Page 122 - Veterinary Laser Therapy in Small Animal Practice

108 Veterinary Laser Therapy in Small Animal Practice

Table 9.1 Recommended parameters for musculoskeletal conditions.
Example Dose (J/cm ) Power (W) Power density (W/cm )
2
2
Acute superficial Tendinitis 2–5 3–5 0.2–1
Acute deep Closed fracture 4–8 4–8 0.5–1.5
Chronic superficial Chronic tendinitis 4–15 4–6 0.5–1
Chronic deep Spondylosis, hip dysplasia 8–20 6–15 1.5–3

their own treatment energy calculated, i.e. if you were and the dose you want to apply. The AVERAGE
going to deliver 800 J to the stifle, do that and then power, not the peak power, will tell you how long
calculate what amount you would need for the spinal the treatment will take.
area. • What density of photons penetrates the surface:
this becomes even more important if our target
9.1.2 Power (W) tissues are not on the surface. When working with
musculoskeletal pain, though, we target not just
The power used usually ranges from 3 to 15 W, and deep articular surfaces of synovial membranes, but
as we explained in Chapter 7, it will influence the also more superficial nociceptors. This is good news,
following. since photon density will always be higher close to
the surface, and pain management usually requires
• How long it takes to treat an area: as for wounds, this higher dose, while tissue healing and inflamma-
decide in the first place the area you want to include tion will likely use less.

Calculating your treatment in four steps
1. Decide the dose (J/cm ) you will deliver, based on reference values and clinical progression of that particular
2
case.
2. Estimate or measure the treatment area (cm ).
2
3. Multiply those two values to calculate how many J you want to deliver in that session, in that area (J/cm ×
2
cm = J).
2
4. The average power you work with (W) will determine how long it takes to deliver those J (time in s = J/W).
Example
1. You have decided to deliver a dose of 10 J/cm over the thoracic and lumbar area of a dog.
2
2. The treatment area covers 40 cm from cranial to caudal, and 10 cm from side to side, so it has an area of 400
cm .
2
3. Therefore, you want to deliver a total amount of energy of about 4000 J in that session.
4. If we work with an average power of 1 W, it will take 4000 J/1 W = 4000 s (almost 67 min). Those same 4000
J using 12 W of average power will take 4000 J/12 W = 333 s or less than 6 min, and working with 10 W will
take slightly longer: 4000 J/10 W = 400 s (6.6 min).

If your device does not state the joules used, multiply the average power by the treatment time. By dividing those
final joules by the treatment area, you can then calculate the dose that is being delivered (J/cm ). For instance,
2
your device tells you it is going to treat the hip for 3 min (180 s). You know the average power it is using is 1
W. Then you can calculate that the amount of energy delivered is J = 1 W × 180 s, so it will deliver 180 J. In this
example, if you are treating a hip area of 180 cm with that program, you would only be applying 1 J/cm , which
2
2
is very insufficient.
This is one of the reasons why if you plan to treat musculoskeletal conditions or large surface areas, and you
want to scan them uniformly, a well-powered class IV laser is preferred over a lower power (or class of) device –
and why a 12 W device is more suitable than a 2 W one.

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