Phototherapy (chromotherapy). Phototherapy is a therapeutic and prophylactic way of visible and infrared irradiation using. In the electromagnetic radiation spectrum, visible light occupies a wavelength range of 400 nm to 760 nm. The spectral composition of the visible light and the wavelengths corresponding to the primary colors are shown in Table 1.
Table 1. Spectral characteristics of the primary colors of visible light.
Up to 40% of the visible rays are reflected upon contact with the skin, and the rest penetrates to a depth of 1 mm (purple rays) to 3 cm (red rays). The patient’s sex, pigmentation level and skin color, the state of skin blood flow, as well as many medicinal substances can influence the reflection and absorption of light, so that should be considered in the complex therapy including the use of medicinal substances.When an object, e.g. a human body, is exposed to light, there are phenomena of reflection, refraction, and absorption observed. Only the absorbed part of the visible rays has a biological effect.
The light absorption is accompanied by the emergence of a number of physiochemical effects which directly depend on the energy of photons.
Visible radiation, which has photon energy of 150-300 kJ/mol, can lead to an increase in the energy of the vibrational processes of atoms and molecules, as well as to their excitation and photolytic dissociation. Subsequently, these primary physical processes are transformed into heat, lead to increased biological activity of molecules and the formation of primary photoproducts, which are a trigger mechanism for photobiological processes. These processes in total constitute the body’s reaction to the action of light.
The selective absorption of light by physiologically active molecules which play an important role in the processes of vital activity is an important part of the effect the visible light has on the body. For example, blue light acceptors in animal and human cells are flavins, cytochromes, bilirubin, carotene, neurosporin, and others. The acceptors of red light include catalase, molecular oxygen, cytochrome oxidase, and superoxide dismutase. Green radiation is selectively absorbed by flavoproteins and indolamines. The light absorption by these molecules is accompanied by a change in their spatial configuration, which affects their participation in physiological and pathological processes.
The physiological and therapeutic effect of chromotherapy depends on the wavelength (color) of the visible radiation used, which determines the differential approach to their therapeutic and prophylactic use.
Red light. Red light when exposed to the skin, acupuncture points, and pathological focus stimulates blood formation, positively affects the activity of the musculoskeletal system, kidneys and liver, inhibits the platelet aggregation. It improves regional circulation, causes vasodilation, the temperature increase in tissues, activates reparative processes, and eliminates congestive phenomena in tissues and organs. It possesses immunostimulating, anti-inflammatory, and analgesic effects.
Yellow light. Yellow light when exposed to the skin and pathological focus increases muscle tone, stimulates the lymph drainage, moderately reduces high blood pressure, and has analgesic and anti-edematous effect.
Green light. Green light when exposed to the skin and pathological focus reduces vascular tone, dilates capillaries, stabilizes blood pressure, enhances regenerative processes, has anti-inflammatory, sedative, antispastic, and antimicrobial effects.
Blue light. Blue light when used locally has a relaxing, anti-inflammatory, bactericidal, absorbable, anti-edematous, and analgesic effects and also stimulates proliferation and phagocytosis, enhances gas exchange, and reduces blood viscosity.
This data suggests that the best way to treat pain syndromes is to use red and yellow light; for the treatment of acute inflammatory processes and trauma firstly green and blue light, then red and yellow should be used; in chronic and dystrophic processes the red light should be used.
Infrared irradiation. Infrared irradiation is the use of infrared radiation (760 nm – 1 mm) with therapeutic and preventive and rehabilitation purposes. In physiotherapeutic practice, the infrared radiation of short-wave and partially medium-wave range (760 nm – 4000 nm) is mainly used.
When infrared rays hit the human body, some of them reflect (up to 60%), the other part is absorbed, and the third part passes through different layers of tissue. Short infrared rays are absorbed at a depth of about 1 cm, and longer infrared radiation penetrates 2 to 3 cm deeper.
In the absorption of infrared rays, which has low photon energy (about 100 – 120 kJ/mol), the amplification of vibrational and rotational motions of molecules and atoms is generally observed, as well as the acceleration of the motion of electrons along the orbits, which leads to the heat generation (therefore, infrared rays are called caloric or thermal).
The heat generation due to infrared irradiation leads to a local temperature increase in the exposed tissues by 1- 2 ͦ C and causes local thermoregulatory reactions. These reactions show as a change in the vascular tone (primarily the capillar) and the functional activity of thermomechanically sensitive afferent conductors of the blood. The vascular reaction is characterized by the following: after a brief spasm, there is hyperemia caused by the superficial vessels dilation and an increase in blood flow. Erythema caused by infrared rays (caloric photoerythema), has uneven patchy coloration, no clear boundaries, quickly disappears and does not leave appreciable pigmentation.
Heating of tissues is accompanied by an increased metabolism in those tissues, activation of diffusion processes, and increased migration of polymorphonuclear leukocytes and lymphocytes into the pathological focus. This contributes to the weakening of inflammation and the removal of cell autolysis products from the inflammatory area. Activation of peripheral circulation and changes in vascular permeability caused by infrared radiation contribute to the resolution of infiltrates and effusions, but also tissue dehydration, especially in subacute and chronic stages of inflammation. Infrared radiation stimulates the processes of reparative regeneration, most significantly in the final stages of the inflammatory process. Infrared rays increase the skin turgor, increase its permeability, activate collagen synthesis, stimulate the activity of sweat glands.
Irritation and changes in the impulse activity of thermoreceptors and other skin afferents underlie the neuroreflective reactions of internal organs located in the irradiation area. They are manifested in vasodilation and enhancement of the metabolism of internal organs, acceleration of reparation processes, normalization of their functional state, reduction of spasm of smooth muscles. Infrared irradiation of extensive areas of the body leads to increased respiration, increased sweating, activation of the thermoregulation centers of the hypothalamus, and increased release of biologically active agents, mainly vasoactive, which play an important role in the humoral regulation of general and regional blood flow.
Thus, the main therapeutic properties of infrared radiation determining indications for its use are the following: anti-inflammatory, reparative-regenerative, vasodilating, anti-edematous, and metabolic effects.
The characteristics of the optical polarized radiation of the visible and infrared ranges performed on the AndroSPOK magnetophotobarotherapy apparatus are shown in Table 2.
Table 2. The maximal intensity of the optical radiation is provided at the level of the lower edge of the electromagnetic inductor coil of the AndroSPOK apparatus.
Thus, magnetophototherapy is a well-grounded combination physiotherapy method, in which can not only potentiate the physiological and therapeutic effects of light and the magnetic field, but also create new physical and biological processes that enhance the effect of each of the combined physical factors. From the data given above it follows that magnetic fields and phototherapeutic factors are characterized not only by a number of identical therapeutic effects, but also by a similar action on various body systems and essential vital processes, which is a good reason for their combined use, i.e. the use of magnetophototherapy in the treatment of various diseases. It is known that the presence of similar physiological and therapeutic effects of two physical factors is almost always accompanied by synergism in their combined application. The combined use of light and a magnetic field may induce some new physical processes, which significantly affect the efficiency and possibilities of magnetophototherapy. The energy of photons affects weak intermolecular bonds, and the magnetic field contributes to this dissociation and at the same time prevents the recombination of ions during the combined exposure. In addition, magnetic fields provide a certain orientation to molecular dipoles, act as a kind of polarizer, which contributes to a deeper penetration of optical radiation into tissues, a decrease in its reflection at the tissue interface, and an improved absorption. This leads to an increase in the therapeutic effectiveness of phototherapy. The combined effect of light and magnetic field is more energy-intensive and more active than the isolated application of these two factors.