>> Infrared and ultraviolet radiation
§ 84 INFRARED AND ULTRAVIOLET RADIATION
Infrared radiation. Electromagnetic radiation with frequencies in the range from 3 10 11 to 3.75 10 14 Hz is called infrared radiation. It is emitted by any heated body, even when it does not glow. For example, radiators in an apartment emit infrared waves, causing noticeable heating of surrounding bodies. Therefore, infrared waves are often called thermal waves.
Infrared waves, which cannot be perceived by the eye, have wavelengths that are longer than the wavelength of red light (wavelength = 780 nm - 1 mm). The maximum radiation energy of an electric arc and an incandescent lamp comes from infrared rays.
Infrared radiation is used for drying paint coatings, vegetables, fruits, etc. Devices have been created in which the infrared image of an object, invisible to the eye, is converted into a visible one. Binoculars and optical sights are manufactured that allow you to see in the dark.
Ultraflight radiation. Electromagnetic radiation with frequencies in the range from 8 10 14 to 3 10 16 Hz is called ultraviolet radiation (wavelength = 10-380 nm).
Ultraviolet radiation can be detected using a screen coated with a luminescent substance. The screen begins to glow in the part on which rays falling beyond the flight region of the spectrum fall.
Ultraflight radiation is highly chemically active. Photo emulsion has increased sensitivity to ultraviolet radiation. This can be verified by projecting the spectrum in a darkened room onto photographic paper. After development, the paper will darken more at the flight end of the spectrum than at the visible end of the spectrum.
Ultraviolet rays do not cause visual images: they are invisible. But their effect on the retina and skin is great and destructive. Ultraviolet radiation from the Sun is not sufficiently absorbed by the upper layers of the atmosphere. Therefore, you cannot stay high in the mountains for a long time without clothes and without dark glasses. Glass glasses, transparent to the visible spectrum, protect the eyes from ultraviolet radiation, since glass strongly absorbs ultraviolet rays.
However, in small doses, ultraviolet rays have a healing effect. Moderate sun exposure is beneficial, especially in at a young age: Ultraviolet rays promote growth and strengthening of the body. In addition to the direct effect on skin tissue (formation of protective pigment - tanning, vitamin D 2), ultraviolet rays have an effect on the central nervous system, stimulating a number of important vital functions in the body.
Ultraflight rays also have a bactericidal effect. They kill pathogenic bacteria and are used for this purpose in medicine.
A heated body emits predominantly infrared radiation with wavelengths exceeding the wavelengths of visible radiation. Ultraflight radiation is shorter wavelength and has high chemical activity.
1. Why does sunlight passing through a window glass not cause a tan?
2. Do you know any source of ultraviolet radiation?
Ultraviolet radiation in medicine is used in the optical range of 180-380 nm (integral spectrum), which is divided into short-wave region (C or AF) - 180-280 nm, medium-wave (B) - 280-315 nm and long-wave (A) - 315- 380 nm (DUV).
Physical and physiological effects of ultraviolet radiation
Penetrates into biological tissues to a depth of 0.1-1 mm, is absorbed by molecules of nucleic acids, proteins and lipids, has photon energy sufficient to rupture covalent bonds, electronic excitation, dissociation and ionization of molecules (photoelectric effect), which leads to the formation of free radicals, ions, peroxides (photochemical effect), i.e. there is a sequential transformation of energy electromagnetic waves into chemical energy.
The mechanism of action of UV radiation is biophysical, humoral and neuro-reflex:
Changes in the electronic structure of atoms and molecules, ionic configuration, electrical properties of cells;
- inactivation, denaturation and coagulation of protein;
- photolysis - breakdown of complex protein structures - release of histamine, acetylcholine, biogenic amines;
- photooxidation - increased oxidative reactions in tissues;
- photosynthesis - reparative synthesis in nucleic acids, elimination of DNA damage;
- photoisomerization - internal rearrangement of atoms in a molecule, substances acquire new chemical and biological properties(provitamin - D2, D3),
- photosensitivity;
- erythema, with CUF it develops within 1.5-2 hours, with DUF - 4-24 hours;
- pigmentation;
- thermoregulation.
Ultraviolet radiation has an effect on the functional state various organs and human systems:
Leather;
- central and peripheral nervous system;
- autonomic nervous system;
- the cardiovascular system;
- blood system;
- hypothalamus-pituitary-adrenal glands;
- endocrine system;
- all types of metabolism, mineral metabolism;
- respiratory organs, respiratory center.
The healing effect of ultraviolet radiation
The reaction from organs and systems depends on the wavelength, dose and method of exposure to UV radiation.
Local irradiation:
Anti-inflammatory (A, B, C);
- bactericidal (C);
- painkiller (A, B, C);
- epithelializing, regenerating (A, B)
General exposure:
Stimulating immune reactions (A, B, C);
- desensitizing (A, B, C);
- regulation of vitamin balance “D”, “C” and metabolic processes (A, B).
Indications for UV therapy:
Acute, subacute and chronic inflammatory process;
- trauma to soft tissues and bones;
- wound;
- skin diseases;
- burns and frostbite;
- trophic ulcer;
- rickets;
- diseases of the musculoskeletal system, joints, rheumatism;
- infectious diseases - influenza, whooping cough, erysipelas;
- pain syndrome, neuralgia, neuritis;
- bronchial asthma;
- ENT diseases - tonsillitis, otitis, allergic rhinitis, pharyngitis, laryngitis;
- compensation for solar deficiency, increasing the stamina and endurance of the body.
Indications for ultraviolet irradiation in dentistry
Diseases of the oral mucosa;
- periodontal diseases;
- dental diseases - non-carious diseases, caries, pulpitis, periodontitis;
- inflammatory diseases of the maxillofacial area;
- TMJ diseases;
- facial pain.
Contraindications to UV therapy:
Malignant neoplasms,
- predisposition to bleeding,
- active tuberculosis,
- functional kidney failure,
- stage III hypertension,
- severe forms of atherosclerosis.
- thyrotoxicosis.
Ultraviolet radiation devices:
Integrated sources using DRT (mercury arc tube) lamps of various powers:
ORK-21M (DRT-375) - local and general irradiation
- OKN-11M (DRT-230) - local irradiation
- Mayachnye OKB-ZO (DRT-1000) and OKM-9 (DRT-375) - group and general irradiation
- ON-7 and UGN-1 (DRT-230). OUN-250 and OUN-500 (DRT-400) - local irradiation
- OUP-2 (DRT-120) - otolaryngology, ophthalmology, dentistry.
Selective short-wave (180-280 nm) use bactericidal arc lamps (BA) in the glow electric discharge mode in a mixture of mercury vapor and argon. Lamps of three types: DB-15, DB-30-1, DB-60.
Irradiators are produced:
Wall mounted (OBN)
- ceiling (OBP)
- on a tripod (OBSh) and mobile (OBP)
- local (BOD) with lamp DRB-8, BOP-4, OKUF-5M
- for blood irradiation (AUFOK) - MD-73M "Isolde" (with low pressure lamp LB-8).
Selective long-wave (310-320 nm) use fluorescent erythema lamps (LE), 15-30 W, made of uveolian glass with an internal phosphor coating:
Wall-mounted irradiators (OE)
- suspended reflected distribution (OED)
- mobile (OEP).
Beacon-type irradiators (EOKS-2000) with a xenon arc lamp (DKS TB-2000).
An ultraviolet irradiator on a tripod (OUSH1) with a fluorescent lamp (LE153), a large beacon ultraviolet irradiator (OMU), a tabletop ultraviolet irradiator (OUN-2).
Low pressure gas discharge lamp LUF-153 in the UUD-1, UDD-2L units for Puva and therapy, in the UV irradiator for the limbs OUK-1, for the head OUG-1 and in the irradiators EOD-10, EGD-5. Units for general and local irradiation are produced abroad: Puva, Psolylux, Psorymox, Valdman.
Technique and methodology of ultraviolet therapy
General exposure
Carry out according to one of the following schemes:
Main (from 1/4 to 3 biodoses, adding 1/4 each)
- slow (from 1/8 to 2 biodoses, adding 1/8 each)
- accelerated (from 1/2 to 4 biodoses, adding 1/2 at a time).
Local irradiation
Irradiation of the affected area, fields, reflexogenic zones, staged or by zone, extrafocal. factional.
Features of irradiation with erythemal doses:
One area of skin can be irradiated no more than 5 times, and the mucous membrane - no more than 6-8 times. Repeated irradiation of the same area of skin is possible only after the erythema has subsided. The subsequent radiation dose is increased by 1/2-1 biodose. When treating with UV rays, light-protective glasses are used for the patient and medical staff.
Dosing
Dosing of UV irradiation is carried out by determining the biodose, the biodose is the minimum amount of UV radiation sufficient to obtain the weakest threshold erythema on the skin in the shortest time, with a fixed distance from the irradiator (20 - 100 cm). The biodose is determined using a BD-2 biodosimeter.
There are different doses of ultraviolet radiation:
Suberythemal (less than 1 biodose)
- erythema small (1-2 biodoses)
- medium (3-4 biodoses)
- large (5-6 biodoses)
- hypererythemal (7-8 biodoses)
- massive (over 8 biodoses).
For air disinfection purposes:
Indirect radiation for 20-60 minutes, in the presence of people,
- direct radiation for 30-40 minutes, in the absence of people.
3. Ultraviolet and infrared radiation. Positive and negative effects on the body.
Ultraviolet radiation.
Ultraviolet radiation is the portion of solar radiation with a wavelength between 10 and 400 nm.
Ultraviolet rays with wavelengths from 10 to 290 nm do not reach the earth's surface. The properties of ultraviolet radiation at different wavelengths are not the same. The shortest waves (from 10 to 200 nm) in their effect are close to ionizing radiation. This area was named ozonizing. The energy of ultraviolet radiation with a wavelength from 200 to 400 nm is not sufficient to excite atoms; photochemical reactions.
For us highest value has a part of the spectrum from 200 to 400 nm. This zone is divided into
area C - from 200 to 280 nm
area B - from 280 to 320 nm
area A - from 320 to 400 nm
Area C called bactericidal. The predominant effect of ultraviolet radiation in this area is its bactericidal effect, which is widely used to disinfect water, air, etc. Areas B and A also have a bactericidal effect, but to a much lesser extent.
Area B called erythema, because under the influence of ultraviolet radiation in this area, erythema occurs. In area B it is also very pronounced vitamin-forming effect. The region with a wavelength from 265 to 315 nm has the most powerful vitamin-forming effect.
Area A got the name tanned. Under the influence of ultraviolet radiation in this area, tanning occurs - the formation of melanin, which is a protective reaction of the body.
Role of UFI very big. It increases the tone of the body, mental and physical performance, resistance to infections, stimulates the activity of the endocrine glands, and hematopoiesis.
Under the influence of ultraviolet radiation, vitamin D, histamine, tissue hormones, and pigments are formed.
Lack of ultraviolet radiation negatively affects the body and can lead to:
1. Rickets in children
2. Reducing general immunological reactivity
3. Decreased mental and physical performance
4. Increased incidence
5. Disorders of calcium metabolism (due to lack of vitamin D) - osteoporosis, osteomalacia, caries
However, we should not forget about the negative effects of ultraviolet radiation, which Lately close attention is paid.
Negative effects of overexposure:
1. Exacerbation of a number of chronic diseases. Therefore, tanning cannot be recommended for diseases such as tuberculosis, rheumatism, stomach and duodenal ulcers, cardiovascular diseases, all types of tumor processes
2. The role of ultraviolet radiation in development has been proven skin cancer, in particular melanomas
3. Perhaps the emergence of a shortage some aromatic amino acids - tyrosine, phenylalanine, as well as vitamin C and vitamin PP, which are involved in the synthesis of melanin
4. The quantity increases peroxide compounds, which leads to excessive consumption of protein and iron and the formation radiomimetics - compounds with mutagenic effects.
5. Possible occurrence photochemical burn in the case when the protective pigment does not have time to form. A photochemical burn is characterized by fever, headache, and malaise.
6. Excessive exposure to ultraviolet radiation may cause photoophthalmia - conjunctivitis, accompanied by redness, a feeling of sand in the eyes, burning, lacrimation, photophobia, and sometimes temporary loss of vision. Photoophthalmia is possible not only under the influence of direct, but also reflected and scattered light and can be observed in climbers, skiers, electric welders, in photographic rooms, and operating rooms. In industrial conditions (for example, welders), when the cornea is damaged by intense ultraviolet radiation, cataracts may develop.
7. Photosensitivity - increased sensitivity to ultraviolet radiation, which manifests itself in photoallergic reactions such as urticaria, dermatitis, eczema. For photosensitivity to occur, as a rule, the presence of both exogenous and endogenous factors is necessary. Endogenous factors include diseases of the thyroid, pancreas, liver, and enzyme pathies leading to the accumulation of porphyrins, fatty acids, and bilirubin. Exogenous factors - various chemical agents - tar, asphalt, creosote oil, fuels and lubricants, dyes (acridine, creosote).
Infrared radiation.
Infrared radiation is part of solar radiation in the wavelength range from 670 to 3400 nm.
Infrared study has primarily a thermal effect. In addition, a number of biological effects have now been established.
The thermal effect is determined primarily by the wavelength. Lengthnew wave Part of the infrared radiation (more than 1400 nm) is retained by the surface layers of the skin, due to which they warm up and a burning sensation appears. Due to this effect, the long-wave part of the radiation is called "scorching rays" With sufficient radiation intensity, erythema and burns are possible.
Shortwave Some of the radiation penetrates tissue to a depth of about 3 cm, as a result of which it can cause heating of tissue, including the meninges. It is the influence of short-wave infrared radiation that causes such a phenomenon as sunstroke. In addition, it causes overheating and clouding of the lens, which leads to the development of cataracts.
General reactions in response to the action of infrared radiation are characterized by hyperemia, increased gas exchange, increased excretory function of the kidneys, and changes in the functional state nervous system.
The section of physiotherapy in which dosed exposure to optical (infrared, visible and ultraviolet) radiation on the body is used for therapeutic purposes is called veterinary therapy or phototherapy.
Any body at a temperature above absolute zero emits electromagnetic waves. At a temperature of 450-500 o C, electromagnetic radiation consists only of infrared rays. A further increase in temperature causes the emission of visible light - red and white heat. At temperatures above 1000 o C, ultraviolet rays appear.
The sun is a powerful natural source of light. At the boundary of the earth's atmosphere, about 50% of its radiation is in the infrared region of the spectrum, approximately 9% in the ultraviolet region, and most of the remaining radiation is in the visible wavelength range.
Artificial thermal (caloric) emitters use filaments heated electric shock. They are used as sources of infrared and visible light. For these sources (incandescent lamps emitting infrared and visible rays; general and local electric light baths; Minin lamps and infrared ray lamps - infraruge), the amount and composition of the emitted energy depend on the degree of heating of the emitting body.
To obtain ultraviolet (and visible) radiation in physiotherapy, fluorescent mercury-quartz, fluorescent erythema and arc bactericidal lamps are used.
The effect of light energy on the human body is determined by its intensity (power of the source and distance to the irradiated surface); the duration of irradiation and the depth of penetration of electromagnetic waves, which depends on the length of the light wave. The longer the wavelength, the greater the penetration depth and the stronger the radiation effect. This depth is greatest for infrared and visible rays and smallest for ultraviolet rays (approximately 20, 10 and 1 mm, respectively). Redness of the skin - erythema - may appear a few minutes after the start of irradiation (for example, with infrared rays) or after a latent period (2-8 hours) when exposed to ultraviolet rays.
Infrared radiation penetrates deeper into the body's tissues than other types of electromagnetic waves, which causes heating of the entire thickness of the skin and partly the subcutaneous tissues. The therapeutic use of infrared radiation is based on its thermal effect. The greatest effect is achieved by short-wave infrared radiation, close to visible light. In this case, the surface layers are heated to a greater extent. The therapeutic effect is precisely due to the resulting temperature gradient, which activates the activity of the thermoregulatory system. Increasing the blood supply to the irradiated area leads to favorable therapeutic consequences: the reverse development of inflammatory processes is accelerated, tissue regeneration and local resistance are increased.
Thermal procedures using visible and infrared rays are used primarily as an analgesic and absorbent agent, mainly for subacute and chronic inflammatory processes, neuralgia and muscle pain. Violation of the rules for carrying out procedures can lead to dangerous overheating of tissues and the occurrence of thermal burns of the first and even second degree, as well as overload of the circulatory system, which is dangerous in case of cardiovascular diseases.
A broad class of processes occurring under the influence of visible light are photoperiodic processes. All life activity of living organisms is periodic. Every day, wakefulness is replaced by sleep, physical activity is replaced by rest, etc. IN natural conditions It is the lighting regime, the ratio of the duration of day and night that is the most important synchronizer of daily and annual biological rhythms of life.
White light(range of electromagnetic waves of visible radiation), consisting of 7 colors: red, orange, yellow, green, blue, indigo, violet with wavelengths from 760 to 400 nm, has the ability to penetrate the skin to a depth of 1 cm. However, light does not affect the body acts mainly through the visual analyzer - the retina. The perception of visible light and its color components has an indirect effect on the central nervous system and thereby on the mental state of a person. Yellow, green and orange colors have a beneficial effect on a person's mood; blue and purple are negative. It has been established that red and orange colors stimulate the activity of the cerebral cortex, green and yellow balance the processes of excitation and inhibition in it, blue inhibits neuropsychic activity. These properties of light should be taken into account when coloring interiors.
Visible radiation has a shorter wavelength than infrared rays, so its quanta carry higher energy. However, the influence of this radiation on the skin is carried out mainly by infrared and ultraviolet rays adjacent to the boundaries of its spectrum, which have thermal and chemical effects. Thus, in the spectrum of an incandescent lamp, which is a source of visible light, there is up to 85% infrared radiation.
Develops successfully and fundamentally new method light therapy using quantum generators emitting non-scattering beams of homogeneous light in the visible range. This makes it possible to use a laser beam in surgery in the form of a “light scalpel,” and in ophthalmology to “weld” the retina when it is detached. With an unfocused laser beam, light energy absorbed by cells and tissues has an active biological effect. This type of irradiation is successfully used for degenerative-dystrophic diseases of the spine, rheumatoid arthritis, long-term non-healing wounds, ulcers, polyneuritis, arthritis, bronchial asthma, stomatitis.
Ultraviolet radiation lies in the wavelength range from 10 to 400 nm and in its chemical activity significantly exceeds all other parts of the light spectrum. At the same time, ultraviolet rays have the smallest penetration depth into tissue - only up to 1 mm. Therefore, their direct influence is limited to the superficial layers of the irradiated areas of the skin and mucous membranes. The skin on the surface of the body is most sensitive to ultraviolet rays, the skin of the extremities is the least sensitive. Thus, the photosensitivity of the skin on the back of the hands and feet is 4 times lower than the skin of the abdomen and lumbar region. The skin of the palms and soles is the least sensitive. Sensitivity to ultraviolet rays is increased in children, especially at an early age.
Ultraviolet rays with wavelengths less than 200 nm are strongly absorbed by all bodies, including thin layers of air, and therefore are not of particular interest to medicine. The rest of the UV spectrum is divided into three regions: A (400-315 nm), B (315-280 nm) and C (280-200 nm). Short-wave radiation from the C-region changes the structure of proteins and lipids and has a bactericidal effect. Medium-wave radiation of the B-region has an antirachitic and pigment-forming effect, stimulates regeneration processes in organisms. Long-wave A-region rays cause luminescence of some organic matter, have a weak biological effect. Ultraviolet irradiation of the body increases the activity of protective mechanisms, normalizes blood clotting processes, and improves lipid (fat) metabolism. Under the influence of ultraviolet rays, the functions of external respiration improve, the activity of the adrenal cortex increases, the supply of oxygen to the myocardium increases, and its contractility increases.
Only large doses of ultraviolet radiation have a harmful effect on the human body. The use of ultraviolet rays for medicinal purposes with a well-selected individual dose and strict control provides a high therapeutic effect for many diseases. It consists of analgesic, anti-inflammatory, desensitizing, immunostimulating, and restorative effects.
Indications for the use of ultraviolet radiation are acute and chronic diseases joints, respiratory organs, female genital organs, skin, peripheral nervous system, wounds (local irradiation), as well as compensation for ultraviolet deficiency in order to increase the body's resistance to various infections, hardening, and tuberculous bone lesions. In pediatrics, this type of light therapy is used to prevent rickets, acute respiratory diseases, increase the body's defenses in the inter-attack period of rheumatism, and in combination with antirheumatic medications - also in the acute phase of the disease.
The main contraindications to the use of optical radiation in therapy are the active form of tuberculosis; tumors (benign or malignant) or suspicion of their presence; severe heart failure; hypertension stages 2-3; increased thyroid function; kidney diseases with insufficient function, as well as photopathologies (i.e. diseases caused by light).
The germicidal effect of ultraviolet light is widely used to irradiate areas of the body containing infection; for sterilization of various items; disinfection of water and food, etc.
In biological research, microscopes are often used, where ultraviolet rays are used instead of visible light, resulting in an increase in the resolution of the device, i.e. the ability of a microscope to produce separate images of small details of the object being examined.