Lateral Epicondyle Tendinopathy Toolkit: Section G - LASER Dosage Calculation

This article is currently under review and may not be up to date. Please come back soon to see the finished work! (22/11/2022)

Original Editor - Cindy John-Chu for The BC Physical Therapy Tendinopathy Task Force:

Dr. Joseph Anthony, Paul Blazey, Dr. Allison Ezzat, Dr. Angela Fearon, Diana Hughes, Carol Kennedy, Dr. Alex Scott, Michael Yates and Alison Hoens

Top Contributors - Cindy John-Chu, Evan Thomas, Kim Jackson, Admin, Wanda van Niekerk, Lucy Aird and Vidya Acharya

Introduction[edit | edit source]

Laser

Low level laser therapy (LLLT) is an electrotherapy modality used in the management of a broad spectrum of musculoskeletal conditions. It serves to stimulate healing, promote pain relief, manage inflammation and enhance the restoration of function in affected tissues[1].

Dosage of LLLT[edit | edit source]

LLLT, like other electrotherapy modalities, is required to be delivered at a certain dosage to produce its therapeutic effects. However, current recommendations specify that the dosage of LLLT be provided in Joules (J, implying total energy), rather than the previously recommended Joules/cm2 (J/cm2, which denoted energy density). Therefore, the use of Joules rather than Joules/cm2 is advocated to specify how much energy is delivered in a treatment.

Calculation of Dosage[edit | edit source]

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

  • Joules = watts.seconds
  • hence, Seconds = Joules/watts
LET Dosage LLLT Example 1.jpg


The recommendation to use Jules instead of Joules/cm2 is 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. The example in the table below further illustrates this stance.

LET Dosage LLLT Example 2.jpg

The example in the table above 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. To reiterate, using Joules rather than Joules/cm2 will enable better standardization of dosage and permit comparison across different treatment regimens.

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. Physical Therapists are encouraged to set LLLT dose according to the WALT guidelines.

Resources[edit | edit source]

References[edit | edit source]

  1. Avci P, Gupta A, Sadasivam M, Vecchio D, Pam Z, Pam N, Hamblin MR. Low-level laser (light) therapy (LLLT) in skin: stimulating, healing, restoring. Semin Cutan Med Surg. 2013 Mar;32(1):41-52.