WHAT IS LASER POWER AND HOW DOES IT AFFECT PHOTOBIOMODULATION (PBM)?
THE LASER LIGHT ENERGY IS MEASURED BY THE LASER POWER Power seems simple but simply stating the output power does not relate the whole story when discussing therapy laser treatment. Not only is power important, but also the size of the area that is being treated. Power units for a laser are defined as watts (abbreviated as W). Power is a measure of the number of photons (light energy) emitted from the laser each second (the rate of energy delivery). Early therapeutic lasers had very low powers (less than 0.5 W) and very small beam areas (or spot sizes); consequently, early studies were often disappointing because the low powers were not able to provide sufficient number of photons to reach deeper affected tissue in vivo as doses that were optimised in vitro did not account for light’s losses as it penetrates through skin, fat, muscle, etc. WHY ARE HIGHER POWERS NEEDED? Simply stated, the greater the number of photons delivered to the surface, the greater the number of photons at any tissue depth. There is a threshold, a minimum number of photons that are needed to “turn on” the therapeutic effects of laser light. Hundreds of scientific studies have been done in vitro and have characterised the dosages needed to achieve a cellular response with light. These studies provide a baseline for the amount of laser energy needed to achieve results at the cellular level. PBM therapy is non-invasive; the light is applied to the surface of the skin. Some of that light is reflected by the skin or absorbed by other chromophores that are not associated with the injured cells and therefore do not contribute to PBM. Sufficient dose needs to be applied to the skin so that despite these losses sufficient dose reaches the target tissues, where PBM then may occur. Power (W) is a measure of the number of photons (light energy) emitted from a laser each second. Higher powers are needed as the greater the number of photons delivered to the surface, the greater the number of photons at any tissue depth. With higher powered lasers, it is possible not only to apply the benefits of PBM superficially, but also to treat a greatly expanded range of conditions.
The figure illustrates, with infrared images, the amount of light seen on the back of the hand when laser light is applied to the palm at 1 watt, 5 watts, and 10 watts of power. The greater the power, the greater the penetration to deeper tissue for a given amount of time. With higher powered lasers, it is possible to not only apply the benefits of PBM superficially, but it is also possible to treat a greatly expanded range of conditions by delivering a clinically effective quantity of photons to cells deep within the tissue. Lightforce Therapy lasers not only have the ability to delivery higher power for various conditions, but they also incorporate delivery systems that can efficiently treat tissue in a way that is comfortable to the patient.
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