Biodose is determined. Ultraviolet radiation in medicine, devices, indications, methods. Local ultraviolet exposure

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Dosimetry and dosing of ultraviolet radiation

In the practical work of medical and preventive and sanatorium-resort institutions, the following can be used:
1. UV radiometer "Ermetr", designed to measure the effective erythemal illumination of human skin and determine the dose of radiation from any artificial, as well as natural source of UV radiation, regardless of the latitude of the terrain and the state of the Earth's ozone layer.
2. UV radiometer ("UV-A", "UV-B", "UV-C"), designed to measure the intensity and dose of UV radiation in the spectral ranges A, B and C.
3. UV radiometer "Baktmetr", designed to measure the bactericidal UV illumination from bactericidal lamps.

All of the above radiometers consist of an electronic unit with a digital output and a photodetector head, the spectral sensitivity of which in different types of radiometers is corrected for tabulated sensitivity in accordance with WHO recommendations.

With the help of UV radiometers, it is also possible to determine the threshold dose of UV radiation required for subsequent therapeutic effects. For example, the average threshold erythema-forming dose (with a maximum sensitivity at 297 nm), according to some foreign standards (German Standard Din 5031, part 10) will be 250-500 J/m2.

However, in physiotherapy, to assess UV radiation, it is important to focus not only on physical quantities that reflect energy exposure or radiation intensity, but also take into account the nature of the biological effect caused by it. In this regard, the method (Dalfeld-Gorbachev) of assessing the individual photosensitivity of the skin to UV rays has become widespread in practice (Fig. 327). This method determines the minimum duration of exposure time required to obtain a threshold erythema skin reaction. One biological dose (biodose) is taken as a unit of measurement.

Biodose is most often determined from a distance of 90 or 50 cm from the lamp to the surface of the skin of the abdomen outward from the midline; biodose from irradiators such as "OH" or "BOP-4" (for irradiation of the nasopharynx) is determined on the inner surface of the forearm.

To assess the photosensitivity of the skin, a standard biodosimeter (“BD-2”) is used, which is a metal plate 100x60 mm with 6 rectangular windows (“holes” 25x7 mm each), closed by a flap moving from above. The biodosimeter is sewn into the oilcloth and has ribbons for fixing it on the patient's body.

Determination of biodose

The results of determining the individual photosensitivity of the skin are evaluated after 24 hours (in daylight), while the erythemal strip of minimal (in terms of color) intensity, but with clear edges, will correspond to the time of 1 biodose.

For example, when a biodosimeter was irradiated for 3 minutes (i.e., 30 s for each window), the irradiation time for the first window was 3 minutes, the second - 2 minutes, etc., and the sixth - 30 s. A day later, only 5 of 6 strips with decreasing (top-down) color intensity appeared on the skin of the abdomen, and the last (5th) strip with fuzzy ("blurred") edges. In this case, the 4th strip (with clear edges) and the corresponding biodose time, i.e. 1.5 minutes, should be taken as the threshold erythema skin reaction.

Depending on the task of the physiotherapist and the type of irradiator, UV irradiation is carried out from various working distances: 30, 50, 75, 100 cm. Based on the known biodose, if necessary, the arithmetic recalculation of the biodose to any required distance can be made using the formula:

X \u003d A * (B2 / C2) (min),

Where: X is the desired biodose per minute; A is the time in minutes and C is the distance in cm of the known biodose; B is the distance in cm from which irradiation is supposed to be carried out.

Example. Known biodose (from a distance of 50 cm) equal to 1 min. It is necessary to determine the biodose time from a distance of 100 cm. According to the formula, we find:

X = 4 min.

Therefore, the time of one biodose from a distance of 100 cm will be 4 minutes.

In outpatient practice, as well as for UV exposures that do not require delay (for example, with erysipelas, etc.), it is allowed to use the so-called "average biodose" for a particular irradiator. It is preliminarily determined (for each irradiator separately) in 10-12 practically healthy individuals, while the arithmetic mean of the time of the found biodoses will correspond to the time of the “average biodose” for this irradiator. "Mean biodose" is recommended to be determined every 3 months.

To determine the biodose of UV radiation in pediatric practice, the same method is used (Dalfeld-Gorbachev). Taking into account the high sensitivity of the child's body to UV rays, it is recommended to sequentially open the windows of the biodosimeter every 15 seconds (this should be done especially when determining the biodose in children during the first months and years of life). In children of school age, it is permissible to open the “holes” of the biodosimeter every 30 s.

The results of determining skin photosensitivity in children should be pre-evaluated 3-6 hours after irradiation (in a hospital) and finally - after 24 hours (in inpatients and outpatients). When implementing UV irradiation, it is also necessary to take into account the general condition of the child, the period of the disease, the nature of its course, the state of the protective and adaptive mechanisms of the body, and the light and climatic conditions of the child's life.

Technique for conducting ultraviolet radiation

General ultraviolet exposures

For group exposures, it is recommended to center the irradiator lamp on the chest, back, and for individual exposures, on the upper third of the thigh (when using the ORK-21M irradiator) or on the navel area (when using the EOD-10 irradiator). Depending on the type of irradiator, the distance from the source of UV radiation to the irradiated surface is 50-100 cm.

Before general individual irradiation, the photosensitivity of the patient's skin is determined. For group exposures, it is allowed to use the average biodose for a given irradiator. For general UV exposure, patients should wear light-protective goggles. Irradiation is carried out according to the schemes, starting with suberythemal doses (1/8, 1/4, 1/2 biodose). There are 3 generally accepted (exemplary) schemes for general UV irradiation (Table 7). The choice of scheme is determined by the general condition of the patient and (or) the nature of the disease. General UV irradiation is carried out daily or every other day, if necessary, the course is repeated after 2-3 months.

Table 7. Exemplary schemes of general UV exposures

Local ultraviolet exposure

Repeated irradiations of the same area of ​​the skin are usually carried out every other day (less often - after 2 days), different areas of the skin surface (taking into account their area) can be irradiated in one day. Repeated irradiations of the same field are carried out in an increasing (by 1-2 biodoses) dosage.

Due to the change in the optical properties of the skin, erythemal doses for the same area are prescribed repeatedly, but on average no more than 4-5 times. The number of local exposures using suberythemal UV exposure can be increased to 7-14. If indicated, a second course of erythemotherapy can be carried out no earlier than after 7-8 weeks, t. after restoration of the sensitivity of the irradiated areas of the skin to UV rays.

There are several ways of local irradiation: a) irradiation of the site (center) of the lesion (wound, trophic ulcer, etc.); b) extrafocal irradiation (repercussion technique) - exposure to a skin surface area symmetrical to the site of the lesion (for example, if there is a plaster cast on a sore leg, irradiation of a healthy leg); c) irradiation by fields (chest, along the nerve, etc.);

D) segmental irradiation of reflexogenic zones (collar zone, panty zone, Zakharyin-Ged zones, etc.); e) stage-nose irradiation (by zones-belts); c) fractionated irradiation, in which, in order to limit UV exposure over the area, a “perforated localizer” made of medical oilcloth with a size of 30x30 cm is used.

It cut 150-200 square holes with a side of 1 cm and at a distance of 1-2 cm from each other. Irradiation is carried out with erythemal doses through holes in the oilcloth placed on the patient's body. Two fields are irradiated in one procedure (chest, back). With fractionated irradiation of children, a perforated localizer is also used: for newborns - with 12 holes with an area of ​​0.5-1 cm2; for infants - from 40 and for older children - from 70-125 holes of the indicated area size.

Bogolyubov V.M., Vasilyeva M.F., Vorobyov M.G.

For the therapeutic effect of UV radiation, selective and integral artificial sources of ultraviolet rays are used. Selective sources emit long-wavelength or a combination of long- and medium-wavelength, and integrated sources emit all regions of the UV spectrum. For medicinal purposes, as a rule, selective sources are used. The LUV-153 gas-discharge lamp with the maximum spectral density of ultraviolet radiation in the long-wave range serves as a selective source of UV rays. It is used for PUVA-therapy in ultraviolet long-wave units UUD-1, UUD-1A, UFO 1500, UFO 2000, OUG-1 head irradiator, OUN-1 desktop irradiator, OUK-1 extremity irradiator, EDI 10 irradiator for individual and EHD 5 for group general exposures.

To obtain long-wave UV radiation, erythemal uviolet (with increased transparency in the ultraviolet region of the spectrum) LE-type burners (LE-15, LE-30, LE-60) are also used. Their inner surface is coated with a phosphor, which provides radiation in the range of 310 - 320 nm. Abroad, for general and local exposures, PUVA-22, Psorylux, etc. units are used. To obtain a tan, UV irradiation units are used (Fig. 17), which contain certain amounts of 100-R insolation reflector lamps, with a power of 80-100 W, for body tan. For face tanning, metal-halogen lamps with a power of 400 watts are used. Solariums such as Ergoline, Ketler, HB, SLT, Nemektron, etc. are used in medical institutions.

Rice. 17. Long-wave ultraviolet irradiation of the human body

Rice. 18. PUVA therapy

Before general irradiation, the patient's skin should be cleaned of ointments and creams. Different surfaces of the patient's body are irradiated alternately or simultaneously the whole body (Fig. 17,18), depending on the device model. With local exposure, the area of ​​the patient's body free from pigmentation is irradiated. The source of UV radiation should be at least 10 - 15 cm away from the body. During the procedure, the patient's eyes are protected with special goggles.

Dosing procedures depends on the intensity of radiation, the duration of exposure and the distance from the source of UV radiation. Table 2 shows the duration of UV exposure depending on the type of skin pigmentation.

table 2

Characteristics of general long-wave exposures

UV irradiation in the medium wave range carried out using integral and selective sources. Integral artificial sources emit all areas of UV radiation, selective - only long- and medium-wave UV rays or any part of the UV spectrum (short-wave, medium-wave or long-wave UV rays). The source of integrated exposure to UV rays is an arc mercury-quartz tube burner (DRT) with a power of 100 - 125 W (DRT-100, DRT-100-2, DRT-125), 230 - 250 W (DRT-230, DRT-250 P) , 400 W (DRT-400), 1000 W (DRT-1000). In the desktop quartz irradiator OKN-11 M (Fig. 19) and in the irradiator UGN-1 (OH-7) for group irradiation of the nasopharynx, a DRT-230 lamp is used, in a mercury-quartz irradiator on a tripod ORK-21-M (Fig. 20 ), OUSh, desktop OUN-250 and OUN-500, and for the nasopharynx OH-7, the DRT-400 lamp is used, in the lighthouse large UV irradiator OMU - DRT-1000. For intracavitary irradiation, a DRK-120 gas-discharge lamp is used in ultraviolet irradiators of gynecological (OUP-1), otolaryngological, ophthalmological and dental (OUP-2) profiles.

Rice. 19. Desktop ultraviolet irradiator "OKN-11": 1 - power switch, 2 - sockets for connecting the mains voltage, 3 - start button

Rice. 20. Ultraviolet irradiator "OKR-21M": 1 - mains switch,

2 - start button, 3 - connecting wire

Selective sources emitting long-wave and medium-wave ultraviolet rays are LE-15 (15 W) and LE-30 (30 W) erythemal luminescent lamps, which are made of uvio glass and coated with a phosphor from the inside. These lamps are used in wall-mounted radiators of the OE type, suspended and mobile irradiators - OEP. In a desktop ultraviolet irradiator, a fluorescent lamp LZ 153 is used, and in a beacon-type device (EOKS-2000) an arc xenon lamp is used - DKs TB-2000. Xenon refers to inert gases, the atmosphere of which is used in a xenon lamp, which is a gas-discharge (arc discharge) light source of high and extra high pressure. The lamp is a quartz flask (tubular or spherical) filled with xenon, with hermetically embedded electrodes. The emission spectrum of a xenon lamp is close to that of the sun.

Dosing procedures is usually carried out by the Gorbachev biological method using a BD-2 biodosimeter (Fig. 21). This method is based on the individual sensitivity of the skin to ultraviolet radiation. The unit of radiation dose is one biodose (dose of ultraviolet radiation over time), which causes minimal visible erythema at a certain distance from the radiation source.

The biodosimeter consists of a metal plate in which there are 6 rectangular holes 5 × 15 mm in size, located at a distance of 5 mm from each other. The plate has a sliding shutter that closes the holes. A biodosimeter with closed holes is fixed on the skin of the lower abdomen. The rest of the skin surface is closed from the action of UV radiation. The lamp is installed at a distance of 50 cm from the skin. Directing it to the biodosimeter, irradiation is performed for 60 seconds, sequentially opening one hole of the plate every 10 seconds. Therefore, the first hole is irradiated for 60 seconds and the last hole for 10 seconds. Since the erythema reaction does not appear immediately after irradiation, but after a latent period, the biodose is determined 12–24 hours after irradiation.

Rice. 21. (in the text - 21, in the folder with pictures - 22, the numbering is off).

Biodosimeter BD - 2

Determination of the result is reduced to the establishment of minimal erythema in the form of a pink strip with four clear corners. The biodose will be equal to the exposure time in seconds over this strip of skin.

Taking into account therapeutic tasks, irradiation is carried out from distances of 25, 50, 75 and 100 cm. In these cases, the dose is recalculated to a new distance. The degree of illumination of a surface is inversely proportional to the square of the distance from the light source. The calculation is made according to the formula:

Dr  D 0 (r x / r 0) 2 ,

where Dr is the biodose at the new distance, D 0 is the biodose determined at a distance (r 0) equal to 50 cm from the body surface, r x is the distance at which irradiation will be carried out.

Therefore, if the distance between the patient and the radiation source doubles, the biodose must be increased four times. When the distance is halved, the biodose is reduced by a factor of four (the squared distance rule).

The average biodose for a particular emitter is set according to the examination of 10-15 healthy individuals, determined quarterly and every time the burner or fluorescent lamp is changed.

According to the degree of intensity of local exposure, erythemal doses are used. Distinguish small erythema doses. equal to 1 - 2 biodoses, erythemal doses medium intensity within 3 - 4 biodoses, large erythemal doses - 5 - 6 biodoses and hypererythemal- over 8 biodoses. In some cases, it is important to determine the sensitivity of mucous membranes to UV radiation. For this purpose, the method of V.N. Tkachenko is used using the BUF-1 biodosimeter (Fig. 23), which is a plate with four holes. This plate is put on the tube of the irradiator and placed in contact over the nipple of the breast, where the sensitivity of the pigmented skin is close to the sensitivity of the mucous membranes. As with the Gorbachev method, the plate holes are opened at a certain interval equal to 30 seconds. Biodose is determined by minimal erythema.

Rice. 23. Biodosimeter BUF - 1.

General and local methods of UV irradiation in the medium wave range. General irradiation is carried out in suberythemal gradually increasing doses according to the chosen scheme of UV exposure: basic, accelerated or delayed (Table 3). Accelerated the scheme is used for skin diseases, slow- in the treatment of the elderly, debilitated patients and children. The anterior, posterior and lateral surfaces of the patient's body are irradiated alternately (Fig. 24). During the procedure, goggles are put on the patient's eyes. When carrying out UV irradiation according to the main scheme, the exposure begins with ¼ biodose, gradually adjusted to 3 biodoses. Sessions are held daily. The course of treatment is prescribed 20 procedures. At accelerated In the scheme, irradiation begins with a dose greater than in the main scheme, equal to ½ of the biodose, daily increasing by the same amount and adjusted to 4 biodoses. The course of treatment is prescribed 16 - 18 procedures. By slow On the contrary, the treatment regimen begins with a lower dose equal to 1/8 of the biodose, also increasing it daily by 1/8 and bringing it up to 2 - 2.5 biodoses. The course of treatment is 20 - 26 procedures. Repeated courses of general UV irradiation are prescribed after 2-3 months.

Table 3

Rice. 24. General ultraviolet exposure of the patient

Local exposures medium-wave UV rays are carried out using erythemal doses in areas of 200 - 600 cm 2 in adults and 50 - 200 cm 2 in children. Repeated irradiations of the same area are carried out as the erythema fades - after 1 to 3 days. Subsequent radiation doses exceed the previous ones by 0.5 - 1.0 biodoses (25 - 50%). The same area can be irradiated 3-5 times. However, irradiation of wounds, bedsores, mucous membranes is allowed up to 10 - 12 times.

There are 5 options for local UV irradiation. The first option is to directly affect the pathological focus, second– extrafocal exposure (irradiation symmetrically to a pathological part of the body or a distant zone, for example, the heel area with acute respiratory infections), third- irradiation of reflexogenic zones (collar area, panty zone, epigastric zone, etc.), fourth- irradiation in several fields, when the affected area exceeds the allowable (600 cm 2) single-stage exposure, fifth the variant consists in fractionated exposure using a perforated oilcloth with holes of 1 cm 2 (according to I.I. Shimanko) to increase the excitable segmental zones with increased sensitivity to UV rays. Medium-wave UV irradiation can be effectively combined with mineral or mineral-gas baths (balneophototherapy). Repeated courses of local UV irradiation are prescribed after 1 month.

For shortwave UV irradiation uses integrated sources: gas discharge lamps DRK-120 (intracavitary irradiators OUP-1 and OUP-2) and DRT-250 (for nasopharyngeal irradiation). A selective source of short UV rays are bactericidal arc lamps of the DB type: DB-15, DB-30, DB-60, the power of which is 15, 30 and 60 W, respectively. The source of radiation in them is an electric discharge in a mixture of mercury vapor with argon. These lamps are used in devices used for disinfection of premises: wall-mounted (OBN, OBRN), wall-ceiling (OBRNP), on a tripod (OBSH), mobile (OBP, OBOV, OBBR, OBB, OBBN).

Rice. 25. Irradiation of the nasal mucosa

Devices OKUF-5M (Fig. 25), BOP-4 (Fig. 26) and BOD-9 are used for short-wave irradiation of limited areas of the skin and mucous membranes. In them, the radiation sources are DRT-230 and DRB-8 lamps. When irradiating the nasal mucosa, for example, the emitter tube is inserted alternately into the vestibule of the right and left half of the nose, and when exposed to the tonsils, the radiation is directed alternately - first to one and then to the other tonsil (Fig. 27). The biodose is determined using a BUF-1 biodosimeter, as in the case of medium-wave UV irradiation.

Rice. 26. Portable bactericidal irradiator "BOP-4"

Rice. 27. Ultraviolet irradiation of the tonsils with an integral source

For UV irradiation of blood(autotransfusion of ultraviolet-irradiated blood - AUFOK) devices EUFOK, LK-5I, UFOK, MD-73M, Izolda, Nadezhda, Olga are used. UV irradiation of blood is carried out according to open and closed methods. open The technique consists in the fact that blood is irradiated in a pre-assembled quartz glass vessel with its subsequent return to the vascular bed. At closed In this method, blood is irradiated directly in a vein or when it passes through a special quartz cuvette isolated from the external environment using a peristaltic pump. The duration of blood irradiation is 10-15 minutes. The course of treatment is prescribed 6 - 8 procedures, which are carried out after 2 days. It is important to take into account the amount of irradiated blood - 1 - 2 ml per 1 kg of body weight. A second course of AUFOK is carried out after 3-6 months.

To obtain UV rays, fluorescent light sources are used, which are a DRT lamp (arc mercury tubular). Its former name is PRK (direct mercury-quartz). The DRT lamp is a cylindrical tube made of quartz, which transmits UV rays. In the end parts of the tube, metal electrodes are soldered for connection to a source of electric current. The air in the tube is removed and replaced with readily ionizable argon. The tube contains a small amount of mercury, which changes into a vapor state when the tube is in operation. An electric current with a voltage of 120 V and a power of 4 A is passed through the tube. In this case, mercury vapor begins to glow (luminesce). Up to 70% of the light flux is UV rays, the rest is the visible area, mainly violet, blue and green zones.

The UV region of radiation is divided into three zones: long-wave (from 400 to 320 nm.), Medium-wave (from 320 to 280 nm), short-wave (from 280 to 180 nm). From the standpoint of practical physiotherapy, it is important to distinguish the zone of long-wave ultraviolet rays (DUV) and the zone of short-wave ultraviolet rays (SUV). DUV and EUV radiation are combined with medium wave radiation, which is not specifically emitted.

Sources of UV radiation are divided into integral and selective. Integrated sources emit the entire UV spectrum, selective to any one zone, short or long wavelength. The radiation spectrum required for therapeutic use is provided by the operating mode of the lamp in sources of integral flux or UV rays, or by a special coating on its inner surface that delays UV rays.

Basic biophysical processes take place electronically. Electrons move from one energy level to another, higher one, having received energy from the UV quantum to overcome the attraction of the nucleus. If the energy of UV radiation is high enough, then the electron is knocked out of the outer orbit. A particle that loses an electron becomes positively charged, while a particle that gains an ejected electron becomes negatively charged. These processes of moving electrons are called the photoelectric effect. As a result of such processes, atoms and molecules are activated, the electrical properties and dispersion of cell colloids change, which affects their vital activity.

The rays also have a photochemical effect, the manifestations of which are the processes of photoisomerization. In molecules, an internal rearrangement of atoms occurs without changing the chemical composition of the substance. In this case, the biological object acquires new chemical and biological properties.

Under the influence of UV rays, the process of photooxidation occurs - an increase in oxidative reactions in tissues.

Basic physiological reactions and therapeutic effect.

There are direct (local) and general effects of UV rays. The general action includes humoral, neuro-reflex and vitamin-forming. Using different dosages and irradiation techniques, one can obtain the predominance of one or another action.

Direct action is manifested in the skin, into which UV rays penetrate no further than 1 mm. They do not have a thermal effect ("cold rays"). EUV rays are absorbed primarily by proteins contained in the cell nucleus, UV rays - by proteins of protoplasm. With sufficiently intense and prolonged exposure, denaturation and coagulation of the protein occurs, as a result of this - necrosis of epidermal cells, aseptic inflammation. The dead protein is cleaved by proteolytic enzymes. At the same time, biologically active substances are formed: histamine, serotonin, acetylcholine and others, the amount of oxidation products, primarily lipid peroxides, increases.

Externally, the local effect is manifested by the formation of UV erythema, the skin becomes slightly swollen and painful, its temperature rises. This erythema is uniform, with clear boundaries, appears after a certain latent period of time: under the action of UV rays after 1.5-2 hours, DUV rays - after 4-6 hours. It reaches its maximum intensity after 16-20 hours, lasts for several days, gradually fading away. The erythema caused by UV rays lasts longer. The most sensitive to UV rays is the skin of the abdomen. Next in terms of the degree of sensitivity reduction are: the skin of the chest and back (about 75% in relation to the sensitivity of the skin of the abdomen), the outer surface of the shoulder (75-50%), the forehead, neck, thigh, calves (50-25%), the back surface of the hands and stop (25%),

With repeated exposure to the same area of ​​the skin, its adaptive reaction to the action of UV rays develops. This is manifested by thickening of the stratum corneum of the skin and the deposition of melanin pigment. Melanin is formed 3-4 days after the onset of erythema. Pigmentation is possible without the preliminary formation of erythema. Melanin protects deeper tissues from overheating by absorbing visible and infrared rays. Melanin itself is unlikely to protect against UV rays, since it is formed in the basal layer of the skin, where they do not penetrate. The pigment is formed under the action of UV rays. The rays of the UV zone have a powerful bactericidal effect, for this purpose they are mainly used.

UV rays stimulate the activity of cellular elements of the skin, which is confirmed by an increase in the number of mitoses. As a result, the processes of epithelialization are accelerated, the formation of connective tissue is activated. In connection with this action, they are used to treat slowly healing wounds and ulcers. The activation of neutrophils and macrophages increases the skin's resistance to infection, which is used to treat and prevent its pustular lesions.

Under the influence of erythemal doses of UV rays, the sensitivity of the nerve receptors of the skin decreases, some of them are destroyed, subsequently recovering. This action is an indication for the use of UV rays for the purpose of pain relief.

The overall humoral effect of UV rays is associated with the absorption and entry into the bloodstream of biologically active substances formed in the skin. Usually this action is considered on the example of histamine, the physiological antagonists of which are catecholamines: epinephrine and norepinephrine. If the amount of histamine and other biologically active substances is so high that the activity of the sympathetic-adrenal system is insufficient to neutralize their action, then general pathological reactions predominate, which is observed when large skin surfaces are irradiated with erythemal doses. In this case, destructive changes in the adrenal glands may occur. Multiple applications of therapeutic doses of UV rays stimulate the sympathetic-adrenal and pituitary-adrenal systems, the function of the adrenal cortex, thyroid and gonads by the humoral mechanism, which ultimately increases their performance. This effect creates the effect of training.

Among the humoral effects, special attention should be paid to the stimulation of the body's immunobiological defenses, the activation of immune responses. There was an increase in the content of immunoglobulins in the blood, complement titer with its initially low value, phagocytic activity of peripheral blood neutrophils. It was found that UV rays have a desensitizing effect.

The general neuro-reflex action of UV rays is associated with irritation of the extensive receptor apparatus of the skin. As a result of regular general exposures, reflex responses are improved, which is expressed in a decrease in the generalization of the reflex response and an increase in local protective reactions. The analgesic effect of UV rays, observed with local irradiation, is associated not only with the effect on skin receptors, but also with the creation of a dominant in the central nervous system. Small doses of general irradiation stimulate skin receptors and reflexively stimulate the activity of the central nervous system. The effect on the endocrine glands is realized not only by the humoral mechanism, but also through reflex effects on the hypothalamus.

Taking into account such a close interaction of humoral and neuro-reflex mechanisms, the theory of the overall action of UV rays is considered as neuro-humoral.

The vitamin-forming effect of UV rays is to stimulate the synthesis of vitamin D. This is due to the physicochemical effect of the DUV zone - the process of photoisomerization. Vitamin D is formed from provitamins found in the fat of the sebaceous glands of the skin: from ergosterol - vitamin D2, from 7-dehydrocholesterol - vitamin D3, from 2,2-dehydroergosterol - vitamin D4. The formation of vitamin D is associated with the influence of UV rays on phosphorus-calcium metabolism, their anti-rachitic effect. The rays of the EUF zone do not have such an effect.

Main indications for use.

a) local exposure:

1. Limited lesions of the skin and mucous membranes for the purpose of bactericidal action, stimulation of healing: infected wounds and ulcers, erysipelas of the skin, irradiation through a tube in diseases of the palatine tonsils, oral mucosa, pharynx, external auditory canal.

2. Diseases of the peripheral nervous system, accompanied by pain, especially in the acute stage.

3. Arthritis (polyarthritis), arthrosis, acute and chronic exacerbations.

4. Inflammatory diseases of internal organs in acute and subacute stages (for example, pelvic organs, bronchi, lungs); impact on the corresponding reflex zones of the skin.

5. For desensitization (for example, with bronchial asthma, fields on the chest).

b) total exposure:

1. Hardening, increasing resistance to infectious diseases.

2. Compensation for natural UV deficiency (work in mines, metro, northern conditions).

3. Rickets in children - treatment and prevention; bone fractures in the rehabilitation stage (in order to mobilize phosphorus-calcium metabolism through the formation of vitamin D).

The main contraindications for use.

1. Hypersensitivity to UV rays (photosensitivity).

2. Generalized dermatitis.

3. Toxic goiter, functional insufficiency of the adrenal glands (in particular, in Addison's disease).

4. Acute and chronic glomerulonephritis.

5. Chronic active and autoimmune hepatitis.

Dosage:

1) by biodose (erythemal or suberythemic);

2) according to the frequency of procedures (with local irradiation in 2-3 days on the same area of ​​the skin, with general irradiation daily);

3) by the number of procedures per course of treatment (with local irradiation 3-4 exposures to the same area of ​​the skin, with total irradiation up to 25).

In physiotherapy, a biological method of dosing UV rays is used, which evaluates the individual reaction of a person. The dose unit is one biological dose (1 biodose).

1 biodose is the minimum exposure time, expressed in minutes, which is sufficient to obtain threshold erythema. Threshold erythema is the weakest (minimal) erythema, but uniform and with clear boundaries.

To determine the biodose, a biodosimeter is used, which is a plate with six rectangular holes. It is fixed on the skin of the abdomen on the left or on the inside of the forearm. The source of UV rays, with the help of which medical procedures will subsequently be carried out, is installed at a distance of 50 cm from the skin surface, the first hole is opened and it is irradiated for 0.5 minutes. Then, with an interval of 0.5 minutes, the remaining five holes are sequentially opened. Therefore, the skin of the first area is irradiated for 3 minutes, the second - 2.5 minutes, the third - 2 minutes, the fourth - 1.5 minutes, the fifth - 1 minute and the sixth - 0.5 minutes. The next day (after 18-20 hours), the intensity of the resulting erythema in different areas of the skin is assessed and a threshold value is selected.

Distinguish between suberythemic doses, that is, not causing skin erythema, and erythemal. The suberythemal dose is a part of the biodose, which is usually denoted as a simple fraction (from 1/8 to 7/8 of the biodose). Among erythemal doses, small or slightly erythemal (1-2 biodoses), medium or erythemal (3-4 biodoses), large or hypererythemic (5-8 biodoses) are distinguished.

General irradiation is usually carried out with suberythemal doses, and local irradiation with erythemal doses. Erythemal doses are used to irradiate a skin area with an area of ​​not more than 800 kV cm or several areas of the same total area during one procedure.

The effectiveness of ultraviolet irradiation depends both on their timely and systematic use, and on the correct dosage. It should be remembered that the wrong dosage can cause great harm to the child. Therefore, dosimetry (dose measurement) and the correct dosage of ultraviolet rays are of particular importance in pediatric practice. Meanwhile, in many children's institutions, irradiation is carried out "by eye" or according to a scheme, without taking into account the intensity of the radiation of the burner and the individual photosensitivity of the child, which is completely unacceptable.

Among the various methods of dosimetry of ultraviolet rays, the method for determining the biological dose according to Gorbachev is the most widely used. This simple and affordable method is based on the property of ultraviolet rays to cause erythema on the skin. It is formed a few hours after irradiation (latent period) and sometimes lasts for several days.

When determining the biological dose according to Gorbachev, the unit of measurement is the exposure time (usually in minutes) required to cause a slight but clearly expressed erythema in a limited area of ​​\u200b\u200bthe skin at a certain distance of the child from the burner (usually 50 cm). This unit, called the biological dose, or biodose for short, expresses the individual sensitivity of a given child's skin to the effects of the ultraviolet rays of a given mercury-quartz lamp.

Our observations have shown that in infants, the intensity of the erythema reaction and the time of its appearance depend on the state of nutrition of the child and the reactivity of his organism. So, in children of normotrophic erythema appears earlier and is much more intense than in children suffering from malnutrition. In children with exudative diathesis or tuberculosis intoxication, a more severe erythema reaction is often observed.

Comparing the data of our observations on children with numerous observations on adults, we can note two characteristic points: firstly, the latent period between ultraviolet irradiation and the appearance of erythema in children is much shorter (in most cases, after 2-3 hours, they can detect pronounced erythema); secondly, the duration of the erythemal reaction in children is also shorter than in adults.

Erythema appears faster and the threshold of erythemal sensitivity decreases in young children, especially up to one year of age. This is due, no doubt, to the anatomical and physiological characteristics of the nervous system, skin and blood vessels in young children.

Based on the characteristics of the formation of ultraviolet erythema in young children, we modified the method for determining the biodose proposed by Gorbachev.

To determine the biodose, you must have a biodosimeter, centimeter, half-minute and minute hours. The biodosimeter is usually made of tinplate, cardboard or oilcloth and has the form of a small plate (7x9 cm). The plate has 4 parallel slots 2 cm long and 0.5 cm wide. The distance between them is 0.5 cm. The holes are closed with a movable shutter. The plate is fixed in a wide oilcloth belt. The biodose is determined after the burner mode is established, which occurs for a mercury-quartz lamp approximately 10 minutes after ignition.

The method for determining the biodose is as follows. Using an oilcloth belt, the biodosimeter is fixed on the child's stomach or back, and the rest of the body is covered with a thick sheet. The burner of a mercury-quartz lamp is installed vertically exactly at a distance of 50 cm above the plate. At first, all openings of the biodosimeter are closed with a damper. Pushing the shutter sequentially with an interval of 0.5-1 minute, one hole after another is opened, with all previous holes remaining open. The skin area corresponding to the first hole is irradiated for 1 minute; the second section of the skin corresponding to the second hole, also for 1 minute, and the 3rd and 4th for half a minute. Thus, according to the above method, the first opening of the biodosimeter was irradiated with ultraviolet rays for 3 minutes. The second hole is 2 minutes, the third hole is 1 minute and the fourth hole is half a minute.

After determining the biodose and before checking its results, it is not recommended to bathe the child.

After 3-6 hours on one or more irradiated skin areas corresponding to the holes of the biodosimeter, stripes of redness (erythema) of varying intensity appear. The weakest in intensity, but clearly expressed erythemal strip and will express the biodose for this child. If the biodose was determined according to the above method, then if the child has 4 erythemal strips, the biodose will be equal to 1/2 minute, with three - 1 minute, with two - 2 minutes, with one - 3 minutes.

Using new powerful burners, it is necessary to determine the biodose from a distance of 100 cm.

Burners that have been in use for a long time do not cause erythema after 3-4 minutes of irradiation of the holes of the biodosimeter. In such cases, the burner must be replaced with a new one.

If one mercury-quartz lamp determines the biodose on a group of children, then the average data obtained can to some extent serve as an indicator of the intensity of the radiation of the burner. Therefore, when the individual determination of biodose in practical work is associated with great difficulties, one can be guided by the average biodose obtained in a group of 15-20 children.

Let us assume that with this definition of biodose it turned out that in most children the biodose is 1 minute. The doctor in his practical work, when dosing ultraviolet rays, will proceed from this intensity of the burner. As you know, the intensity of the burner decreases over time, therefore, after 1.5-2 months, to determine the average biodose, its determination must be repeated on a new group of children.

It is possible to be guided by the average biodose only as a last resort, in general, as a rule, it is desirable to determine the biodose for each child.

The biodose is determined only for a given child and with a given burner. Therefore, the entire course of irradiation should be carried out using exactly the lamp with which the child's biodose was determined.

As we have already indicated above, the biodose is determined by placing the burner at a distance of 50 cm from the child.

A child's total UV exposure usually starts with a new burner.
from a distance of 100 cm, and with an older one - 70 cm. The longer the burner has been in use, the weaker its effect, and therefore the distance has to be reduced accordingly.

Total ultraviolet irradiation begins with a fractional part of the biodose, and then, gradually increasing the dosage.

When prescribing a dose of ultraviolet rays, it must be remembered that the luminous intensity is inversely proportional to the square of the distance of the irradiated surface from the light source. Therefore, if the light intensity at a distance of 50 cm is taken as a unit, then when the burner of a mercury-quartz lamp is removed from the child’s body up to 70 cm, the light intensity will decrease by 2 times, and when removed to 100 cm, by 4 times. Accordingly, the exposure time should be increased: 2 times at a distance of 70 cm and 4 times at a distance of 100 cm.

Example. The biodose was determined at a distance of 50 cm. The child developed 3 erythema. strips, of which the third is the weakest, therefore, one biodose for a given child at a distance of 50 cm is 1 minute, at a distance of 70 cm - 2 minutes, and at a distance of 100 cm - 4 minutes.

Suppose that the doctor considers it necessary to start irradiating the child with 74 biodoses, then at a distance of 50 cm, the exposure will last 15 seconds, at 70 cm - 30 seconds, i.e. 2 times longer, and at 100 cm - 1 minute, i.e. e. 4 times longer.

Calculating the fractional parts of the biodose can be difficult at first. This work is facilitated by the following scheme.

This scheme allows you to quickly find out how long the exposure should be given to the child after establishing the biodose from a distance of 70 and 100 cm.

To use this scheme, it is enough to know the number of erythemal stripes formed in the child.

Technique and methods of ultraviolet irradiation of children. During the session of ultraviolet irradiation, the eyes of children and staff must be protected by dark glass glasses, since conjunctivitis can develop from the action of ultraviolet rays. To protect personnel from harmful long-term exposure to ultraviolet rays, it is advisable to hang a mercury-quartz lamp (around the reflector) with dark dense matter in the form of a skirt).

When irradiating children, the use of glasses causes a number of difficulties; children cry and cannot calm down for a long time. Even worse, they tolerate cloth bandages. Therefore, it is highly advisable to use a special table for ultraviolet irradiation of young children, then there is no need to put glasses on the irradiated child or blindfold him. Such a table allows you to irradiate two children at the same time, which increases the capacity of the physiotherapy room and saves electricity. To isolate one child from another, the table has a low partition.

A special device protects the child's eyes from the action of ultraviolet rays: from a height of 102 cm, a curtain sewn from two layers of oilcloth is lowered on hinges from the crossbar attached to the partition. At the lower end of the curtain is cut a small semi-circle for the child's neck. During irradiation, a napkin, separate for each child, is fastened with buttons to this lower edge of the curtain. Thus, with the curtain down, the entire body of the child, up to the neck, is exposed to radiation. A mother or a nurse sits at the head of the head behind a curtain, and the child calmly accepts the procedure.

Table dimensions: length 100 cm, width 96 cm, height 53 cm, height to the crossbar 102 cm, partition height 27 cm, installation location of the crossbar from the edge of the table 30 cm.

The table is set in relation to the front door so that the oilcloth curtain blocks the radiation of the mercury-quartz lamp from incoming radiation.

In addition to double tables, nurseries and children's homes should also have tables for individual exposure of children.

General ultraviolet irradiation of a naked child is carried out as follows. Having protected the child's eyes, they lay him on a table or couch, and a mercury-quartz lamp is installed as prescribed by the doctor at the right distance so that the entire surface of the child's body is exposed to ultraviolet rays. Then the signal clock is set. In one session, the front and back surfaces of the body are irradiated. In the conditions of children's homes and nurseries, sessions of general ultraviolet irradiation are usually carried out every other day or the first ten sessions daily, and subsequent sessions every other day.

The doctor prescribes the dosage of the rays, the distance of the lamp from the child's body and the duration of the procedure, based on the biodose. He makes his appointments in the individual card of the child. Cabinet nurses are required to strictly adhere to these appointments, each time noting the distance from the lamp, the duration of the procedure and the characteristics of the child's condition in the child's procedure card.

Of great importance for the effectiveness of treatment is the condition of children during procedures; the child should lie still with relaxed muscles. For this, children should be accustomed to the atmosphere of a phototherapy room. It is recommended to have a set of easily disinfecting toys in the office. With the right pedagogical approach and the creation of an appropriate environment, children lie calmly. If the child is still restless, screaming, the session should be stopped.

When carrying out ultraviolet irradiation, the following rules must be observed.

1. The area of ​​the room in which irradiation is carried out must be at least 18-20 m2. The room should be bright and isolated (irradiation in the walk-through room is unacceptable).

2. The air temperature in the room should be 18-20°. In the autumn-winter months, it is necessary to use a solux lamp or an electric reflector simultaneously with a mercury-quartz lamp.

3. After 2-3 hours of continuous burning of a mercury-quartz lamp, the room must be ventilated.

4. Ultraviolet irradiation should be carried out no earlier than one hour after feeding the child.

5. In the absence of a special table, the eyes of the staff and the child must be protected by dark glass glasses. After each child, glasses must be disinfected by wiping with alcohol.

6. After the irradiation session, the child should rest for at least 15-20 minutes. Infants rest lying down, and children over the age of 1 year - sitting, playing at a low table.

With general irradiation with a mercury-quartz lamp, gradually increasing doses are used, and various authors have proposed a number of irradiation schemes: in some schemes, the distance does not change during the entire course of treatment and the dose increase is achieved by increasing the duration of exposure, in other schemes, the dose is increased by simultaneously reducing distance and increased duration of exposure. The latter schemes are practically inconvenient and do not always meet the requirements of a gradual increase in dose. The main disadvantage of most of the regimens given in a number of pediatric guidelines is that the recommended dose in them is indicated in minutes without taking into account individual skin sensitivity to ultraviolet rays and the intensity of different burners. It is known that even new burners, and even more so used ones, differ in the quantity and quality of ultraviolet radiation, and therefore it is necessary to focus on biodose.

We have developed a scheme for general ultraviolet irradiation of children. When drawing up this scheme, the biological dose was taken as a basis, at which the intensity of the source of ultraviolet radiation and the individual photosensitivity of the child's skin are taken into account to some extent.

The dose is gradually increased every two sessions by lengthening the duration of irradiation (in a certain number of minutes) according to the fractional part of the biodose with which irradiation began.

Prolonged inhalation of ozone and nitrogen oxides formed during the burning of a mercury-quartz lamp has a harmful effect on the child's body, and therefore the duration of the session should not exceed 10 minutes for each irradiated body surface, and in total no more than 20 minutes. Having reached this duration, it is necessary to shorten the exposure time by reducing the distance from the burner.

In the nursery and children's homes in the autumn-winter time, all infants are recommended to undergo a course of ultraviolet irradiation.

The course of irradiation consists of 15-25 sessions, which are usually carried out every other day. A second course of ultraviolet irradiation should be carried out at the end of winter, but not earlier than 2-3 months after the end of the previous course.

If a child misses one or two sessions, the dose of the last irradiation is usually repeated. If the break was longer, irradiation begins with half the last dose. In the case of a long break after 15-17 sessions, the course of irradiation ends at this point and a second course of treatment is prescribed 1.5-2 months after the last irradiation session.

With general ultraviolet irradiation of children in the autumn-winter season, a solux lamp is used simultaneously with a mercury-quartz lamp (at least 100-120 cm from the child).

Photorius. For group general ultraviolet irradiation at nurseries and children's homes, it is advisable to arrange a fotarium. For this purpose, you can use a mercury-quartz lamp with a powerful PRK-7 burner or a conventional burner used in PRK-2 mercury-quartz lamps.

A mercury-quartz lamp with a PRK-7 burner is installed in the center of a room with an area of ​​20-25 m2 or suspended from the ceiling at least 2 m from the floor. When using the PRK-2 burner, it is mounted in a vertical position. The burner is removed from the reflector and, by a slight rearrangement, is installed in a vertical position and suspended on a block from the ceiling in the center of the room (the area of ​​​​the room should not be less than 16 m2). This makes it possible to install the burner at different distances from the floor. For infants, as well as for children unable to sit up, for group exposures, the lamp is hung over an arena where children (with protected eyes) are exposed to ultraviolet radiation. Older children, who sit well and independently, receive radiation in a sitting position (in children's chairs). With the help of such a lamp, 10-12 children can be irradiated at the same time. The lamp housing with the power supply is installed in the corner of the room.

The fotarium room should have light-colored walls and ceiling. The floor must be covered with linoleum. The air temperature of the room should be 20-22 °. To create an appropriate thermal regime, 2 solux lamps with 750 or 1000 W burners are placed in the corners of the room. The photorium room should be well ventilated.

According to the location of the lamp, in the center of the room, on the floor, 3 circles are applied with white oil paint: the 1st at a distance of 140 cm, the 2nd at a distance of 100 cm and the 3rd at a distance of 70 cm.

Before carrying out ultraviolet irradiation, the switch on the shield is turned on, and then the lamp switch. If the burner does not ignite, then press the start button several times.

After the lamp is lit, a metal removable cap is put on to protect the persons in the room while the lamp is burning. Personnel working in the photorium must wear dark glasses. To carry out group ultraviolet irradiations, the fotarium must be provided with a sufficient number of dark glasses for children.

Method of ultraviolet irradiation. 8-10 minutes after the ignition of the mercury-quartz lamp, naked children in goggles are placed on chairs in a circle. First, in the first 8 sessions of irradiation, they are placed in the first circle (the most distant), then as the dose of ultraviolet rays increases (from the 9th session) - in the second circle, and the last 6 sessions - in the third circle (closest to center). After the children have sat down, they remove the metal removable cap from the burner and proceed to irradiation. The lamp is lowered to the level of the chest of children, which usually corresponds to 35 cm from the floor for young children. In each session, the front and then the back surface of the body is exposed to radiation, for which the chairs are rotated.

When dosing ultraviolet rays proceed from the average biodose. Biodose is determined on the back or chest. 10-15 children and the average biodose is derived from the data obtained. Ultraviolet irradiation usually begins with 1/4 biodose (on each surface of the body), every 2 sessions increase the time by 1/4 biodose and bring to the end of the course of irradiation up to 2 biodoses. The course of irradiation is 20 sessions. Irradiation is usually performed every other day or the first 10 sessions daily, and the rest every other day.

Phototarii should function throughout the year, but they are especially important in the autumn-winter season.

Contraindications to the use of ultraviolet rays. Ultraviolet irradiation is contraindicated in pulmonary tuberculosis, tuberculosis and inflammation of the kidneys, severe exhaustion, tendency to bleed, decompensated heart disease, and severe anemia. With manifest spasmophilia, ultraviolet irradiation is not recommended. With latent spasmophilia, a course of calcium treatment is first required.

Biodose (biological dose) is a conventional unit by which the minimum duration of ultraviolet irradiation of the skin is determined, which is necessary for the appearance of the weakest (threshold), but clearly defined reddening -.

Biodose is determined by a biodosimeter (Fig. 1) (a metal plate 6 X 10 cm in size with six rectangular holes 0.5x2 cm each, closed by a movable metal shutter).

A biodosimeter sewn to the oilcloth (with closed holes) is applied to the skin of the abdomen or back and secured with ribbons. The part of the body that is not subject to exposure is covered with a sheet. or another source is placed exactly above the biodosimeter at a distance of 50 cm (from the edge of the reflector). Having opened the first hole, irradiation is carried out for one minute, and then all the holes are sequentially opened every minute one after the other. After 6-24 hours, the number of stripes that appeared on the skin and the degree of their redness are taken into account (Fig. 2). In the case of the formation of all 6 strips with a poorly defined 6th of them, the biodose will correspond to 1 minute, with weak erythema on the 5th strip - 2 minutes.

The biodose is determined by the nursing staff when using mercury-quartz irradiators and during sun exposure.

Rice. 2. Determination of biodose on the skin of the abdomen: on the right - biodose 1 min.; left - biodose 2 min.

Biodose (biological dose) is a conventional unit used in phototherapy to denote the amount of ultraviolet radiation energy that causes a threshold (i.e., minimal, but clearly defined) erythemal skin reaction. The value of the biodose is determined by the characteristics of the source of ultraviolet radiation (its intensity, spectral composition and individual sensitivity of the organism to ultraviolet rays).

Individual sensitivity can vary significantly depending on the functional state of the body, in particular in certain diseases; previous ultraviolet irradiation also has a great influence on it. Therefore, in the practice of phototherapy, before starting treatment, the individual biodose under given irradiation conditions should be determined as the initial unit for the dosage of ultraviolet radiation.

The biodose value is expressed by the duration of exposure (in minutes or seconds) required to obtain the specified threshold erythema response. Biodoses are determined by using a mercury-quartz lamp or other sources of intense ultraviolet radiation, less often by sun exposure (see Biodosimeter). Depending on the type of disease, general exposures begin with 1/4-1/2 of the biodose, and to obtain an erythema reaction in a limited area of ​​the skin - with a two-three-fold biodose or even a large dose. See also Ultraviolet rays, Light therapy.