At the 2002 NAALT conference a Standards Committee was instructed to develop a working document that will define specific terminology and provide a basic outline of important concepts related to low level laser therapy and phototherapy.

Concept

The following concepts were defined in an attempt to clarify terminology and treatment approaches for clinical practice and research. This will allow users of phototherapy to replicate clinical/research findings as well assist in further development and promulgation of this technology worldwide.

Name

Previously the term low level laser therapy (LLLT) or other similar names have been used. Recent changes in technology in the field now require a broader term to more accurately reflect all forms of electromagnetic radiation being used for therapeutic applications. The terms Photobiomodulation (PBM), phototherapy and photon therapy have been recommended. The terms are defined as the use of non-ionizing electromagnetic radiation predominantly within the red and infrared part of the electromagnetic spectrum to assist in healing and pain relief. Phototherapy can either stimulate or inhibit cell activity.

Phototherapy is a broad term that encompasses, but is not limited to, the following five major categories of electromagnetic radiation:

1. low level laser therapy
2. other sources of narrow band radiation (LED/SLD)
3. broad band radiation
4. photo dynamic therapy (PDT)
5. polarized radiation

This report deals solely with low level lasers and other narrow band electromagnetic radiation.

Properties of Laser Radiation

Laser radiation has two characteristics that collectively differentiate it from other forms of radiation:

Coherence - means that the photons are well ordered or they are connected with light waves that remain synchronized with one another over long distances. A narrow bandwidth is necessary for a high degree of coherence. Coherence is not lost within tissue due to the phenomenon of laser speckling. Laser speckles are maintained throughout the depth of penetration.

Monochromaticity - the radiation is of narrow bandwidth and therefore one color (if visible) and coherent.

Because only laser radiation is coherent, other forms of narrow beam (e.g. LED, SLD) radiation are not equivalent. Therefore the terms are not interchangeable.

Electromagnetic Spectrum

Penetration

The depth to which phototherapy is effective depends upon the wavelength and incident power. There is a relationship between penetration and absorption. The greater the absorption the less the effective depth of penetration.

Mechanism of Action

In order for phototherapy to produce any effect the energy must be absorbed. Absorption of photons induces specific cellular responses depending on the state of the tissue in which the cells reside. Cell sensitivity differs in healthy and injured tissue being greater in the latter. All cells can absorb visible red light and infrared radiation.
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(Based on a discussion with Dr. R. Lubart, she indicated that all cell can absorb both visible and infrared radiation).

Response is based on photochemical effects in cells and tissues. Following absorption a cascade of cellular effects occurs. These include the development of reactive oxygen species, ATP synthesis, cell permeability changes and nitric oxide release. These can lead to increased cell proliferation, changes in extracellular matrix synthesis, and local effects on components of the immune, vascular and nervous system etc.

Dosemitry

Dose is often referred to as energy density (J/cm2) or fluence. However this does not provide sufficient information for clinical work and/or research studies to be replicated.

Energy density is an inadequate way to express dosage. By varying the irradiation time the same energy density can be achieved with widely different power densities some of which may be too low to be clinically ineffective and others so high as to be damaging.

It is essential to report the following:

• Power
  
• Power density
  
• Energy
  
• Energy density
  
• Irradiation time
  
• Beam spot size
  
• Wave length
  
• Irradiation mode (e.g. continuous or pulsed)
  
• If pulsed, pulse duration and space duration
  
• Treatment schedule

As the mechanisms of action are better understood, other parameters may become important.

There are a number of conditions that influence dose and phototherapy effect:

• Skin texture
  
• Color of skin
  
• Age
  
• Cell condition
  
• Medications
  
• General health of recipient
  
• Skin temperature

Treatment Guidelines

• Ensure area to be treated is clean and dry.
  
• Apply gentle pressure and position patient so that target can be most effectively irradiated.
  
• Apply gentle pressure to temporarily reduce blood flow locally adding penetration.

There are different approaches to delivering phototherapy. A segmental approach should be considered to increase the likelihood of effect. Based on the condition, treat all relevant areas, such as over:

• lesion or injury
  
• Referred areas
  
• Trigger/tender points
  
• Nerve roots or trunks
  
• Acupuncture points

It is important to measure outcomes and, if appropriate, to alter the delivery method and or treatment parameters.

Contraindications

The concept of "Contraindications" is a widely discussed issue among those utilizing phototherapy. As with any electromagnetic therapy modality, the specification of contraindications is based upon prudence more than hard experimental or clinical data. For the purposes of this paper, two categories are proposed: absolute and relative.

Absolute Contraindications

• Cancer (tumors or cancerous areas)
  
• Direct irradiation of eyes
  
• Photosensitivities. Patients treated with photosensitizes

Relative Contraindications

• Irradiation of the fetus or treatment over the pregnant uterus
  
• Over areas recently injected with corticosteroids
  
• Over the thyroid gland

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NAALT Standard Committee Members

Co-chairs
Anita Saltmarche - MedX Health Inc. Canada
M. Joyce Heinrich - T.A.B.S. Texas, U.S.A.

Members
Mary Dyson - Dyderm Ltd., KUMC U.K.
Ron Waynant - FDA U.S.A.
James Carroll - Thor International Ltd. U.K.
Chukuka Enwemeka - NYIT U.S.A