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Non-thermal laser question

Non-thermal Laser timings? Please could you tell me where I can get user friendly information to calculate the timings for laser (I have an old SPACE laser, which gives an average IR power output of 0.3mW, with a frequency of 700Hz (pulse width 200 nSec) and I just can not work out the equations.

I am trying to treat a tendon 1-2.5cm depth with a surface area of 5cm2.

Many thanks.

zoe vause

6 days ago

zoe vause

7 months ago

Back to General Electrotherapy

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Dr Ethne Nussbaum
Dr Ethne Nussbaum

Hi Zoe. If I am reading your question correctly, I believe that you have provided most the parameters mentioned by Cliff & from these you can calculate the time needed to treat at an energy density, say 4J/cm2. You did not report the area of the laser probe. Average power must be converted to W from mW for calculation.

In agreement with Cliff,
Energy Density (ED) = Power Density (PD) x time (sec).

PD = Average power / probe area (W/cm2).

Using your parameters , PD = 0.0003/probe area (W/cm2).

Thus, to deliver 4 J/cm2, time = 4 /PD (sec).

I presume that the 5cm2 that you mention is the approximate length of the tendon. I recommend that you approach the tendon from multiple aspects - not only along its 'top' edge but also probing from sides and to the extent that you can, accessing its under side, as one can in e.g. tendons at the wrist.

The average power of your device is so low that adequate treatment might not be feasible.

Last updated 5 months ago

Cliff Eaton
Cliff Eaton

Dear Zoe Sorry for the tardy response but the site was hacked into :( I would recommend that you look on the WALT (World Assoc of Laser Therapy) and use their recommendation. There appears to be a therapeutic window around 4J/cm2 to 20j/cm2 depending on the presentation. Lower values for acute applied more often and higher values for chronic less often. Energy is measured in Joules, which equate to Power (W) x Time (seconds). So once you have established the size of the area and dosage (J/cm2) you can work out how many joules are needed. Divide this by you 0.3W and you get the time in seconds Hope that helps Cliff

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