PHYSICAL AND TECHNICAL ASPECTS
OF LOW-LEVEL LASER THERAPY
In
a modern medicine, especially in Russia
and in a number of other Eastern European countries, different
physiotherapeutic methods of treatment and prevention of diseases are widely
used. These methods cover application of various natural or artificially created
physical healing factors and forces of mechanical, thermal or electromagnetic
nature. In the past 15-20 years special area among them was occupied by low-level
laser radiation (LLLR) due to such specific characteristics as
monochromatic and high spectral density of radiation power, coherence, what has
a result in a small divergence of light
ray, possibility of simple focusing (defocusing) and transporting of radiation
by optic lenses and mirrors, possibility of transmitting of light energy through
optic fiber, transparency of upper skin layers and mucous membranes of
man’s and animal’s organs
for LLLR
and so on. Such features of electromagnetic
radiation in the optic waveband after the invention of lasers (later - of light
diodes (LEDS) especially superluminescent ones with close technical
characteristics) could not be not noticed, and in a period of 1980-2000 besides
a laser surgery the intensive evolution of low-level
laser therapy (LLLT) had started in Russian medicine,
especially in physiotherapy. It was not less important that the laser
therapeutic apparatus is relatively primitive from the point of view of engineer construction, so it is easily reproducible by an engineer of middle
qualification. Moreover, with an appearance of semiconductor lasers they became small enough
as well as cheap, so any practical doctors could buy them and keep them at home.
For numerous Russian medical advisers and physicians in a period of crisis of
1990’s LLLT became fine additional tool for intensive private practice and an
additional source to earn money, that attracts much more attention to LLLT of
different medical specialists.
At
the same time, in serious literature, especially in developed European
countries,
Historically
LLLT appeared as extension of traditional techniques of light-healing in
physiotherapy, having a thousand-year history and traces back to teachings of
Hippocrates, Galen and Avicenna (sun light baths). On the eve of the XX-XXI
centuries LLLT is trying to include into itself some bright characteristics of a modern
time: terminology of quantum physics (LLLT is often called as quantum therapy
since light is not just an electromagnetic wave, but also is a flux of energy
quanta), terminology of radiation biology (concepts of radiation dose, sum dose,
radiation load), modern influence of Eastern philosophy and Eastern medical and
philosophical doctrine (laser acupuncture, laser correction using biological
activated points, using body's meridians), etc. But all of these, to our point of view, everything
of these in
LLLT goes lubberly and just brings a confusion into a
problem of initial mechanisms in LLLT and techniques of its practical use. Take
just
speculations
on
dosage
determination
in
LLLT! Recommended
values of power density and
energetic exposition ("dose") in different manuals on LLLT vary in
hundred times and more (correspondingly from 0,5 to 200 mW/cm2
and from 0,1 up to 120 J/cm2)". Besides that the dose
term (a key item in LLLT application!) in different publications has
different physical and technical meaning and is varied from surface power
density (W/cm2) to volume energy density (J/cm3). Note:
the dose in a modern physics, engineering, radiobiology, medicine (excluding
pharmacology) and a medical physics (if one wants to use this notation correctly) is
the energy of any type of radiation, coming to mass unit of exposed medium
(J/kg). All other parameters used by doctors as a slang "dose"
have different names, different physical units and different physical meaning.
And this confusion in terminology often brings to confusion in a problem of LLLT
action mechanisms. If a doctor speaks of LLLT mechanisms, resulting in
microcirculation growth, pain syndrome remission, homeostasis normalization
etc., then he speaks of derived effects, caused by organism response to LLLT
irradiation, not of the mechanisms of the laser light action itself. Physical
mechanisms (excluding the placebo "mechanism") are hidden deeper, if
they exist at all, in a photo-physics and a photo-chemistry processes of
interaction of laser light radiation and matter. According to the First Law of
photo-chemistry (Grotgus-Dreyper’s law), for example, only the absorbed light
causes a photo-chemical reaction. I.e. primary process in LLLT is absorption of
the photon by matter. What a molecule or a set of molecules absorbs energy and
which way they spend it (heating, dissociation of molecules, singlet oxygen
activation etc.), how this chain of photo-physical and photo-chemical processes
brings to the integral healing effect and to response in organism – what are
the problems of direct (or initial) mechanisms of LLLT. Development of
specialized physical and technical equipment and devices to register the
mentioned effects, organism's reactions and for accurate dosimetry in LLLT as
well as next medical and biological scientific investigations with the use of
these devices, new techniques of joint medical and physical studies may give
finally possibility to find out a presence or absence of the LLLT effect itself,
mechanisms of its initiation, more optimal parameters for its accomplishment,
etc. In other words, investigation of different physical and technical aspects
of LLLT is also very interesting, topical, to our opinion, and helps anyone to respond
to a number of important questions, rising on the way to the cogent clinical
application of the type of the physiotherapy technologies in medicine.
For more information see our publications:
1. Andrey V. Dunaev "Method and device used for testing of the absorbed dose of radiation during low level laser therapy". // Proc. SPIE, vol. 6440, 64400T (2007).
Have a look at it in PDF (237Kb)
2. Dunaev A.V., Gasparyan L.V. "The use of biological feedbacks and
methods of testing for light therapy". // Abstract book of 13th International
Congress of European Medical Laser Association "Laser Helsinki
2008" - Helsinki: EMLA, 2008.
Have a look at it in PDF (51Kb)
3. Rogatkin D.A., Tchernyi V.V. "Low level laser therapy: view from physicist on mechanisms of action and experience of application" // Collected papers "Interaction of radiation and matter". // Proc. of 2-nd Baikal's School on fundamental physics - Irkutsk: ISTU, 1999. - pp.366-378. (in Russian, with some adds of 2000-2008 years).
Have a look at Russian version in PDF (305Kb)
4. Shalobaev E.V., Leontyeva N.V., Monahov Yu.S., Efimenko A.V.,
Podmasteryev K.V., Dunaev A.V. "The use of biofeedback and tomography tools in
laser scanning physiotherapeutic settings". // Technologies of living systems
[Technologii jivih sistem] , vol. 6., No.4, 2009. - p.66-72 (in Russian).
Have a look at Russian version in PDF (1900Kb)
5. Rogatkin
D.A., Shcherbakov M.I., Makarov D.S., Bychenkov O.A. "Thermal-vision monitoring of
processes of heating and microcirculation of blood accompanying low-intensity
laser therapeutic procedures". // Journal of Optical Technology,
Vol. 78, No.10, 2011. - pp.666-671.
Have a look at it in PDF (914Kb)
See our more recent publications in www.medphyslab.com