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the therapeutic use of sunlight or optical radiation, including infrared, visible, and ultraviolet radiation; a branch of physical therapy. Luminous energy’s effect on man is determined by its intensity (strength of the source and distance to the irradiated surface), by the duration of irradiation, and by the penetration depth of electromagnetic waves. The penetration depth, which depends on the light-wave length, is greatest with infrared and visible rays and least with ultraviolet rays. Erythema, that is, redness of the skin, may appear a few minutes after irradiation, for example, by infrared rays, or two to eight hours after exposure to ultraviolet rays. The intensity of the skin reaction varies with such factors as age, the time of year and the sensitivity of the skin in different parts of the body to different kinds of rays. It can change with some pathological conditions and after the ingestion of certain medicinal substances. The irradiated area acquires a tan in three to four days.
Thermal and luminescent artificial light sources are used in phototherapy. Thermal sources include incandescent lamps that emit infrared and visible rays, general and local light baths, Minin lights, and infrared rays. The quantity and composition of the energy released by these sources depend on the temperature of the radiating body. Luminescent sources, in which radiation is achieved by electrical, chemical, and other processes, include mercury-vapor lamps, luminescent erythematous lamps, and arc bactericidal lamps.
Ultraviolet irradiation, both local and general, is used to compensate for an ultraviolet-radiation insufficiency and to increase resistance to various infections, for example, influenza. It is used as an analgesic and antiphlogistic in treating diseases of the joints, the peripheral nervous system (neuritis, neuralgia, radiculitis), the muscular system (myositis), and the respiratory system (bronchitis, pleurisy), as well as in treating skin diseases, gynecologic and metabolic disorders, and some forms of tuberculosis. Ultraviolet irradiation is used in pediatrics in preventing rickets and acute respiratory diseases, in increasing the body’s defensive mechanisms against rheumatic fever between attacks, and, together with antirheumatics, in treating rheumatic fever during its acute phase. Thermal procedures and visible and infrared rays are used as analgesics and resorption agents primarily in treating subacute and chronic inflammatory diseases, neuralgia, and muscular pains.
Phototherapy is contraindicated in treating the active form of tuberculosis, neoplasms, pronounced heart failure, the second and third stages of hypertension, acute exhaustion, increased thyroid function, renal disease and insufficiency, and photopathy (a diseased condition caused by light).
T. M. KAMENETSKAIA