]

Low level laser therapy (LLLT) is a non invasive light source treatment that generates a single wavelength of light. It emits no heat, sound, or vibration and is used to treat various musculoskeletal conditions. It is believed to affect the function of connective tissue cells (fibroblasts), accelerate connective tissue repair and act as an anti-inflammatory agent. Lasers with different wavelengths, varying from 632 to 904 nm, are used in the treatment of musculoskeletal disorders.[1]

The World Association of Laser Therapy (WALT) provides dosage guidelines using Joules for various conditions. These
dosage guidelines are based upon the best evidence from the literature in conjunction with expert opinion.[2]

Physical Therapists are encouraged to set LLLT dose according to the WALT guidelines found via this link. (Note that the WALT guidelines are given for surface exposure.)

Low Level Laser Therapy Dosage Calculation[edit | edit source]

Current recommendations specify that LLLT dosage be provided in Joules (J, total energy), rather than the previous
recommended Joules/cm2 (J/cm2, energy density). Use Joules rather than Joules/cm2 to specify how much energy is
delivered in a treatment.

In Laser devices that do not calculate Joules automatically, dose can be determined in seconds of exposure required to give
the desired Joules by using the following calculation:

Joules = watts.seconds
Hence, Seconds = Joules/watts

LLLT Dosage Ex1.jpg

This change is very important clinically as the use of the previously recommended Joules/cm2 resulted in confusion when
comparing dosages between protocols. The resultant dose in Joules/cm2 could be the consequence of a number of
different treatment options.

LLLT Dosage Ex2.jpg

This example illustrates that using Joules/cm2 resulted in one patient receiving twice the total amount of energy that is
received by the other patient!

Therefore, all physical therapists using LLLT should be delivering dosages based on Joules rather than Joules/cm2.

Using Joules rather than Joules/cm2 will enable better standardization of dosage and permit comparison across different
treatment regimes.

Resources[edit | edit source]

References[edit | edit source]

  1. Cotler HB, Chow RT, Hamblin MR, Carroll J. The Use of Low Level Laser Therapy (LLLT) For Musculoskeletal Pain. MOJ Orthop Rheumatol 2015;2(5): 00068
  2. Bjordal JM. Low level laser therapy (LLLT) and World Association for Laser Therapy (WALT) dosage recommendations. Photomedicine and laser surgery. 2012 Feb 1;30(2):61-2.