Lasers in dermatocosmetology

Low-energy laser radiation is currently widely used in medicine. By its nature, laser radiation, like light, refers to electromagnetic oscillations of the optical range.

Laser (light amplification by stimulated emission of radiation) is a technical device that emits a directed focused beam of coherent monochromatic polarized electromagnetic radiation, i.e. light in a very narrow spectral range.

Properties of laser radiation

Coherence (from the Latin cohaerens - being in connection, connected) is the coordinated flow in time of several oscillatory wave processes of the same frequency and polarization, their ability to mutually strengthen or weaken each other when added together, i.e. coherence is the propagation of photons in one direction, having one oscillation frequency (energy). Such radiation is called coherent.

Monochromaticity is radiation of one specific frequency or wavelength. Monochromatic radiation is radiation with a spectrum width of less than 5 nm.

Polarization is the symmetry (or breaking of symmetry) in the distribution of the orientation of the electric and magnetic field strength vector in an electromagnetic wave relative to the direction of its propagation.

Directivity is a consequence of the coherence of laser radiation, when photons have one direction of propagation. A parallel light beam is called collimated.

The biological effect of laser radiation depends on its physical parameters, radiation power, dose, beam diameter, exposure time, and radiation mode.

Radiation power is an energy characteristic of electromagnetic radiation. The unit of measurement in SI is Watt (W).

Energy (dose) is the power of an electromagnetic wave emitted per unit of time.

Dose is a measure of the energy acting on the body. The SI unit of measurement is Joule (J).

Power density is the ratio of the radiated power to the false area perpendicular to the direction of radiation propagation. The SI unit of measurement is Watt/meter ² (W/m ^g ).

Dose density is the energy of radiation distributed over the area of the surface of exposure. The unit of measurement in SI is Joule/meter ² (J/m ² ). Dose density is calculated using the formula:

D = Рср x T/S,

Where D is the laser dose density; Pcp is the average radiation power; T is the exposure time; S is the exposure area.

There are several radiation modes: continuous - in this mode the power does not change during exposure; modulated - the radiation amplitude (power) may change; pulsed - radiation occurs over a very short period of time in the form of rarely repeating pulses.

To facilitate the work of a specialist with laser equipment, there are various tables for calculating the average radiation power depending on the area of irradiated tissue, the diameter of the light spot, the distance to the object, the exposure time, the radiation modes, the use of attachments. It should be noted that in each specific case, the specialist decides on the exposure parameters, taking into account the severity of the disease, the general condition of the patient, the capabilities of the laser device.

When calculating the dose, it is necessary to take into account that with the remote exposure method, about 50% of the energy is reflected from the skin surface. The reflection coefficient of the skin of electromagnetic waves of the optical range reaches 43-55%. In women, the reflection coefficient is 12-13% higher; In older people, the output power is lower than in younger people. The reflection coefficient in people with white skin is 42+2%; in non-dark skin - 24+2%. When using the contact-mirror method, almost all the supplied power is absorbed by the tissues in the exposure zone.

All lasers, regardless of their type, consist of the following basic elements: a working substance, a pump source, and an optical resonator consisting of mirrors. Medical laser devices have a device for modulating the radiation power for continuous lasers or a generator for pulsed lasers, a timer, a radiation power meter, and tools for delivering radiation to the irradiated tissues (light guides and attachments).

Classification of lasers (according to B.F. Fedorov, 1988):

1. According to the physical state of the laser working substance:
   • gas (helium-neon, helium-cadmium, argon, carbon dioxide, etc.);
   • excimer (argon-fluorine, krypton-fluorine, etc.)
   • solid-state (ruby, yttrium aluminum garnet, etc.);
   • liquid (organic dyes);
   • semiconductors (gallium arsenide, gallium arsenide phosphide, lead selenide, etc.).
2. By the method of excitation of the working substance:
   • optical pumping;
   • gas discharge pumping;
   • electronic excitation;
   • charge carrier injection;
   • thermal;
   • chemical reaction;
   • other.
3. By the wavelength of laser radiation.

The passport data of laser devices indicates a specific wavelength of radiation, determined by the material of the working substance. The same wavelengths can be generated by different types of lasers. At λ = 633 nm, the following lasers operate: helium-neon, liquid, semiconductor (AIGalnP), on gold vapor.

4. By the nature of the emitted energy:
   • continuous;
   • impulse.
5. By average power:
   • high-power lasers (more than 10 ³ W);
   • low power (less than 10 ^-1 W).
6. By degree of danger:
   • Class 1. Laser products that are safe under the intended conditions of use.
   • Class 2. Laser products generating visible radiation in the wavelength range from 400 to 700 nm. Eye protection is provided by natural reactions, including the blink reflex.
   • Class 3A. Laser products safe for viewing with the naked eye.
   • Class ЗВ. Direct observation of such laser products is always dangerous (the minimum observation distance between the eye and the screen should be at least 13 cm, the maximum observation time is 10 s).
   • Class 4. Laser products that produce hazardous scattered radiation. They may cause skin damage and fire hazard.

Therapeutic lasers belong to class 3A, 3B.

7. By the angular divergence of the beam.

Gas lasers have the smallest beam divergence - about 30 arc seconds. Solid-state lasers have a beam divergence of about 30 arc minutes.

8. By the efficiency coefficient (EC) of the laser.

Efficiency is determined by the ratio of the laser radiation power to the power consumed from the pump source.

Classification of lasers (by purpose of action)

• Multipurpose:
  • carbon dioxide (CO2) lasers;
  • semiconductor laser.
• For the treatment of vascular lesions:
  • yellow krypton laser;
  • yellow copper vapor laser;
  • neodymium YAG laser;
  • argon laser;
  • pulsed dye laser with flash lamp;
  • semiconductor laser.
• For the treatment of pigmented lesions:
  • pulsed dye laser;
  • green copper vapor laser;
  • green krypton laser;
  • Neodymium-YAG laser with frequency doubling and Q-switching.
• For tattoo removal:
  • Q-switched ruby laser;
  • Q-switched alexandrite laser;
  • Q-switched neodymium-YAG laser.
• For the treatment of skin lesions:
  • carbon dioxide laser;
  • neodymium - YAG laser;
  • semiconductor laser.

Low intensity laser radiation

The use of low-intensity laser radiation in dermatocosmetology as an auxiliary method, in the complex treatment of skin diseases, after surgical manipulations on the face allows painlessly, atraumatically to reduce the duration of exacerbations of the skin process, to achieve stable clinical remission.

Low-energy laser radiation has a multifactorial effect on the human body. Under the influence of laser radiation, changes occur that are realized at all levels of the organization of living matter.

At the subcellular level: the emergence of excited states of molecules, the formation of free radicals, an increase in the rate of synthesis of protein, RNA, DNA, acceleration of collagen synthesis, a change in oxygen balance and the activity of the oxidation-reduction process.

At the cellular level: change in the charge of the electric field of the cell, change in the membrane potential of the cell, increase in the proliferative activity of the cell,

At the tissue level: changes in the pH of the intercellular fluid, morphofunctional activity, microcirculation.

At the organ level: normalization of the function of any organ.

At the systemic and organismic level: the emergence of complex adaptive neuroreflex and neurohumoral responses with activation of the sympathetic-adrenal and immune systems.

The laser therapy (LT) method, used in clinical practice in recent years, has a universal multifactorial effect:

• analgesic and vasodilator;
• reduction of endogenous intoxication, antioxidant protection;
• activation of tissue trophism, normalization of nervous excitability;
• strengthening of bioenergetic processes;
• biostimulating effect on microcirculation (due to increased hemocirculation and activation of new collateral formation, improvement of rheological properties of blood;
• anti-inflammatory effect, also achieved by improving trophism, reducing hypoxia and swelling in the inflammation site, and enhancing regeneration processes;
• increased phagocytic activity of leukocytes;
• bactericidal action, has a bacteriostatic effect against staphylococcus, pseudomonas aeruginosa, proteus vulgaris, E. coli;
• normalization of cellular and humoral immunity, due to increased production of immune bodies and phagocytic activity of leukocytes;
• general desensitizing effect.

Against the background of laser therapy, the energy function of the skin is restored, the proliferation of fibroblasts is activated in the epidermis and dermis, cellular infiltrate is reduced in the dermis, and intercellular edema disappears in the epidermis.

Different types of lasers cause different reactions in biological tissue. The physical characteristics listed above provide the basis for choosing the type of laser from the entire variety of laser systems available in accordance with medical indications.

Indications for the use of low-intensity laser radiation

The main indication is the appropriateness of use:

• the need to stimulate blood and lymph circulation, regeneration processes;
• increased collagen formation;
• activation of the biosynthesis process.

Private indications:

• skin diseases - dermatitis, eczema, herpes infection, pustular diseases, alopecia, psoriasis;
• cosmetology problems - aging, wilting, sagging skin, wrinkles, cellulite, etc.

Contraindications to low-intensity laser therapy

Absolute:

• malignant neoplasms;
• hemorrhagic syndrome.

Relative:

• pulmonary-cardiac and cardiovascular insufficiency in the stage of decompensation;
• arterial hypotension;
• diseases of the hematopoietic organs;
• active tuberculosis;
• acute infectious diseases and febrile conditions of unknown etiology;
• thyrotoxicosis;
• diseases of the nervous system with sharply increased excitability;
• liver and kidney diseases with severe insufficiency of their functions;
• pregnancy period;
• mental illness;
• individual intolerance to the factor.

In dermatocosmetology, laser therapy is used in the form of:

1. external irradiation of lesions:
   • direct non-contact impact;
   • direct scanning effect;
   • contact local action of a rigid light guide;
   • using a contact-mirror attachment, applicator massager;
2. laser reflexology - impact on biologically active points (BAP);
3. irradiation of reflex-segmental zones;
4. transcutaneous blood irradiation in the area of projection of large vessels (NLBI);
5. endovascular blood irradiation (BLOCK).

When it is necessary to influence the patient with different physical factors, it is necessary to remember that low-intensity laser therapy is compatible and goes well with the prescription of basic drug therapy; with water procedures; with massage and therapeutic exercise; with the effect of a constant magnetic field; with ultrasound.

It is incompatible to prescribe several types of physiotherapy procedures on the same day if it is impossible to ensure the required time interval between them, which is at least eight hours; irradiation of the same area with ultraviolet radiation; laser therapy with the effect of alternating currents is unjustified; and laser therapy sessions are also incompatible with microwave therapy.

The effectiveness of laser therapy increases with the use of the following antioxidants (according to V. I. Korepanov, 1996):

• Rheopolyglucin, hemodez, trental, heparin, no-shpa (to improve microcirculation).
• Glucose solution with insulin (to replenish energy losses).
• Glutamic acid.
• Vitamin K, a regenerable lipid biooxidant.
• Vitamin C, a water-soluble antioxidant.
• Solcoseryl, which has antiradical activity and improves microcirculation.
• Vitamin E, a lipid antioxidant.
• Vitamin PP, involved in the restoration of glutathione.
• Pipolfen.
• Kefzol.

Technique and methodology of carrying out procedures

Laser irradiation is performed with both defocused and focused beams; remotely or by contact. Defocused laser radiation affects large areas of the body (the area of the pathological focus, segmental or reflexogenic zones). Focused laser beams irradiate pain points and acupuncture points. If there is a gap between the emitter and the irradiated skin, the technique is called remote; if the emitter touches the irradiated tissues, the technique is considered contact.

If the emitter does not change its position during a laser therapy session, the technique is called stable; if the emitter moves, the technique is called labile.

Depending on the technical capabilities of the laser device and the area of the irradiated surface, one of the following methods is used:

Method 1 - act directly on the affected area. This method is used to irradiate a small lesion (when the diameter of the laser beam is equal to or larger than the pathological lesion). Irradiation is performed using a stable method.

Method 2 - irradiation by fields. The entire irradiated area is divided into several fields. The number of fields depends on the area of the defocused laser beam. During one procedure, up to 3-5 fields are sequentially irradiated, not exceeding the maximum permissible total area of exposure of 400 cm ² (for the elderly 250-300 cm ² ).

Method 3 - laser beam scanning. Laser irradiation is performed using a labile method with circular movements from the periphery to the center of the pathological zone, affecting not only the affected area, but also healthy areas of the skin, capturing them up to 3-5 cm along the perimeter of the pathological focus.

When prescribing a laser procedure, the following must be reflected without fail:

• wavelength and mode of laser radiation generation (continuous, pulsed);
• in continuous mode - output power and energy irradiance (laser radiation power density);
• in pulse mode - pulse power, pulse repetition frequency;
• localization and number of impact fields;
• features of the methodological approach (distant or contact method, labile or stable);
• time of exposure no field (point);
• total irradiation time for one procedure;
• alternation (daily, every other day);
• total number of procedures per course of treatment.

It is necessary to take into account age groups, race, gender. It is recommended to conduct laser therapy sessions through an uncovered skin surface, however, irradiation through 2-3 layers of gauze is allowed. It is necessary to establish a rational place of exposure and an effective dose of radiation. For inpatients, a laser therapy session can be carried out twice a day; for outpatients - once a day. Preventive courses for chronic diseases are carried out four times a year.

Precautions when working with laser equipment.

1. Only persons who have completed specialization in laser medicine and after studying the operating instructions for the device are allowed to work with laser therapeutic devices.
2. It is prohibited to: turn on the unit with the ground disconnected, perform repair work with the unit turned on, work with faulty equipment, leave the laser unit unattended.
3. The operation of laser devices should be carried out in accordance with the requirements of GOST 12.1040-83 “Laser Safety”, “Sanitary Norms and Rules for the Installation and Operation of Lasers No. 2392-81”.
4. The main requirements when working with laser installations are to be careful and avoid direct and reflected laser beams getting into the eyes: turn on the laser in the "work" mode only after the emitter has stopped working on the impact zone; remove and move the emitter to another zone only after the laser has automatically switched off as a result of the timer being triggered. During a laser irradiation session, the staff and the patient must use special protective glasses.

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