For those of us who don’t have a PhD in laser physics, the terminology and science of therapy lasers can be overwhelming. By focusing on a couple of key concepts and definitions, however, anyone can learn how to talk about laser therapy like a pro.
The word laser is an acronym that stands for “Light Amplification by Stimulated Emission of Radiation.” There are 3 properties that make laser light unique: monochromatism, coherence, and collimation. These properties are in part what makes laser light suitable for therapy purposes.
Monochromatism is an especially important feature of lasers because it has to do with the color, or in other words, the wavelength of the laser. Different wavelengths are absorbed at varying levels by different structures and fluids in the body. Certain wavelengths are optimal for minimizing absorption into superficial structures while maximizing absorption into target tissues.
One of the most important words related to laser therapy is “photobiomodulation.” The easiest way to define this term is to look at its components. “Photo” refers to light, “bio” refers to life, and “modulation” indicates a change of some sort. So, when you read that the primary mechanism of laser therapy is photobiomodulation, this means that light energy is used to produce changes in living organisms.
Joules and Watts
Joules and watts are key components for determining a therapeutic dose. Dose is calculated by establishing target joules/cm2 that you want to deliver to a designated area of the body.
Laser therapy dosing is measured in joules/cm2. One watt is equal to 1 joule/second. So, if a therapy laser has 15 W of power, and the treatment is 1 minute long, that’s a total of 900 J delivered.
To determine total dosage, you need to know the size of the area being treated. If you are treating an area 10 cm x 10 cm (or 100 cm2) for a total of 1 minute at 15 W, then your total dose is 9 J/cm2.
To become even more versed in laser therapy lingo and see photobiomodulation in action, watch this animation: