THERAPEUTIC LASER—Frequently Asked Questions (FAQ):
What is Low Level Laser Therapy?
Low-level laser therapy (LLLT) is a medical and veterinary treatment that uses low-level lasers or light-emitting diodes to alter cellular function. “Unlike other medical laser procedures, LLLT is not an ablative or thermal mechanism, but rather a photochemical effect comparable to photosynthesis in plants whereby the light is absorbed and exerts a chemical change. (Aimbire et al. 2006; Goncalves et al. 2007).”
What is the basis for LLLT action (FDA)?
LLLT is used in 3 main ways to:
i) Relieve acute and chronic pain
ii) Improve blood microcirculation, immune response, and tissue repair
iii) Reduce inflammation and edema
What is the basis for LLLT action (Health Canada)?
LLLT has now developed into a therapeutic procedure that is used in 3 main ways:
i) Reduce inflammation, edema, & chronic joint disorders
ii) Promote healing of wounds, deeper tissues, & nerves
iii) Treat neurological disorders & pain
Why level laser therapy not as “widely” low is accepted as other clinical modalities?
While low level laser therapy has been performed in Europe and Russia for many decades, the use of laser therapy in North America is relatively new. LLLT remains controversial as a therapy due to the variety of involved parameters that include wavelength, fluency, power density, pulse structure, and dose. Additionally, many of the underlying biochemical mechanisms are poorly understood, so it relies on empirical data.
Why do some studies fail to show LLLT positive outcomes?
“Failure in certain circumstances can be attributed to several factors including dosimeter (inadequate or too much energy delivered, inadequate or too much irradiance, inappropriate pulse structure, irradiation of insufficient area of the pathology), inappropriate anatomical treatment location and concurrent patient medication (such as steroidal and non-steroidal anti-inflammatories which can inhibit healing) (Admire et al. 2006; Goncalves et al. 2007).”
In addition, Chow (Dose Dilemmas in Low Level Laser Therapy- The Effects of Different Paradigms and Historical Perspectives, Laser Therapy Vol. 13 102); and Ortutay (Ortutay J, Mester A., Laser stimulation therapy in rehabilitation Proc. Laser Florence ‘97, 5th Congress EMLA, p. 22.) have also determined poor technique and expertise applying laser can significantly produce negative outcomes.
What is a Joule and what does it mean?
A Joule is a unit of energy. Energy (J) or energy density (J/cm2) is often used to describe LLLT dose. While there is strong evidence to suggest that the effectiveness of treatment varies greatly on both energy & power density used: there appears to be upper & lower thresholds of both parameters between which LLLT is effective – Arndt-Schultz Principle. Energy (J) or energy density (J/cm2) is often used as an important descriptor of LLLT dose, but this neglects the fact that energy has two components, power and time. Energy (J) = Power (W) X Time (s).
Using Joules as an expression of dose is potentially unreliable as it assumes a reciprocity relationship between irradiance and time.
If the Joule is inadequate for LLLT dosimetry, what should I be using?
Combining the fact that the Joule assumes a reciprocity relationship between irradiance and time, and that most devices do not measure in “real time” how much energy is being sent to the emitter; there is no way of knowing what the wattage is. All diodes fluctuate and regardless of what the diode are “rated” by the manufacturer. This is NOT what is physically sent to the diode. In addition, it does not take into account what energy is actually being absorbed into the target tissue. We know that up to 40% of infrared light can be reflected when the diode is not placed in direct contact with the skin.
Similarly, since any type of semiconductor emits light in a non-uniform matter (due to divergence), there is no way of actually knowing or measuring the “exact” spots size. [Class 4 complicates this because they do not use a uniform area of treatment; LiteCure "rolls" the emitter all around, while K-Laser has the emitter off the skin...and in an effort to not create a burn.] While power remains constant, power density is variable because of reflection and divergence due to non-contact.
This leaves two non-reliable measurements…trying to create a reliable measurement. So a joule is neither a quantifiable nor a qualitative measurement, and remains a relative dosing strategy. Since one cannot measure this amount of absorbed energy in the tissue or know the exact spot size, one should use a more reliable measurement. This unit is TIME. Time is always constant. [Multi Radiance Medical devices measure the output continually via an inbuilt reflector that measures what is being reflected off the skin. If this fails to measure appropriately, then the device does NOT work. Multi Radiance Devices can replicate outcomes by ensuring proper selection of frequency and time.]
What does Class mean, as there are some Class IV (4) lasers, some Class 3B lasers, & MRM lasers are Class 1M?
Class rating is strictly a safety rating. (FDA/Health Canada) the higher the Class rating, the more safety controls the user must have in place. Class rating does not reflect the efficacy of the treatment.
Laser safety is safe design, use and implementation of lasers to minimize the risk of laser accidents, especially those involving eye injuries. Since even relatively small amounts of laser light can lead to permanent eye injuries, the sale and usage of lasers is typically subject to government regulations.
“Moderate and high-power lasers are potentially hazardous because they can burn the retina of the eye, or even the skin. To control the risk of injury, various specifications, for example ANSI Z136 in the US and IEC 60825 internationally, define “classes” of laser depending on their power and wavelength. These regulations also prescribe required safety measures, such as labeling lasers with specific warnings, and wearing laser safety goggles when operating lasers.” — http://en.wikipedia.org/wiki/Laser_safety
Leading scientists on laser therapy (WALT, NAALT, ASP) do not approve the use of high power (Class 4, or Class IV, an older designation which some companies still use in marketing materials) lasers because there is simply no research. Too often in their marketing material (Appendix 3), Class 4 laser companies are intentionally misleading customers by NOT saying that all of the laser research they are referring to, was done on LLLT (by definition <500mW), not Class 4 (by definition >500mW).
As an example, here is a Class IV (4) article/study that LiteCure designed to show/read like a study, but the research cited it is based on LLLT lasers, not like their Class IV (4) laser.
WALT has dosage recommendation for safety reasons. The highest amount of joules used for a condition is around 40 Joules. http://www.walt.nu/dosage-recommendations-and-scientific-guidelines.html . As an example, one of the Class IV (4) lasers outputs 500-600 Joules in 1 minute and practitioners are instructed to use it for 2-5 minutes at a time.
Is pulsing (ISP, Pulse Mode) the same as “Super Pulsing”?
NO, they are not the same. Super Pulsed lasers have been researched and studied for 40 years. The high PEAK power of up to 25,000 mW is created by using ultra-short impulses of 80-100 nanoseconds (billionths of a second) in duration. Each an impulse generated is far below the coefficient of tissue relaxation: therefor no heat is transferred. This creates an average mean output of power similar to those of low level lasers, but very large peak energy densities.
When CW (continuous wave) lasers offer “pulsing”, it refers to duty cycle. A mechanical blocking or shuttering of the emitter light is used to “chop” the beam. This results in a radical decrease in the laser’s mean output of power. Class 4 lasers may offer a “pulse settings”, however the pulse duration is measured in microsecond as opposed to nanosecond. This is not Super Pulsing, and certainly not comparable to the MRM Super Pulsing LLLT.
What is the advantage of Super Pulsing in LLLT?
The advantages of Super Pulsing start with: depth of penetration, energy density, and safety. Depth of penetration is determined by the wavelength (905nm going the deepest) or color of the emitted laser. The high peak energy density insures adequate amount of light can dive deep into target tissues. Super Pulsed laser can be likened to a “Camera Flash” repeated in billionths of seconds. Treatment areas receive maximum photons with less tissue adaptive reaction, and at the same time have minimal tissue heating and maximal safety standards. Consider the hazard warnings for all Class IV (4) lasers, based on the Class IV (4) hazard of damaging the retina or burning tissue. It is obvious that something in the Class IV (4) HLLT technology that is excessive since the Class 1M MRM LLLT laser which does not require these excessive hazard preventions. Super Pulsing creates the highest photon density with the lowest thermal effect.
Does faster treatment lead to more effective treatment?
“Faster is better” is not justified in literature or in clinical trials. Reviewing the LLLT vs Class IV (4) papers from the International Dose Response Society, Section 6 , Summary and Conclusion, “LLLT delivered at low doses tends to work better than the same wavelength delivered at high levels”. There is no “simple” dose – as attractive as that notion is for a practitioner – no one size fits all because the parameters of laser therapy devices are diverse, as mentioned previously. Even emitters that are similar in power can have widely varying densities. A 10mW laser with a spot size of 10cm² produces only 1mW/cm², whereas a 10mW laser with a 1cm² spot size produces 10mW/cm². Considering only the mean power is a mistake confirmed by research.
There is a relationship between dose rate and the response. Optimal doses for biostimulation are .5 – 1 J/cm² for open wounds & 2 – 4 J/cm² when delivery is through the skin barrier. We know doses over 4 J/cm² are inhibitory; this has been shown time and again. Any research study that shows an effect on pain relief is primarily through photobioinhibition, and not through biostimulation. We cannot dose true biostimulation because that value changes with each patient and each individual condition. However, an inhibitory dose is easy, you pick a high dose, say 10J/cm2 and that will typically cause an inhibitory reaction in most patients.
NOTABLE FEATURES OF TQ & MR4 LASERS
- A synergistic effect is created by MRM’s use of Super Pulsing & several different wave lengths (905nm + 875nm + 660nm) + a static magnetic field. This cascading effect optimizes pain relief & accelerates healing. A sophisticated software algorithm allows the 660nm wavelength to be absorbed by superficial tissue, clearing the way for the infrared 875nm to penetrate deeper and eliminate cellular interference which allows the infrared 905nm Super Pulsed Laser to go even deeper, up to 4-5 inches.
- The Sweep Programs also help prevent tissue adaptation by scanning the target treatment area from superficial to deep tissues.
- The magnetic field (35-45mT) increases the efficacy of laser and light therapy. It does this by keeping the dipolar molecules disassociated, thus increasing the ratio of photon absorption by molecules. This is a patented concept.
- Super Pulsing. MRM’s proprietary & superior electronics achieve the fastest pulse durations in the range of 20ns. Faster pulse durations allow for faster photon absorption at the cellular and molecular levels.
- The most obvious of these superior features for a practitioner, is the LaserStim emitter with TARGET technology. LaserStim Target identifies the optimal treatment area by quickly locating biologically active points. It then calculates the dose for accurate, effective treatments. Visual & auditory feedback alerts the practitioner to these physiological changes.
- Hands-free treatment is possible by securing, for example, the LS50 Shower emitter, in an armature. The desk top devices have 2 (TQ) or 3 (MR4) ports & emitters can be run simultaneously, to shorten treatment time.
- Treatments: Average treatment times vary according to the condition or injury, acute or chronic and number of points to treat. A typical treatment may last 1-2 minutes per point and up to 5-10 minutes total.
In addition, the practitioner does not have to sacrifice technique with Multi Radiance Medical Technology. Static Applanation techniques such as “Over Pressure”, and “Wood Pecker”, as well as Pontinen’s and Ohshiro’s principles allow for optimal patient outcomes. This allows the practitioner to focus on delivering patient care without concern of too much radiation or too much heat.
Over Pressure: Allows the practitioner to press down on tissue to minimize bloodflow when trying to penetrate deep tissue.
Wood Pecker: Allows the practitioner to push and release against the lymphatic system to promote lymphatic drainage.
Pontinen’s Principle: A technique to treat trigger points and muscle spasms
Ohshiro’s Principle: A technique to treat swelling and edema
MRM lasers were developed for rehabilitation, not adapted from surgery applications. Its roots go back to the late 1970’s as a project of the Moscow Power Engineering Bureau. The Bureau was comprised of 2200-2400 highly educated people working on many different projects for the Ministry of Defense.
At the time all projects dealing with the Space Program were developed under the supervision or guidance of the Ministry of Defense. Here Ph.Ds. worked on new technologies that were designed to expedite the healing process of Cosmonauts in Space.
The project was not designed to be a business that would make a profit. Rather it was born of necessity to be able to help Cosmonauts with the inevitable body jarring injuries and pain caused by the turbulent effects of lift off and reentry into earth’s atmosphere. The constraints were apparent. Because of close quarters; the technology had to be compact and could not require an excessive power supply. The interior of the space cabins were not modern and risks were high, especially when performing such feats as connecting to the MIR space station.
No private company would have been able to afford the type of research and development costs that went into MRM Technology. The lasers were introduced commercially to the rehab marketplace in the 80’s. Now after over 20 years, there are approximately 400,000 Multi Radiance lasers in use worldwide!
TABLE 1. Parameters involved in determining the LLLT “medicine”
IRRADIATION PARAMETERS (The Medicine)
Irradiation Unit of
Parameter measurement Comment
Wavelength nm Light is electromagnetic energy which travels in discrete
packets that also have a wave-like property. Wavelength is
measured in nanometres (nm) and is visible in the 400-700nm
Irradiance W/cm² Often called Intensity, or Power Density, and is calculated as
Irradiance = Power (W)/Area (cm²)
Pulse structure Peak Power (W ) If the beam is pulsed then the Power should be the Average
Pulse freq (Hz) Power and calculated as follows:
Pulse Width (s) Average Power (W) = Peak Power (W) × pulse width(s) ×
Duty cycle (%) pulse frequency (Hz)
Coherence Coherence length Coherent light produces laser speckle, which has been
depends on postulated to play a role in the photobiomodulation
spectral bandwidth interaction with cells and subcellular organelles.
Coherent light is produced as a result of stimulated emission
(identical phase and time relationship)
Polarization Linear polarized Polarized light may have different effects than otherwise
or circular identical non-polarized light (or even 90-degree rotated
polarized polarized light). However, it is known that polarized light is
rapidly scrambled in highly scattering media such as tissue
(probably in the first few hundred μm).
TABLE 2. Parameters involved in determining the LLLT “dose”
IRRADIATION TIME OR ENERGY DELIVERED (The Dose)
Irradiation Unit of
Parameter measurement Comment
Energy (Joules) J Calculated as:
Energy (J) = Power (W) x time (s)
This mixes medicine and dose into a single expression and
ignores Irradiance. Using Joules as an expression of dose is
potentially unreliable as it assumes reciprocity (the inverse
relationship between power and time).
Energy Density J/cm² Common expression of LLLT “dose” is Energy Density
This expression of dose again mixes medicine and dose into
a single expression and is potentially unreliable as it assumes
a reciprocity relationship between irradiance and time.
Irradiation s In our view the safest way to record and prescribe LLLT is to
Time define the four parameters of the medicine (see table 1.) and
then define the irradiation time as “dose”.
Treatment Hours, days or The effects of different treatment interval is underexplored
interval weeks at this time though there is sufficient evidence to suggest that
this is an important parameter.
There are studies to indicate too much laser can produce DNA and enzyme damage, and cell aptoptosis and cytotoxicity.
- Hawkins D, Abrahamse H. Effect of multiple exposures of low-level laser therapy on the cellular responses of wounded human skin fibroblasts. Photomed Laser Surg. 2006 Dec;24(6):705-14
- Wu Q, Hamblin MR, et. al. Low-Level Laser Therapy for traumatic brain injury. Proc. of SPIE 2010, vol. 7552
Other important studies that clarify LLLT are listed below.
- The Nuts and Bolts of Low-level Laser (Light) Therapy
HOON CHUNG,1,2 TIANHONG DAI,1,2 SULBHA K. SHARMA,1 YING-YING HUANG,1,2,3 JAMES D. CARROLL,4And MICHAEL R. HAMBLINAnnals of Biomedical Engineering, Vol. 40, No. 2, February 2012 (_ 2011) pp. 516–533 DOI: 10.1007/s10439-011-0454-7
- Biphasic dose response in low level light therapy.Huang YY, Chen AC, Carroll JD, Hamblin MR. Dose Response. 2009 Sep1;7 (4): 358-83