Determination of the patient's biodose. Ultraviolet radiation in medicine, devices, indications, methods

In the 20th century, it was discovered that UV radiation has a generally beneficial effect on humans. Both domestic and foreign researchers have convincingly proven in hundreds of experiments that under the influence of UV radiation, health improves, vigor appears, performance increases, all body functions are activated, blood composition improves, healing of wounds and ulcers is accelerated, and allergic reactions are reduced.

Ultraviolet radiation, although not visible to the eye, is very active in relation to the environment. It is customary to distinguish three areas of ultraviolet radiation, differing in their effects on a living organism:

1) UV-A-..400.320 nm The UV-A spectrum has a relatively weak biological effect. Therapeutic effects: pigment-forming, immunostimulating, photosensitizing.
2) UV-B 320...275 nm The UV-B spectrum has a pronounced biological effect. UV-B rays promote the production of vitamin D, normalize phosphorus-calcium metabolism, increase the mechanical strength of bone tissue, stimulate the restoration of bone tissue during fractures, and increase the resistance of the skin and the body as a whole to harmful environmental factors.
3) UV - C - 275...180 nm The UV-C spectrum has a pronounced bacteriostatic and bactericidal effect on microorganisms located on the skin and mucous membranes.

Narrowband ultraviolet

Narrowband ultraviolet therapy provides a wavelength of 311-312 nanometers, which is intense enough to treat many skin conditions.

The use of narrowband ultraviolet light is considered safe for both adults and children. - Narrowband ultraviolet irradiation is suitable for both light and dark skin. - Ultraviolet rays affect only certain areas of the epidermis, allowing for the most accurate irradiation. - The success rate reaches 0.8 - in fact, this means that 8 out of 10 patients experience a significant improvement in their condition as a result of ultraviolet therapy. - Side effects of ultraviolet therapy - burns or cataract formation - occur as a result of medical error or neglect of necessary precautions. - Narrowband ultraviolet therapy is used in the treatment of common skin diseases such as psoriasis, vitiligo, eczema. - Certain types of dermatitis, prurigo, porphyria, pruritis also require irradiation with narrow-band ultraviolet radiation. - Compared to traditional broadband ultraviolet therapy, this procedure is much more effective.

Narrowband ultraviolet therapy

This procedure is not accompanied by painful sensations, does not require anesthesia or even hospitalization, and the duration of the procedure itself is extremely short: each irradiation session lasts from several seconds to several minutes. The procedure for irradiation with narrow-band ultraviolet light is carried out in regular hospitals, a dermatologist's office, and physical therapy clinics.

The widespread use of narrowband ultraviolet therapy is explained by the simplicity of the procedure and the effectiveness of the results achieved. As a rule, in most cases, narrow-band ultraviolet therapy is combined with other types of treatment, for example, taking medications prescribed by a doctor. The attending physician may recommend ultraviolet therapy if the effect of ointments, creams and other medications is insignificant.

The best results are achieved by following a specific schedule of radiation sessions. Typically, this schedule includes two to five sessions of ultraviolet therapy per week, and the full course of treatment takes 12 weeks. However, depending on a number of factors - including skin type, age, skin condition, area of ​​the body to be irradiated - the duration of the course may vary. Visible results are usually achieved after 5-10 irradiation sessions. On average, the number of sessions ranges from 15 to 25.

There are several methods of ultraviolet therapy. Identify methods photochemotherapy(FHT) and phototherapy. FCT methods include various options for the combined use of long-wave ultraviolet radiation (wavelength 320-400 nm) and psoralens (radiation-enhancing substances). The main ones are FCT with internal or external use of psoralens, as well as PUVA baths (PUVA therapy (PUVA = Psoralen + UltraViolet A) is a therapeutic effect on the skin of long-wave ultraviolet A radiation in combination with Psoralen- a photosensitizer (an agent that increases skin sensitivity to light) of plant origin. Phototherapy methods are based on the use of different wavelengths of ultraviolet radiation without combination with photosensitizing drugs.

The approaches to all existing methods of ultraviolet therapy are largely similar. Before starting treatment, patients should be examined to exclude pathology from internal organs and identify contraindications to phototherapy. For this purpose, a clinical and laboratory examination of patients is carried out, including a general blood test, a general urine test, a biochemical blood test (with a study of liver and kidney function indicators), consultation with a therapist, gynecologist, endocrinologist, and ophthalmologist. According to indications, examination by other specialists is recommended.

For widespread rashes, whole body irradiation is prescribed; in the presence of single lesions, local or local irradiation is performed. For general irradiation, phototherapy cabins with a vertical arrangement of lamps are produced, for local irradiation - devices for local phototherapy of the hands and feet or individual parts of the body (head, torso), as well as devices with fiber-optic light guides that allow radiation to be delivered to any part of the skin.

The initial dose of radiation is prescribed depending on the skin phototype, the degree of tanning and the individual sensitivity of the patient to a particular type of radiation or its combined use with photosensitizers. Based on sensitivity to sunlight, there are 6 skin types (Table No. 1). The first 4 phototypes are determined by anamnestic data (the ability of the patient’s skin to form erythema and tan when exposed to the sun for 30 minutes at the beginning of summer), while phototypes V and VI are determined upon examination of the patient.

Table No. 1.

Determination of individual sensitivity to ultraviolet radiation is carried out according to the standard method by irradiating 6 test fields (2–3 cm in diameter) on the skin of the forearm or buttock with increasing doses. During phototherapy, the individual biodose (minimum erythemal dose - MED) is determined; with FCT, the individual sensitivity of the patient to the combined use of psoralen photosensitizers and long-wave ultraviolet light (minimum phototoxic MED) is determined. The DER or MFD is taken to be the irradiation time required to form minimal erythema with clear contours in one of the test fields. The results of phototesting are assessed after 24 hours for phototherapy, and after 48 or 72 hours for phototherapy.

Determination of biodose

Dosage:

1) by biodose (erythemal or suberythemal);

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

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

UV radiation is dosed using the Gorbachev-Dakfeld biological method. The method is simple and is based on the property of UV rays to cause erythema when irradiating the skin. The unit of measurement in this method is one biodose.

1 biodose is the minimum irradiation time, expressed in minutes, which is sufficient to obtain threshold erythema.

Threshold erythema is the weakest (minimal) erythema, but uniform and with clear boundaries.

Time is measured in seconds or minutes.

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 treatment procedures will subsequently be carried out, is installed at a distance of 50 cm from the surface of the skin, the first hole is opened and it is irradiated for 0.5 minutes. Then, at intervals of 0.5 minutes, the remaining five holes are sequentially opened. Consequently, 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 is selected.

There are suberythemal doses, that is, those that do not cause erythema of the skin, and erythemal doses. The suberythemal dose is part of the biodose, which is usually designated as a simple fraction (from 1/8 to 7/8 of the biodose). Among erythemal doses, small or weakly erythemal (1-2 biodoses), medium or erythemal (3-4 biodoses), large or hypererythemal (5-8 biodoses) are distinguished.

General irradiation is usually carried out with suberythemal doses, and local irradiation with erythemal doses. During one procedure, a skin area with an area of ​​no more than 800 kW cm or several areas of the same total area are irradiated with erythemal doses.

The result of biodosometry is checked after 24 hours. One biodose will be considered the weakest skin hyperemia. With a change in the distance from the emitted surface to obtain the same biodose, the irradiation time changes in inverse proportion to the square of the distance. For example, if the time to receive one biodose from a distance of 20 cm is 2 minutes, then from a distance of 40 cm it will take 8 minutes. The irradiation time can be selected discretely from 30 seconds. up to 60 seconds, and the distance from the body (its skin) to the emitter is from 10 cm to 50 cm. It all depends on the type of skin, but you need to choose these parameters in such a way as to get a clear picture of skin erythema.

Indications for UV irradiation
General UFO is used for:

· increasing the body's resistance to various infections, including influenza and other acute respiratory viral infections

· prevention and treatment of rickets in children, pregnant and lactating women;

· treatment of pyoderma (purulent lesion skin), common pustular diseases of the skin and subcutaneous tissue;

· normalization of the immune status in chronic sluggish inflammatory processes;

· improvement of reparative processes for bone fractures;

· for hardening purposes;

· compensation for ultraviolet (solar) deficiency.

Contraindications to ultraviolet therapy are:

Ultraviolet radiation intolerance

Current or past presence of melanoma and other

malignant skin tumors,

Precancerous skin lesions

Xeroderma pigmentosum,

Systemic lupus erythematosus,

Severe sun damage

Age less than 7 years,

Conditions and diseases for which methods are contraindicated

physiotherapy.

Contraindications to photochemotherapy, in addition to those mentioned above, are intolerance to psoralen photosensitizers, pregnancy, breastfeeding, cataracts or absence of a lens, previous treatment with arsenic preparations and ionizing radiation, severe liver and kidney dysfunction.

Some private methods of ultraviolet therapy

Infectious and allergic diseases. Application of ultraviolet radiation to the skin of the chest using a perforated oilcloth localizer (PCL). The PCL determines the area to be irradiated (prescribed by the attending physician). Dose - 1-3 biodoses. Irradiation every other day, 5-6 procedures.

Hidradenitis axillary(in combination with SMV, UHF, infrared, laser and magnetotherapy). In the infiltration stage, ultraviolet irradiation of the axillary area every other day. Radiation dose - 1-2-3 biodoses successively. Treatment course: 3 irradiations.

Purulent wounds. Irradiation is carried out with a dose of 4-8 biodoses in order to create conditions for the best rejection of disintegrated tissues. In the second phase - in order to stimulate epithelization - irradiation is carried out in small suberythemal (i.e., not causing erythema) doses. The irradiation is repeated after 3-5 days. UV irradiation is carried out after primary surgical treatment. Dose - 0.5-2 biodoses, course of treatment 5-6 irradiations.

Clean wounds. Irradiation is used in 2-3 biodoses, and the surface of undamaged skin surrounding the wound is also irradiated at a distance of 3-5 cm. Irradiation is repeated after 2-3 days.

Boils, hidradenitis, phlegmon and mastitis. UFO begins with a suberythemal dose and quickly increases to 5 biodoses. Radiation dose - 2-3 biodoses. The procedures are carried out after 2-3 days. The lesion is protected from healthy areas of the skin using a sheet or towel.

Furuncle of the nose. UV exposure of the nasal vestibule through a tube. Dose - 2-3 biodoses every other day. The course of treatment is 5 procedures.

Eczema. UFO is prescribed according to the basic scheme daily. The course of treatment is 18-20 procedures.

Psoriasis. Ural irradiation is prescribed as RUVA therapy (photochemotherapy). Long-wave UV irradiation is performed in combination with a photosensitizer (puvalene, aminefurin) taken by the patient 2 hours before irradiation at a dose of 0.6 mg per kilogram of body weight. The dose of radiation is prescribed depending on the sensitivity of the patient’s skin to UV rays. On average, ultraviolet radiation begins with a dose of 2-3 J/cm2 and is increased to 15 J/cm2 by the end of the course of treatment. Irradiation is carried out for 2 consecutive days with a rest day. The course of treatment is 20 procedures.

Ultraviolet radiation with a mid-wave spectrum (SUV) starts with 1/2 according to an accelerated scheme. The course of treatment is 20-25 irradiations.

27.Cryotherapy with liquid nitrogen and carbonic acid snow

Cryotherapy- This treatment cold. Kryo (Greek kryos cold, frost) is a component of compound words that relate to cold.According to modern ideas cryotherapy is a physiotherapeutic procedure, the therapeutic effect of which is based on responses body on hypothermia of the outer (receptor) layer of the skin to a temperature of −2°C. Such subterminal hypothermia does not lead to tissue damage, but has a powerful irritating effect on the central nervous system, which causes a number of positive changes in the immune, endocrine, circulatory and other systems of the body.

The cryotherapy method is widely used in the treatment of various skin diseases and cosmetic imperfections. Cold acts on the nerve endings of the skin and reflexively on the autonomic nervous system. Under its influence, biochemical processes change not only in cells that are directly exposed, but also in deeper tissues. As a result, skin nutrition improves.

It is necessary to distinguish between general and local cryotherapy, which, despite the similarity of physical effects, give fundamentally different results. General cryotherapy (OCT) stimulates the entire receptor field of the skin and affects the central nervous system. Local cryotherapy produces local effects that can be achieved using cheaper coolants.

General cryotherapy: the patient enters a special room filled with chilled gas. Depending on the volume of the room, it moves (in cryo-simulators) or stands still (in cryocabins, cryo-pools). Devices for general cryotherapy are also popularly called “cryosaunas”.

Local cryotherapy: part of the patient’s body is covered with cooling elements or blown with a stream of cooled air.

The effectiveness of the procedure depends on the dynamics of heat removal and the duration of cooling. The duration of the procedure is selected individually, depending on constitution patient and the number of procedures already completed. In the practice of dermatologists and cosmetologists, carbonic acid snow and liquid nitrogen are used for local cryotherapy.

Treatment with carbonic acid snow .

Depending on pressure and exposure, carbon dioxide snow causes destructive changes in the skin, expressed to varying degrees. Obliteration of small vessels occurs, preventing blood flow to the lesion, the permeability of the vessel walls increases, the exudation of plasma and blood cells increases, facilitating the evacuation of decay products and the resorption of pathological elements. Cryotherapy has antipyretic, anti-inflammatory, antipruritic and analgesic effects.

Cryomassage with carbonic acid snow.

Used for oily seborrhea, acne vulgaris and rosacea, sagging skin. It is carried out with minimal pressure and a short-term effect on the vessels and glands of the skin, the neuroreceptor apparatus, and facial muscles, which helps to reduce the redness of the skin with rosacea, resolve inflammatory infiltrates with vulgar acne, increase muscle tone with sagging skin and reduce the function of sebum secretion with oily skin. skin.

Carbon dioxide in a liquid state is stored in a cylinder. A bag made of thick fabric is put on the valve and slowly, by opening and closing the tap, carbon dioxide is released, which turns into snow with a temperature of - 78 ° C. Before the procedure, the skin is treated with 70% ethyl alcohol. A dense lump of snow is wrapped in several layers of gauze; Only the working surface remains open, with which the skin is massaged. The massage is performed with small stroking movements, in the direction of the skin lines, it is necessary to avoid displacement of the skin; the massage should be done very superficially, quickly and deftly. Don't stop and press on the skin.
The cryomassage procedure is short-term: from 30 seconds. at the beginning of the course to 2 - 3 minutes at the end of treatment. The massage session ends with the application of a nourishing mask or cream. After 3 – 5 minutes. after completion, the redness of the skin intensifies and then gives way to a matte tint. For 2-3 hours, the feeling of pleasant heat in the skin, a feeling of refreshment, and tightness and elasticity continues. Cryomassage is prescribed 1 to 3 times a week; There are 15-20 procedures per course. When treating aging skin, use carbonic acid instead of snow

Treatment with liquid nitrogen.

Liquid nitrogen has the most “successful” properties for cryotherapy: it has a low temperature, is non-toxic, non-explosive, chemically inert, and non-flammable. Stored and transported in special Dewar vessels (James Dewar, cavernous hemangiomas, chronic eczema, boils at the beginning of infiltration, diffuse and alopecia alopecia, common, flat and plantar warts, genital warts, molluscum contagiosum, senile keratomas, fibromas, pyogenic granuloma, lichen planus, sebaceous gland adenoma, keloids, basal cell carcinoma, hyperkera toz , spherical, pink, keloid and common acne, focal neurodermatitis, loose skin, wrinkles.

Liquid nitrogen has high therapeutic activity. The therapeutic effect is based on its low temperature. Depending on the exposure, liquid nitrogen has a different effect on tissue: in some cases it causes destruction and death of tissue, in others it causes only a short-term narrowing of blood vessels.

Methods of liquid nitrogen therapy for various diseases.

Adenoma of the sebaceous glands. Freezing deep. The applicator is placed perpendicular to the surface of the skin, each element is frozen separately.

Alopecia orbicularis. Massage with liquid nitrogen is carried out with a wide applicator until a slight, quickly passing blanching appears.

Warts are flat. Apply skin shading. The applicator is placed parallel to the skin surface and moved over the treated area with rotational movements.

Plantar warts. Previously, hyperkeratotic layers are removed as much as possible using keratolytic agents and mechanical treatment with pedicure instruments after steaming the skin of the feet. The technique for performing the procedure is the same as for vulgar warts.

Warts are simple. The applicator is placed perpendicular to the wart, each element is processed separately with an exposure time of up to 35 s. As the liquid nitrogen evaporates, the applicator is re-wetted with liquid nitrogen and the procedure is repeated. Subjectively, the patient experiences a burning sensation, tingling, pain. The goal of treatment is tissue destruction. Approximately 1 minute after freezing, hyperemia and swelling of the wart appear, and a day later an epidermal blister appears. Large bubbles are opened at the base with scissors and treated with brilliant green. If there is no therapeutic effect, the procedure is repeated.

Keloid scars. Freezing deep. The exposure is increased to 2 minutes, so bubbles always form. In one session, 3 cauterizations can be performed, for a course of 5-7 procedures.

Acne rosacea e. Freezing is carried out using an applicator. A wooden stick 30-40 cm long can be used as an applicator, at the end of which a cotton swab is fixed. Before the procedure, the lesions are wiped with 70% alcohol. The applicator is moistened with liquid nitrogen and the areas are treated with a continuous rotational movement, pressing lightly, until a quickly disappearing whitening of the skin appears.
Similar treatment is carried out for pyogenic granuloma.

When treating other skin lesions ( seborrhea, acne, rosacea, sagging skin, sallow complexion) use liquid nitrogen massage. Cryomassage is technically convenient and provides a quick therapeutic effect.

Cryomassage is carried out on dry, fat-free skin, so the skin is wiped before the procedure 70% ethyl alcohol

To perform cryomassage, you can use a special device - a nitrogen sprayer - or an applicator and a thermos with liquid nitrogen.

To prepare the applicator, you need to take a wooden stick approximately 15-20 cm long, wrap cotton wool very tightly around it, and then shake it several times to make sure it is strong. Then open the thermos with nitrogen, lower the applicator there for a few seconds, then shake off the excess nitrogen and begin the procedure. Continuous rotational movements are made along the massage lines with the applicator with light pressure until the whitening of the skin quickly disappears. The patient should feel a slight tingling and burning sensation that does not cause discomfort. The procedure is carried out until slight hyperemia appears, approximately 5-7 minutes.

The course of treatment can be 10-15 procedures, which are done every 1-2 days or every day.

For various forms of baldness, the course of treatment can be supplemented with cryomassage of the scalp. Comb hair parallel to combed partings using an applicator with liquid nitrogen carry out rapid rotational movements.

The duration of the procedure is 5-7 minutes, the course of treatment is 10-15 procedures every other day.

The effectiveness of ultraviolet irradiation depends both on its 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 burner radiation and the child’s individual photosensitivity, which is completely unacceptable.

Among the various methods of dosimetry of ultraviolet rays, the most widely used is the method of determining the biological dose according to Gorbachev. This simple and accessible method is based on the property of ultraviolet rays to cause erythema on the skin. It forms several 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 irradiation time (usually in minutes) required to cause a weak but clearly defined erythema in a limited area of ​​the 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 the skin of a given child to the effects of 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 child’s nutritional status and the reactivity of his body. Thus, in normotrophic children, 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 from our observations of children with numerous observations of 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 it is possible to detect pronounced erythema); secondly, the duration of the erythema reaction in children is also shorter than in adults.

Erythema appears faster and the threshold of erythema sensitivity decreases in young children, especially up to one year of age. This is explained, without a doubt, by 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 clock. The biodosimeter is usually made of tinplate, cardboard or oilcloth and has the shape 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 flap. The plate is secured 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 secured 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. Initially, all holes of the biodosimeter are closed with a shutter. By extending the damper sequentially at intervals of 0.5-1 minutes, one hole after another is opened, with all previous holes remaining open. The area of ​​skin corresponding to the first hole is irradiated for 1 minute; the second area of ​​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 hole of the biodosimeter was irradiated with ultraviolet rays for 3 minutes. The second hole is 2 minutes, the third 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, stripes of redness (erythema) of varying intensity appear on one or more irradiated areas of the skin corresponding to the holes of the biodosimeter. The weakest in intensity, but clearly defined erythema stripe will express the biodose for a given child. If the biodose was determined according to the above method, then if the child has 4 erythema stripes, 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 biodosimeter holes. In such cases, the burner should be replaced with a new one.

If the biodose is determined on a group of children using one mercury-quartz lamp, then the average data obtained can to some extent serve as an indicator of the intensity of the burner radiation. Therefore, when individual determination of the 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 the biodose, it turned out that for most children the biodose is equal to 1 minute. In his practical work, the doctor will proceed from this burner intensity when dosing ultraviolet rays. As is known, 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.

You can only rely on the average biodose as a last resort; in general, as a rule, it is advisable 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 the exact 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.

General ultraviolet irradiation of a child is usually started with a new burner
from a distance of 100 cm, and with an older one - 70 cm. The longer the burner was in use, the weaker its effect, and therefore the distance has to be reduced accordingly.

General ultraviolet irradiation begins with a fraction of the biodose, and then gradually increases the dosage.

When prescribing a dose of ultraviolet rays, it must be remembered that the light 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 unity, 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 up to 100 cm - by 4 times. Accordingly, the irradiation 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 equal to 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 a child with 74 biodoses, then at a distance of 50 cm the irradiation will last 15 seconds, at 70 cm - 30 seconds, i.e. 2 times longer, and at 100 cm 1 minute, i.e. i.e. 4 times longer.

Calculating fractional parts of a biodose can be difficult at first. This work is made easier by using the following diagram.

This scheme allows you to quickly navigate the duration of irradiation that should be given to a child after establishing a biodose from a distance of 70 and 100 cm.

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

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

When children are exposed to radiation, the use of glasses causes a number of difficulties; children cry and cannot calm down for a long time. They tolerate cloth bandages even worse. Therefore, it is very 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 two children to be irradiated at the same time, which increases the throughput of the physiotherapy room and saves energy. To isolate one child from another, the table has a low partition.

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

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

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

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, place him on a table or couch, and install a mercury-quartz lamp as prescribed by the doctor at the required distance so that the entire surface of the child’s body is exposed to ultraviolet rays. Then the alarm clock is installed. The front and back surfaces of the body are irradiated in one session. In orphanages 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 rays, the distance of the lamp from the child’s body and the duration of the procedure based on the biodose. He enters his appointments into the child’s individual card. The office nurses are required to strictly adhere to these appointments, each time noting in the child’s procedure card the distance from the lamp, the duration of the procedure and the characteristics of the child’s condition.

The condition of children during procedures is of great importance for the effectiveness of treatment; The child should lie quietly with relaxed muscles. To do this, children should be accustomed to the environment of a light therapy room. It is recommended to have a set of easily disinfectable toys in your office. With the right pedagogical approach and the creation of an appropriate environment, children lie calmly. If the child is still restless and screams, 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 (exposures in a walk-through room are unacceptable).

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

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

4. Ultraviolet irradiation should be carried out no earlier than an hour after feeding the baby.

5. In the absence of a special table, the eyes of the staff and the child must be protected with 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 1 year of age rest sitting, playing at a low table.

During 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 throughout the entire course of treatment and an increase in dose is achieved by increasing the duration of irradiation; in other schemes, the dose increases due to a simultaneous decrease distance and increasing the duration of irradiation. The latter regimens 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 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, vary in the quantity and quality of ultraviolet radiation, and therefore it is necessary to focus on the biodose.

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

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 combustion 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, you should shorten the irradiation time by reducing the distance from the burner.

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

The course of radiation consists of 15-25 sessions, which are usually carried out every other day. A repeated 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 last dose of radiation is usually repeated. If the break was longer, irradiation begins with half the last dose. In case of a long break after 15-17 sessions, the course of irradiation is completed at this point and a second course of treatment is prescribed 1.5-2 months after the last irradiation session.

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

Fotary. For group general ultraviolet irradiation at nurseries and children's homes, it is advisable to arrange a photaria. 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, through 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 who are unable to sit, for group irradiation, the lamp is suspended above the playpen, where the children (with their eyes protected) are exposed to ultraviolet irradiation. Older children who sit well and independently receive radiation in a sitting position (on children's chairs). Using such a lamp, 10-12 children can be irradiated simultaneously. The lamp body with the power supply is installed in the corner of the room.

The fotaria room should have lightly painted walls and ceiling. The floor should be covered with linoleum. The room air temperature should be 20-22°. To create an appropriate thermal regime, 2 Sollux lamps with 750 or 1000 W burners are placed in the corners of the room. The fotarium room must 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 panel is turned on, and then the lamp switch. If the burner does not light, press the start button several times.

After the lamp is lit, a removable metal cap is put on to protect those in the room while the lamp burns. Personnel working in the fotaria must wear dark glasses. To carry out group ultraviolet irradiation, the photaria must be provided with a sufficient number of dark glasses for children.

Ultraviolet irradiation technique. 8-10 minutes after lighting the mercury-quartz lamp, naked children wearing safety glasses are placed on chairs in a circle. First, in the first 8 irradiation sessions, 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 are seated, remove the removable metal cap from the burner and begin irradiation. The lamp is lowered to the level of the children's chest, 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 irradiated, for which the chairs are turned.

When dosing ultraviolet rays, the average biodose is used. The 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 (for each surface of the body), after every 2 sessions the time is increased by 1/4 biodose and is brought to 2 biodoses by the end of the irradiation course. 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.

Fotaria 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 for pulmonary tuberculosis, tuberculosis and inflammation of the kidneys, severe exhaustion, tendency to bleeding, decompensated heart defects, as well as severe anemia. In case of manifest spasmophilia, ultraviolet irradiation is not recommended. For latent spasmophilia, a course of calcium treatment is first required.

Phototherapy- a method of physiotherapy, which consists of dosed exposure to infrared, visible, and ultraviolet radiation on the patient’s body.

Ultraviolet radiation in the optical wavelength range occupies a region from 100 to 380 nm, which is divided into three regions: C = short wavelength (100-280 nm), B - medium wavelength (280-315 nm), A - long wavelength (315-380 nm) . In physiotherapy, UV radiation with a wavelength of 235-380 nm is used for therapeutic and preventive circuits. This radiation penetrates the surface layers of tissue to a depth of 0.1-1 mm. When absorbed by the skin, UV rays lead to photochemical and photobiological reactions.

Dosimetry and dosing of ultraviolet radiation

Currently, domestic compact portable devices (UV radiometers) are produced for practice, making it possible to measure the energy characteristics of any sources of UV radiation with high accuracy. In the practical work of health care and sanatorium-resort institutions, the following can be used:

1. UV radiometer "Ermeter", 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 area 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 “Bactmeter”, designed to measure bactericidal UV illumination from bactericidal lamps.

All of the above radiometers consist of an electronic unit with a digital output and a photoreceiving head, the spectral sensitivity of which in different types of radiometers is adjusted to the tabulated sensitivity in accordance with WHO recommendations. Using 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 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 irradiation or radiation intensity, but also take into account the nature of the biological effect it causes. In this regard, the method (Dalfeld-Gorbachev) of assessing individual photosensitivity of the skin to UV rays has become widespread in practice (Fig. 327). With this method, the minimum duration of irradiation time required to obtain a threshold erythema reaction of the skin is determined. One biological dose (biodose) is taken as a unit of measurement.

The 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;

the biodose from irradiators of the “ON” or “BOP-4” type (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 shutter moving on top. The biodosimeter is sewn into oilcloth and has ribbons for fixing it on the patient’s body.

Determination of biodose

1. The patient’s position on the couch is lying on his back. The patient puts on sunglasses.

2. A biodosimeter with closed windows is attached to the skin of the abdomen outward from the midline (right or left). Areas of the body not subject to UV irradiation are covered with a sheet.

3. The irradiator lamp is placed above the biodosimeter, measuring along a plumb line with a centimeter tape the distance required for subsequent treatment procedures (30 or 50 cm) from the radiation source to the surface of the biodosimeter.

4. Turn on the irradiator and sequentially (opening the shutter every 30 s) irradiate 1-6 windows of the biodosimeter.

5. Upon completion of irradiation of all windows, close them with a shutter and turn off the irradiator.

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

17. Ultraviolet irradiation according to the general method. Indications. Contraindications. Characteristics of the therapeutic effect of ultraviolet irradiation. Dosing.

Penetrates tissue up to 1 mm. With general irradiation, during one procedure, the front and back surfaces of the patient’s naked body are exposed alternately. Irradiation can be individual or group. The patient's position is lying or standing.

1. Long-wave ultraviolet irradiation. Wavelength from 320-400 nM. stimulates the formation of melanin in cells.

Therapeutic effect: pigment-forming, immunostimulating.

indications: joint pain, over-drowning, skin pain, slow-healing wounds, ulcers.

contraindications: acute inflammatory purulent diseases, impaired liver and kidney function, hyperstenosis.

Equipment: fluorescent lamps.

Dosing is carried out according to the intensity and duration of irradiation

2. Medium wave ultraviolet irradiation. Wavelength 280-310 nM.

Promotes the formation of vitamin D, stimulates reparative processes, enhances epithelization, and has a pigment-forming effect.

therapeutic effects: -suberythemal doses have a vitamin-forming and immunomodulatory effect; - erymic doses have an analgesic effect.

indications: acute inflammation of internal organs, post-mortem injuries of the musculoskeletal system, inflammation of the peripheral nervous system.

contraindications: hyperstenosis, chronic renal failure.

Biodose: - minimum irradiation time from a certain distance to obtain a weak, but clearly defined erythema.

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

The UV radiation region 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 (SWUV). DUV and AF radiation are combined with medium wave radiation, which is not specially distinguished.

UV radiation sources are divided into integral and selective. Integral sources emit the entire UV spectrum, selective for 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 AF rays, or by a special coating of its inner surface that blocks AF rays.

Basic biophysical processes occur at the electronic level. Electrons move from one energy level to another, higher one, receiving 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 has lost an electron becomes positively charged, and a particle that has gained a knocked-out electron becomes negatively charged. These processes of electron movement 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 functions.

The rays also have a photochemical effect, the manifestations of which are photoisomerization processes. In molecules, 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 effects.

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

The immediate effect is manifested in the skin, deep into which UV rays penetrate no further than 1 mm. They do not have a thermal effect (“cold rays”). KUV rays are absorbed primarily by proteins contained in the cell nucleus, while DUV rays are absorbed by protoplasmic proteins. With sufficiently intense and prolonged exposure, denaturation and coagulation of the protein occurs, which results in necrosis of epidermal cells and aseptic inflammation. The dead protein is broken down by proteolytic enzymes. In this case, biologically active substances are formed: histamine, serotonin, acetylcholine and others, and 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, and its temperature rises. This erythema is uniform, with clear boundaries, appears after a certain latent period of time: under the influence of EF 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. Erythema caused by DUV rays lasts longer. The skin of the abdomen is most sensitive to UV rays. 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%), forehead, neck, thighs, calves (50-25%), the back of the hands and stop (25%),

With repeated exposure to the same area of ​​the skin, an adaptive reaction to the action of UV rays develops. This is manifested by thickening of the stratum corneum of the skin and deposition of the melanin pigment. Melanin is formed 3-4 days after the onset of erythema. Pigmentation is possible without the prior 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 influence of DUV rays. The rays of the KUV zone have a powerful bactericidal effect, and 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, epithelization processes are accelerated and the formation of connective tissue is activated. Due to this effect, they are used to treat slow-healing wounds and ulcers. Activation of neutrophils and macrophages increases the skin's resistance to infection, which is used for the treatment and prevention of 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 restored. This action is an indication for the use of UV rays for pain relief.

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

Among the humoral effects, stimulation of the body’s immunobiological defense and activation of immune reactions deserve special attention. There was an increase in the content of immunoglobulins in the blood, complement titer with an initially low value, and phagocytic activity of peripheral blood neutrophils. It has been found that UV rays have a desensitizing effect.

The general neuro-reflex effect of UV rays is associated with irritation of the extensive receptor apparatus of the skin. As a result of regular general irradiation, 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 anti-pain 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 effect 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 through the humoral mechanism, but also through reflex effects on the hypothalamus.

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

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 and their antirachitic effect. The rays of the KUV zone do not have such an effect.

Main indications for use.

a) local irradiation:

1. Limited damage to 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 for 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 exacerbation of chronic.

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

5. For desensitization (for example, in case of bronchial asthma, fields on the chest).

b) general 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).

Main contraindications for use.

1. Increased sensitivity to UV rays (photosensitization).

2. Generalized dermatitis.

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

4. Acute and chronic glomerulonephritis.

5. Chronic active and autoimmune hepatitis.

Dosage:

1) by biodose (erythemal or suberythemal);

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

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

Physiotherapy uses a biological method of dosing UV rays to evaluate a person's individual response. The dose unit is one biological dose (1 biodose).

1 biodose is the minimum irradiation 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 treatment procedures will subsequently be carried out, is installed at a distance of 50 cm from the surface of the skin, the first hole is opened and it is irradiated for 0.5 minutes. Then, at intervals of 0.5 minutes, the remaining five holes are sequentially opened. Consequently, 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 is selected.

There are suberythemal doses, that is, those that do not cause erythema of the skin, and erythemal doses. The suberythemal dose is part of the biodose, which is usually designated as a simple fraction (from 1/8 to 7/8 of the biodose). Among erythemal doses, small or weakly erythemal (1-2 biodoses), medium or erythemal (3-4 biodoses), large or hypererythemal (5-8 biodoses) are distinguished.

General irradiation is usually carried out with suberythemal doses, and local irradiation with erythemal doses. During one procedure, a skin area with an area of ​​no more than 800 kW cm or several areas of the same total area are irradiated with erythemal doses.

Does not cause a feeling of warmth during irradiation. 11/2-2 hours after irradiation, a slight redness appears on the irradiated area of ​​the skin, which can become very intense 6-7 hours after irradiation. The degree of redness of the skin depends not only on the intensity of radiation, but also on the sensitivity of the skin of the irradiated person.

The need for dosage of ultraviolet irradiation

As physical conditions change, the radiation intensity of a mercury-quartz lamp also changes. For example, its mode, and therefore the intensity of radiation, is affected by voltage fluctuations in the city network and in the operation of the transformer. In addition, the skin's reaction to ultraviolet radiation varies not only among different individuals, but also among the same person, depending on a number of conditions (season, disease, location of irradiation, etc.).
In order to systematically monitor the mode of mercury-quartz lamps (voltage and current), you should use a voltmeter and ammeter. If there are voltage fluctuations in the network, it is advisable to use a voltage stabilizer.

The new lamp has maximum photochemical effect. During the first months of operation of the lamp, the intensity of its radiation begins to gradually decrease, especially in its ultraviolet part.

In order for ultraviolet radiation to have an effective effect on the human body, its correct dosage is necessary, since too intense radiation (overdose) can cause a number of complications (burns, exacerbation of the disease process, etc.). We still do not have an accurate and easily accessible method for measuring radiation intensity. Many of the proposed methods are not accurate and therefore are not widely used.

The most accessible and practical value is the widely used biological dosage method, based on the property of ultraviolet radiation to cause redness of the irradiated skin (erythema).

For each patient, the minimum dose of ultraviolet radiation that causes mild, uniform and clear erythema on the skin (threshold erythema) is determined; this dose is called the biological dose (abbreviated biodose). In this case, however, it is not the dose of ultraviolet radiation that causes threshold erythema that is determined, but the duration of irradiation in minutes at which the appearance of threshold erythema .

Using a biodosimeter to correctly determine the radiation dose

For this purpose, the so-called biodosimeter , which is a metal plate (Fig. 64) measuring 10x6 cm with 6 rectangular, parallel holes measuring 2x0.5 cm each. A metal flap moves freely along these holes. The dosimeter is sewn into oilcloth and equipped with a band for fixing it on the patient’s body.

Rice. 64. Biodosimeter.

For small children, a biodosimeter is proposed in the form of a circle with a diameter of 7-8 cm with 6 radially located holes.

The biodosimeter is usually fixed in the lower abdomen outward from the navel; while the rest of the body surface is covered with a sheet. The patient's face can also be protected with a special screen. The lamp is installed so that the irradiated area is strictly below it and the radiation falls perpendicularly to the irradiated field.

When determining the biodose, the lamp is usually installed at a distance of 50 cm from the irradiated area (this distance is measured with a wooden square or a tape attached to the handle of the reflector of the irradiator). 10 minutes after the lamp begins to glow, irradiation can begin. First, the first hole of the plate is opened and the area of ​​skin under it is usually irradiated for one minute, then the second hole is opened and the area of ​​skin under it is also irradiated for one minute. Subsequently, one after the other, the remaining 4 holes are opened sequentially at intervals of one minute, irradiating the skin in the area of ​​each hole for the same time. Thus, after 6 minutes, when the last (sixth) hole is opened, the skin in the first area will be irradiated for 6, in the second - 5, in the third - 4, in the fourth - 3, in the fifth - 2 and in the sixth - 1 min. After irradiation, the biodosimeter is closed, the irradiator is moved to the side, the biodosimeter is removed from the patient and the patient is released. Usually the next day (24 hours later), the duration of irradiation to obtain a biodose is determined based on the severity of erythema. So, if the weakest, but clearly expressed erythema in the four corners of the strip is on the fourth strip (counting from the most pronounced), then the biodose is obtained in 3 minutes, with the weakest erythema on the fifth strip it is obtained in 2 minutes, etc. This biodose corresponds only to a given patient, with a given lamp and a given distance. The patient should then be irradiated with the same lamp that was used to determine the biodose.

If erythema was not obtained in any area, the biodose is determined again on a symmetrical area of ​​the abdominal skin, as indicated; after that, leaving all the holes of the biodosimeter open, they are additionally irradiated for 6 minutes, as a result of which the least irradiation of the skin (at the last hole) will last 7 minutes, the longest (at the first hole) - 12 minutes. Dose and with less scattering of the lamp from the irradiated surface, starting with irradiation of one minute.

If all 6 stripes are visible, which is observed with increased sensitivity of the skin to ultraviolet radiation, the biodose is determined again on a symmetrical area of ​​the abdominal skin in the same way as above, but irradiation begins with 1 minute.

Method of general ultraviolet irradiation

Irradiation of the entire body with ultraviolet radiation (the so-called general irradiation) begins with fractional parts of the biodose. Since for general irradiation it is necessary to raise the lamp higher, i.e., to increase the distance between the irradiated surface and the lamp, the duration of irradiation should be increased accordingly. It is determined based on the law that the intensity of light is inversely proportional to the square of the distance. So, for example, when the distance increases by 2 times, the light intensity decreases by 4 times; therefore, the biodose will be obtained over a longer period of time.

To determine the duration of irradiation when changing the distance of the lamp from the body, you can use the table. 2. It indicates the coefficient by which the established duration of irradiation should be multiplied when the distance changes. So, for example, if to obtain a certain dose (or biodose) from a distance of 50 cm one irradiated for 2 minutes, then to obtain the same dose (when irradiated with the same lamp) from a distance of 70 cm one would have to irradiate for almost 4 minutes (2 minX 1.96 = 3.92 min).

Example. The doctor prescribed general radiation, starting with a biodose. When determined from a distance of 50 cm, it was obtained in 3 minutes. General irradiation begins from a distance of 100 cm. The biodose at the new distance will be equal to 3 minutes X 4, i.e. 12 minutes, and therefore irradiation should begin with 3 minutes at a distance of 100 cm. Usually the dose for each two subsequent irradiations is increased by biodoses.

The front and back surfaces of the body are irradiated with the dose specified by the doctor.

For general irradiation, the patient is placed on a couch and the lamp is installed along a plumb line above the abdomen.

Sometimes (with chilliness, etc.), more often in children's practice, to create comfortable conditions, they are simultaneously irradiated with ultraviolet and light-thermal irradiators. As a rule, general irradiation is carried out every other day; 15-20 irradiations are prescribed per course of treatment.

With general irradiation, there should be no redness of the skin throughout the entire course of treatment; if it appears, it means the dosage was incorrect, and irradiation should be stopped until the redness disappears.

The radiation course plan varies. You can either gradually increase the duration of irradiation without changing the distance of the lamp from the patient’s body, or reduce its distance from the patient’s body, or change both the duration of irradiation and the distance of the lamp from the patient’s body. Depending on the patient’s condition, the doctor prescribes one or another treatment plan.

In practical work, it is necessary to change the duration of irradiation and the distance of the lamp from the patient’s body. In this case, you can use example diagrams.

A slow regimen, i.e. a slower progressive increase in dose, is used in children, as well as in weakened individuals during the recovery period, with secondary anemia.

The accelerated scheme can be used when intense radiation is prescribed (for furunculosis, some forms of metabolic disorders, etc.).

For general exposures, determination of the biodose is mandatory. A repeated course of general irradiation can be carried out after a break of 2-3 months. Before a second course of irradiation, the biodose is again determined.

Sometimes it is necessary to urgently begin irradiation and it is not possible to determine the individual biodose for the patient. Then they are guided by the so-called average biodose for a given lamp. To obtain it, the biodose is determined in several (8-10) healthy individuals. The arithmetic mean will be the biodose; it is usually determined once every 2-3 months.