Thermographic analysis of the photochemical effect, a result of Multiwave Locked System Laser irradiation

Abstract

Laser therapy induces an active hyperemia in the irradiated tissues (increases blood vessel diameter and permeability). The initial assumption was that the magnitude of the vasodilator effect of laser therapy depends simultaneously on the irradiation dose (power, frequency), on the wavelength of radiation, as well as on the physiological characteristics of the irradiated tissues. It was thus assumed that the treatment of well-vascularized tissues would produce a vasodilator effect, expressed by higher local temperature than in poorly-vascularized tissues. In order to test this assumption, skin temperature variations were measured by means of digital thermography. A group consisting of 20 healthy volunteers was analyzed and temperature of relevant areas was measured before and after exposure to laser radiation at time 0 as well as at 30, 60 and 90 minutes of irradiation. The temperature gradient between the area concerned and the contralateral non-exposed area was calculated in each of these moments. Temperature variations could be observed in all the areas studied after exposure to radiation, both in the treated and in the contralateral areas. These temperature variations have the same trend (either increasing or decreasing) for the same anatomical area, treated or not, with thermal variations of different magnitudes (higher for the exposed area). The maximum value of temperature variations can be reached after 30 - 60 minutes, not at time 0, as it would be considered normal. Therefore, even though the energy transfer is considerable (the peak power for the pulsed emission of 3x25 W), the findings suggest that by irradiating living tissues with MLS laser is not achieved the photothermal effect, but photochemical effect is the stimulus that determines the formation of mediators with vasodilatory effects.

Key words:

laser therapy, MLS therapy, thermography, photochemical effect

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