Lecture 4 Ultraviolt Radiation PDF

Ultraviolet Radiation (UVR) Definition -Ultraviolet Radiation is electromagnetic rays with wave length between 400-100 nm. It lies between the visible light and x-ray in the electromagnetic spectrum. Natural source of UVR is SUN. - Its effects are mainly chemical in contrast to t...

Ultraviolet Radiation (UVR) Definition -Ultraviolet Radiation is electromagnetic rays with wave length between 400-100 nm. It lies between the visible light and x-ray in the electromagnetic spectrum. Natural source of UVR is SUN. - Its effects are mainly chemical in contrast to the pure heating effect of the IRR. Classfication of UVR -It is subdivided according to wavelength into: Type Wave length UVA (long wave length) 400-315 nm UVB (medium wave length) 315-280 nm UVC (short wave length) 280-100 nm  Both UVA and UVB reach the earth from the sun. However, UVC is completely absorbed by the ozone layer and doesn’t reach the earth as it is the most harmful to living organisms.  UVA can also be used to treat certain skin conditions like psoriasis and eczema.  UVB can also stimulate the production of vitamin D, which is essential for strong bones and a healthy immune system. 1  Physiological effect of UVR  UVR is absorbed by the skin. It penetrates the skin to a maximum depth of 2mm, so that all UVR will be absorbed by the cells in the epidermis and the superficial dermis.  The effects produced by the absorption of UVR are primarily local, although some general effects occur if larger areas are treated with high doses. A- Local effects: Local effects which produced locally in the area: 1-Erythema: It is reddening of the skin.  First observable effect of UV Irradiation.  When UVR is absorbed by the skin, the energy released is sufficient to cause damage to the cells and intracellular structures.  This damage depends on the wavelength and the amount of UV absorbed. 2  Damage of cells causes the release of histamine like substance from the epidermis and superficial dermis that accumulated around blood vessels in skin to make dilatation of capillaries.  The greater the histamine likes substance the stronger the reaction.  The more exposure to UVR The more chemical reaction and the more erythema the erythema reaction has been used to classify doses of the UVR given to the patient. There are four visible degrees of erythema. Degree of erythema post ultraviolet therapy: 1. First degree of erythema (Dose E1): It causes mild pink appearance of the skin which lasts for up to 24 hours with no presence of skin edema or discomfort. E1 is also called as MED - Minimal erythema dose. It is the smallest dose of ultraviolet radiation to result in erythema that is just detectable by eye. 2. Second degree of erythema (Dose E2): It causes definite pink red appearance of the skin that blanches on pressure which lasts for up to 2 days with no edema but slight soreness and irritation of the skin and powdery skin desquamation. 3.Third degree of erythema (Dose E3): It causes very red skin appearance with no blanch of skin on application of pressure, it lasts for 3 to 5 days. Post dosage some edema is present at the area of application, also the application area feels hot and painful with thin sheet like desquamation of skin. 3 4.Fourth degree of erythema (Dose E4): It leads to angry red appearance of the skin which lasts for a week. It also leads to formation of blisters on the skin which is very painful. It also causes thick sheet like desquamation of skin. Comparison of erythema of IRR and UVR 2-Pigmentation (tanning):  The pigmentation commonly follows an erythema reaction.  The pigmentation of the skin develops within two days of irradiation by UVR.  UVR stimulates melanocytes that present in the deep region of the epidermis to secrete melanin and upward migration of melanin already formed into more superficial layers.  The melanin forms as umbrella over the nucleus of the cell to protect it from UVR, so pigmentation reduces the penetration of UVR to deeper 4  tissue layers, it is thought that tanning is a protective response of the body. 3- Growth of epithelial cells (hyperplasia):  Epidermal hyperplasia is a thickening of the epidermis occurs approximately 72 hours after exposure to UV as a result of repairing process following erythema.  UVR stimulate reproduction of the cells in the basal cell layer of the epidermis (keratinocytes) to replace the cell in the epidermis which were damaged or destroyed by the UVR.  Thickening of the skin is three times than before UVR. 4- Desquamation (peeling):  Itis the casting off of dead cells from the surface of the skin which have been destroyed by the UVR.  The extent of the desquamation is proportional to the intensity of the erythema. 5 5-Antibiotic effect (bactericidal effect): Destructive effects of ultraviolet radiation include the destruction of viruses, bacteria, and other small organisms on the skin surface such as FUNGI commonly found in wounds. B- General effects of UVR. 1. Formation (production) of vitamin D  Vitamin D formation is accelerated by UVR as the skin absorb UVB radiation, and converts provitamine D in skin such as 7- Dehydrocholestrol to into Vitamin – D3 through chemical reaction.  Vitamin D3 is required to assist in the absorption of calcium and phosphorous from the intestine to blood stream and act on bone to facilitate calcium exchange and bone formation to prevent rickets. 6  2. Prophylactic effect:  The resistance of the body to infection is increased because of the stimulation of reticuloendothelial system. (the cells which ingest bacteria and produce antibodies against bacteria and toxins). 3. General Tonic Effect  Appetite & sleep being improved  Nervousness and irritability decreased. 5. Ageing of the skin:  Prolonged exposure to strong UVR can result in premature ageing of skin. There is dryness as result of poor function of sebaceous and sweat glands, and wrinkling from lack of dermal connective tissue. 6-Effect on eyes: The acute effects of expose of eyes to UVC and UVB are:  An inflammation of the membrane that lines the insides of the eye lids.  An inflammation of cornea that can result in severe pain. 7  Therapeutic effects and indications UVR is used in the treatment of some dermatological condition, infected and non-infected skin lesions. 1) Acne:  Acne is a chronic inflammation of the sebaceous gland with blocking of its duct especially affecting the face, chest and upper back.  The effects of the UVR will produce; erythema to improve the condition of the skin, stimulation of growth of healthy epidermis, desquamation to open the blocked pores and hair follicles, and antibiotic effects to destroy the infecting organism.  Ultraviolet radiation is given in E2 doses for acne 2) Psoriasis:  Psoriasis is a skin disease of unknown cause that causes a rash with itchy, scaly patches, most commonly on the knees, feet, elbows, trunk and scalp. 8   In this state the aim of UVR irradiation is to decrease or slows down excessive skin cell growth which causes the silvery scaly patches & improves the skin condition.  Ultraviolet rays are beneficial for the treatment of psoriasis given once a day.  Ultraviolet radiation is given in E2 doses for Psoriasis 4) Wound healing:  UVR may be used to promote the healing of non-infected and infected open wounds, such as surgical incisions, pressure areas, or ulcers.  An E3 dose is sufficient but for the treatment of chronic infection, ultraviolet radiation at high doses are helpful. An E4 dose can be used for treating infected open wounds and pressure ulcers.  UVR may be used to promote the healing of non-infected and infected open wounds by:  Promote healing by stimulate epidermal cell hyperplasia  Improve skin condition by increasing blood flow  UVR prevent infection by destroying and removing infected material  Increasing vitamin D production. 9  ULCERS PRESSURE AREAS INCISIONS 5) Eczema:  Eczema is inflammatory skin disease that causes itchy, red, dry, and irritated skin.  UVR treatment will help to control this condition through Erythema which will improve the skin condition  Antibiotic effect: sterilize the skin surface.  These patients are benefited by mild doses of UVR  Ultraviolet radiation is given in E2 doses for Eczema 10 Contraindications: 1. Dermatological conditions: certain conditions such as acute eczema, acute Psoriasis and acute dermatitis may be exacerbated by UVR. 2. Hypersensitivity to sunlight (photo allergy): patients who are known to react adversely to even minimal exposure to sunlight should not be treated with UVR. 3. Recent deep x-ray therapy (DXT): if the area to be treated with UVR has received deep x-ray therapy within the preceding 3 months. 4. Pulmonary tuberculosis or tumors: in the area to be treated may be exacerbated by the effects of the UVR. 6. Severe cardiac disturbances. 7. Severe diabetes. 8. Erythema: if the patient's skin still presents an erythema, the reaction to UV is dramatically increased consequently, UV is contraindicated until the erythema has subsided. Dangers: 1-Shock: the machine should be earthed and main power cord insulation intact. 2-Damage to the eyes: irradiation of the eyes with UVR. So the eyes of both patient and therapist must be protected. 3-Overdosage: there is a risk of producing an U.V burn due to: 11 *Too close to the lamp *Too long an exposure. Practical application of UVR  When applying UV radiation, therapist must first determine the individual patient's sensitivity to UV radiation by erythema dose, or dose response assessment. The dosage of UV light is prescribed according to an individual's skin sensitivity. Dose-Response Assessment:  It is used to assess the individual patients (ERYTHEMAL) reaction to UVR.  The basis for any calculation of any UVR dosage is the MED (Minimal Erythemal Dose). CALCULATION OF DOSAGE  E1/MED: E1 is also called as Minimal erythema dose. It is the basic of UV calculation which is determined for each individual patient by performing a skin test. Minimal erythemal dose (MED) or E1: The smallest dose producing erythema. It causes mild pink appearance of the skin within 6-8 hours after exposure that disappears within 24 hours after exposure. Second-degree erythema (E2): It causes pink red skin appearance with blanching of skin on application of pressure and powdery skin desquamation. It appears within 4-6 hours after exposure and disappear after 1 to 2 days. E2=MED X 2.5 12  Third-degree erythema (E3): It causes very red skin appearance with no blanch of skin on application of pressure, some edema is present at the area of application, with thin sheet like desquamation of skin. It appears within 2 -4 hours after treatment and disappear after 3 to 5 days. E3= MED X 5. Fourth-degree erythema (E4): Erythema with severe blistering and desquamation of skin. It appears after more than 2 hours after treatment and disappear after a week. E4= MED X 10. EXAMPLE: If the E1 dose of the patient is 25sec, calculate the E3 dose?  E1 dose = 25sec  E3 dose = 5 x E1  E3 dose = 5 x 25 = 125sec How to Determine the MED of UVR Skin Test 1. Patient and therapist wear UV protective glasses. 2. Remove all clothing and jewelry from area of the body. The areas usually used are the volar forearm, the abdomen, or the thigh. 3-Explain to the patient the procedures. 4- Tell the patient not to look to the lamp because of possibility of damage the eyes. 5-Assuming that there is no contraindication to U.V 6-Take a piece of cardboard approximately 4 by 20cm and cut three or six shape holes of at least 2cm² & 1cm apart for irradiation of UVR. 13 7- Place the cardboard on the test area and drape the area around the cardboard so that the surrounding skin will not be exposed to the radiation. 8- Set up the lamp 60 to 80 cm away from and perpendicular to, the area to be exposed. Measure and record the distance of the lamp from the area to be exposed. 9- Turn on the lamp. 11-Exposure the 3 holes at one time to UV for 5 seconds, then cover the 2 holes and leave one for 5 seconds then after 5 seconds cover 1 hole and leave the others for another 5 seconds. 12. According to this protocol, 1st opening will have been exposed for 15 seconds, the second for 10 seconds, and the third for 5 seconds. So the 1st opening would receive the longest exposure time & the last opening would receive the least amount of exposure time. 12. The patient is asked to record the response of the area for the 24 hours following exposure. The area that shows mild pink of the skin within 6-8 hours that disappears within 24 hours was treated with the MED. 14  The skin response to UVR depends on: 1-individual patient sensitivity 2-intensity of radiation source and distance of lamp to target 4-angle of incidence of radiation at skin 5-duration of exposure. 15  Selection of dosage level: The dosage level is selected according to the effects required for the treatment of the presenting condition. However, it is not recommended that large areas to be exposed to high doses of UVR. The following guidelines should be followed:- 1. An E1/MED – Given to the total body area (Whole body) as for calcium & phosphorous deficiency 2. An E2 - Can be given to up to 20% of total body area 3. An E3 – Can be given to up to 250 cm² of normal skin 4. An E4 – May only be given to an area up to 25 cm² for treating infected open wounds & pressure ulcers. Progression of dosage  An exposure to UVR should not be repeated until the erythema caused by a previous dose has faded. Doses are progressed as follows:-  To repeat an E1 25% of the preceding dose is added  To repeat an E2 50% of the preceding dose is added  To repeat an E3 75% of the preceding dose is added  To repeat an E4 100% of the preceding dose is added Examples of progression of dosage o If E1 is 30sec, find the second progression (P2E1)?  E1= 30sec  P1(Day one progression) E1 = E1 + 25% of E1 = 30 +30/4 = 30 + 7.5 =37.5sec  P2 (Day two progression) E1 = P1E1 + 25% of P1E1 = 37.5 +37.5/4 = 46.9sec 16  P2E1 = 47sec Frequency of treatment:- An E1 or MED may be given daily. An E2 should be given every second day. An E3 should be given twice weekly. An E4 may only be given once a week, or even once 2 weeks, provided the effect of the previous dose have subsided. Treatment Setup for UVR Treatment  Place patient in a well-supported, comfortable & relaxed position.  Expose the body part to be treated, clean it, have patient remove all jewelry from the area, and make sure there are no local contraindications present for the treatment  Patient and therapist should wear UV protective glasses to protect the eyes.  Place lamp PERPENDICULAR to the area being treated & a distance of 60 to 80 Cm from the site.  Switch on lamp and begin timing simultaneously  As the treatment time is over, switch OFF the UVR generator & move away from the patient  Inspect the treatment area for any adverse reactions like blisters/burns  In the treatment for psoriasis that consists of ingestion of (Certain drugs) as oral psoralen, when patients expose the affected site to a UV light source. These drugs increases the patient's sensitivity to UVR. The patient will become more sensitive to UVR which will produce an 17  erythema at lower intensities than normal. So, the drug is given to the patient 2 hours before irradiation to UVR. Particular considerations for local UVR to the face  Ask the patient to close the eyes and protect the eyelids with small pieces of cotton secured by petroleum jell.  When treatment is applied from the front, the tip of the nose is significantly nearer to the lamp than the rest of the face, so to avoid over treatment, a light of petroleum jelly may be applied.  If the face is treated from the side, the same applies to the ears. Application to face 18  Case Study Patient History The patient is a 38 - year - old woman with a chronic, infected sacrococcygeal pressure ulcer. She is confined to a wheelchair as a result of a spinal - cord injury. The ulcer was discovered 5 months ago and treated with traditional care and debridement with little success. Examination: The ulcer is infected and measures 3.7 cm wide by 4.1 cm long by 1.5 cm deep Treatment:  Determine the MED of the patient.  Fourth-degree erythema (E4) dose is required to stimulate healing and reduce the infection.  Lamp is held perpendicular to the wound at a distance of 60cm from the surface.  A 2 - mm - thick layer of petroleum jelly was applied to the skin around the wound, and a layer of heavy paper toweling with a window cut in it to expose the wound was used to cover it.  Treatment was repeated given once a week for a total of 12 treatments or until wound closure occurred.  Other treatment included daily wound cleansing and patient positioning to avoid pressure on the ulcer.  Treatment was ceased when wound closure occurred. 19