Laser therapy dosing explained

So you've read about therapy lasers and decided to buy one for your practice. The rep comes in and trains your staff on how to use the laser. The built-in settings seem nice and practical, but you want to learn how to operate the equipment on your own.

Here are a few things you need to know about your laser and patient to get started.

Laser 101 

Treatment time: Your laser output is measured in watts (W). One watt is a joule per second (J/s). This determines the length of treatment.

Treatment area. This is measured in centimeters squared (cm2). A standard size playing card is 57 cm2. So for reference, I keep a card with my laser to help measure the treatment area. Your treatment area will vary based on the patient. 

Dosing guidelines

Keeping the above parameters in mind, let's figure out what we're treating. Treatment can be categorized by: a) deep or superficial, b) analgesia vs. anti-inflammatory and c) acute vs. chronic.

Based on these categories and academic research, the following guidelines for doses are:  

Putting it in practice

Now, let's apply what we've covered.  

You have the treatment area-for example, 300 cm2. You have a dose-let's say 10 J/cm2 for arthritis.

300 cm2 X 10 J/cm2 = 3,000 J

Let's say your laser puts out 12 W = 12 J/s

3,000/12 = 250 seconds, or just over four minutes

Since you don't want to deliver all 3,000 J to one aspect of the treatment area, I suggest using an overlapping grid technique (what would look like graph paper) to evenly distribute the 3,000 J in as many dimensions to that area as possible. For wounds this may be two dimensions, but for arthritic joints this can often be three dimensions. As you are doing this, keep an eye on your laser's timer to ensure that you're treating all planes and dimensions equally.

The condition's chronicity will also determine how often you repeat those 3,000 J. For acute conditions, this would ideally be once a day for three days, then every other day for three treatments, then twice a week until goals are met. This may also sync well with your wound care and bandage change schedule.

With more chronic conditions, I recommend three treatments during the first week, then twice a week until goals are met, then once a week. After that, I would continue to taper to the lowest effective dose. If an arthritis flare occurs, treat as an acute condition and then taper back down.

All of this information should be entered into the patient's medical record for proper tracking. Calculations for dosing photobiomodulation appropriately can be done quickly, easily and should correlate to the settings on your machine. 

References

1. Wardlaw JL, Gazzola KM, Wagoner A, et al. Laser therapy for incision healing in 9 dogs. Front Vet Sci 2019;5:349
2. Looney AL, Huntingforf JL, Blaeser LL, et al. A randomized blind placebo controlled trial investigating the effects of photobiomodulation therapy (PBMT) on canine elbow arthritis. Can Vet J 2018;59(9):959-966.
3. Millis D, Levine D. Canine rehabilitation and physical therapy. 2nd ed. Saunders, 2014. 

Dr. Matthew Brunke is a diplomate of the American College of Veterinary Sports Medicine and Rehabilitation and practices rehab, acupuncture and pain management at Veterinary Orthopedic & Sports Medicine Group (VOSM) in Annapolis Junction, Maryland.