Laser Terminologies – A Commentary

The truth and misconceptions with regard to the terms, “superpulsed” and “high-powered” in laser therapy.

Historically, a number of manufacturers utilize the adjectives, “superpulsed” or “high-powered” to describe the products they market. Their sales material is clearly designed to indicate that these terms make their systems superior to more appropriately powered devices. From our perspective, we support the distribution of systems where specifications are accurately stated and have proven to be consistently effective in the treatment of clinical pathologies.

The word “super” implies performance beyond normal. Within the context of laser terminology however, it merely indicates a short burst of energy delivered for a millisecond in time. Similarly, the word “high-power” creates the impression that higher levels of energy are better, but in practice, that is definitely not the case. Indeed, an excessive burst of energy can produce a significant inhibitory effect on cellular physiology and the integrity of tissue proteins, resulting in the prolongation of the period required to achieve healing. We comment on this type of misrepresentation in order that healthcare professionals planning to integrate laser technology into their practice, may obtain some clarity with regard to the confusing and misleading terminologies so frequently used.

One should also be aware that the parameters of light, including wavelength, frequency, duty cycle and other characteristics of diodes, such as superpulsed, cannot be patented. Only the physical design of the device delivering a light stream can be described in this manner. With regard to design, the optimal therapeutic dosage can be delivered when there is an accurate, consistent transfer of the photons generated into tissues. This permits the penetration of multiple layers and is the objective of the BioFlex System design.

What does superpulsed mean?

• Superpulsed refers to a pulsing technique, during the course of which the laser emits an emission train of high intensity for an extremely brief duration (nanoseconds). A number of superpulsed lasers exist which describe laser irradiation from low intensities for conventional Laser Therapy applied to tissues and extending to high intensities for the precise cutting of materials such as steel. A superpulsed carbon dioxide (CO2) laser is used for the purpose of vaporization of tissue in surgery. This type of high intensity, short duration pulsed laser produces minimal protein coagulation and results in reduced peripheral heating, while providing precise surgical incisions. In addition, it coagulates vascular channels facilitating homeostasis. Specifically this refers to a short, high intensity pulse, in order that the peak power can be much higher than the average power output of the light source. While there is a clear advantage to this method of application for surgical use, the physiological advantages of superpulsed lasers for Laser Therapy to be applied for tissue healing is unclear and has no established scientific basis.

What is a low-level superpulsed laser?

• Superpulsed lasers, made primarily with gallium-arsenide (Ga-As) or indium-gallium-arsenide (In-Ga-As) laser diodes, emit light at a wavelength of 904-905 nm. Again, these laser diodes produce very brief pulses (200 ns) at high intensities (1-50 W) and extremely high frequencies (in the kilohertz range) with an average power of 60 mW (based on a 20 W Ga-As diode).

What are the differences between continuous wave, pulsed and superpulsed lasers?

• Superpulsed lasers can only operate at a particular wavelength, pulse width and high frequency. Continuous wave and conventionally pulsed lasers are available in a range of therapeutic wavelengths (600-1000 nm) and can be modulated in an extensive number of pulse widths, frequencies and waveforms. The ability to change a wide range of parameters permits an optimally designed therapy program, personalized for each patient.

• While the peak output power of a superpulsed laser may be high (up to 50 W), the average output power is in the same range as continuous wave and pulsed lasers (1-500 mW) but without the additional flexibilities available in parameter settings and therefore protocol modulation. The latter characteristics are considered to be the most essential features in the delivery of effective therapy.

Which type of laser provides the optimal therapeutic outcome?

• There is much clinical data and published research to support the therapeutic benefit of continuous wave and pulsed lasers at a range of wavelengths from 600-1000 nm. Currently, there are about three times as many peer-reviewed articles featuring the wavelengths 660, 830 and 840 nm, compared to those using 904 or 905 nm. To date, there have been no clinical studies carried out that compare the efficacy between continuous wave, pulsed or superpulsed lasers. The claim that superpulsed lasers are superior from a therapeutic perspective can therefore be termed as patently false.

Penetration versus absorption and its relevance from a therapeutic perspective

• The first law of photochemistry (Grotthuss-Draper law) states that a photon must be absorbed to produce a physiological effect. The wavelength of 904-905 nm, in the infrared spectrum, has a lower coefficient of absorption by cytochrome c oxidase, the most widely accepted target for laser emissions, compared to lasers operating at 660 nm (red) or 830-840 nm (infrared). The wavelength used by superpulsed lasers penetrates further due to the fact that it is not readily absorbed by the key target molecules. This in itself is a distinct negative feature. Moreover, the intensity of light drops off rapidly as it penetrates the tissue layers, which means that less photons are available for absorption at deeper levels. The density of photon absorption in relation to tissue depth has not actually been measured for any wavelength. This would clearly indicate that greater depth penetration, the result of minimal absorption occurs but clearly cannot result in a significant therapeutic benefit.

Are shorter treatment times as effective as longer ones?

• Treatment times with superpulsed lasers anecdotally are shorter than those with continuous wave or pulsed lasers. Whereas shorter treatment times may seem to be convenient, there are a number of disadvantages which again make this type of treatment application less effective.

Longer treatment times confer distinct benefits: i.e.,

• The longer the period of laser application (duration), the greater the degree of the stimulatory dosage and its extension into the deeper tissues (cascade effect).

• The systemic benefits, including the stimulation of the immune system and the development of angiogenesis are time dependent and therefore related to the duration of application. These benefits are not obtained from the application of superpulsed lasers.
Needless to say, the two features described above are integral to effective therapy.

Meditech continues to conduct independent clinical research and monitor the literature with regard to all laser devices produced. Until research dictates otherwise, the company will continue to operate utilizing red (660 nm) and infrared (830 and 840 nm) diodes which have proven to be consistently effective in over one million treatments delivered to date. “Res ipsa loquitur” – the results speak for themselves.

It should be evident that extensive dermal wounds, stenosis of the spinal canal and many systemic diseases are beyond the scope of effective treatment using superpulsed laser devices and by extrapolation, it may be deduced that these systems are inefficient in treating other pathologies.

It is interesting to note that a laser manufacturer recently distributed a document comparing their product with the BioFlex System, one that states that the latter device “penetrates minimally”. This is not a scientific comment and is completely erroneous and misleading. In 1998, research carried out under our auspices in conjunction with Ryerson University in Toronto, demonstrated depth of penetration with laser diodes to extend over 20 cm. This is further supported by researchers in Sweden where penetration of 22 cm was found to be the established norm utilizing suitable laser diodes.

No concrete evidence has been presented at any time that the company publishing this incorrect data has a laser that penetrates to this level. Readers should always beware of statements that are not supported by some form of scientific evidence. Furthermore activities of this type, not only detract from the historic lack of veracity prevalent in the industry, but potentially harm companies that operate under legitimate guidelines. At Meditech, we choose to counter inappropriate advertising by publishing the truth based on science, as part of our educational process.

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