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Ultraviolet Therapy

Ultraviolet Therapy. Ultraviolet Radiation (UVR). In electromagnetic spectrum UVR ranges from 2000 to 4000 Å Divided into three ranges: UV-A- near UV- 3200 to 4000 Å Little or no physiologic effect UV-B- middle UV- 2900 to 3200 Å Associated with sunburn and age-related skin changes

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Ultraviolet Therapy

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  1. Ultraviolet Therapy

  2. Ultraviolet Radiation(UVR) • In electromagnetic spectrum UVR ranges from 2000 to 4000 Å • Divided into three ranges: • UV-A- near UV- 3200 to 4000 Å • Little or no physiologic effect • UV-B- middle UV- 2900 to 3200 Å • Associated with sunburn and age-related skin changes • UV-C- far UV- 2000 to 2900 Å • Bactericidal

  3. Ultraviolet Radiation • UVR apparatus most likely to be used would generate UVR in UV-B, UV-C or both ranges • UVR is absorbed within first 1 to 2 mm of human skin • Most of physiologic effects are superficial • Used to treat various skin disorders

  4. Effect On Cells • Exposure of skin to UVR causes chemical excitation of cells which leads to physiologic changes within these cells • Alteration of cell biochemistry and cellular metabolism which affects synthesis of DNA and RNA • This leads to alterations in protein and enzyme production

  5. Short-Term Effects on Skin • Skin consists of two layers • Epidermis • Contains keratinocytes which produce keratin,- fibrous protective protein of skin • Dermis • Papillary layer - rich blood supply • Reticular layer - heavy connective tissue containing fibroblasts, histocytes, and mast cells

  6. Erythema • Generalized response to UVR exposure culminates in development of an acute inflammatory reaction • End results of active inflammation are • Erythema- reddening of skin associated with sunburn • Pigmentation -tanning • Increased epidermal thickness

  7. Inflammation • Inflammatory response characterized by local vasodilation and increased capillary permeability causing erythema • Permits certain proteins to move from capillaries into dermis resulting in a change in osmotic pressure • Water drawn into area and edema occurs • Phagocytic cells eliminate dead cells

  8. Photosensitization • Over sensitization to UVR as a result of excitation of a chemical by UVR exposure • Acute effects of UVR exposure can be exacerbated if certain chemicals or medications are present on skin or in body

  9. Tanning • Increase of pigmentation in skin • Protective mechanism activated by UVR exposure • Increase of melanin (pigment responsible for darkening) within skin causes tan • Functions as a biologic filter of UVR • By scattering radiation • By absorbing UVR • By dissipating absorbed energy as heat

  10. Tanning • Immediate tanning occurs following UVR exposure • Appears most often in darkly pigmented individuals • Represents the darkening of melanosomes already present in the skin • Begins to fade 1 hour after exposure and is hardly noticeable 3 to 8 hours

  11. Tanning • Delayed tanning results from formation of new pigment (melanin) through melanogenesis • Delayed tanning usually becomes apparent 72 hours after UVR exposure

  12. Artificial Tanning Devices • Manufacturers claim tanning beds produce only UVR in UV-A spectrum and are safe • Production of this type of UV-A generator is largely unregulated • Effects of long-term exposure to UV-A are unknown • Caution should be exercised before using an artificial source to expose to UVR

  13. Long-Term Effects on Skin • Premature aging of the skin • Dryness, cracking, and a decrease in elasticity of skin resulting from epidermal solar elastosis • Alteration in the skin's elastic fibers • Linked to UVR-induced DNA damage

  14. Long-Term Effects on Skin • Skin cancer • Most common malignant tumor found in humans • Damage to DNA suspected as cause • Major types of skin cancer • Basal cell carcinoma( rarely metastasizes) • Squamous cell carcinoma (metastasizes in 5%) • Malignant melanoma (Usually metastasizes • Rate of cure exceeds 95% with early detection

  15. Sunscreens • Sunscreen’s effectiveness in absorbing sunburn inducing radiation is expressed as sun protection factor(SPF) • SPF of 6 indicates you can be exposed to UVR six times longer than without a sunscreen before receiving a minimal erythemal dose

  16. Effect On Eyes • UVR exposure of the eyes causes an acute inflammation called photokeratitis • Delayed reaction occurring within 6 to 24 hours • Conjunctivitis develops, accompanied by erythema of adjacent facial skin • Sensation of a foreign body on eye • Photophobia • Increased tear production • Spasm of the ocular muscles

  17. Systemic Effects • Photosynthesis of vitamin D following irradiation of skin by UVR in UV-B range • UVR can be used as treatment for disorders of calcium and phosphorus metabolism, such as rickets and tetany • Treatment of choice for such problems is dietary supplementation

  18. Ultraviolet Generators • Carbon arc lamp • Xenon compact arc lamp • Fluorescent ultraviolet lamp (blacklight) • Mercury arc lamp

  19. Carbon Arc Lamp • Composed of two carbon electrodes • Two electrodes move slightly apart causing current to arc across small gap • UVR is emitted between 3500 and 4000 Å • Electrodes gradually burn and must be replaced • Burning is noisy and causes an unpleasant odor

  20. Xenon Compact Arc Lamp • Composed of compressed xenon gas enclosed in a vessel • Electric arc passed through gas • Gas is heated to 6000° C • Emits infrared, visible, and UVR in range of 3200 to 4000 Å

  21. Fluorescent UV Lamp(Blacklight) • Low-pressure mercury lamp • Tube of UV-transmitting glass coated with phosphors • Phosphors are fluorescing substances that absorb the UVR and then reemit it at a longer wavelength • UVR emitted ranges from 3000 to 4000 Å

  22. Mercury Arc Lamp • Most likely kind of UVR lamp to be used • Either low-pressure or high-pressure mercury arcs • Mercury contained in a quartz envelope • An electric arc passes through vaporizing mercury • At 8000° C atoms become incandescent and emit ultraviolet, infrared, and visible light

  23. Mercury Arc Lamp • High-pressure = Hot Quartz • Most of UVR produced falls within UV-B range • Mainly used to produce erythema and accompanying photochemical reactions

  24. Mercury Arc Lamp • Low-pressure = Cold quartz lamp • Temperature of the quartz envelope is about 60° C • UVR spectrum limited to 1849 Å and 2537 Å • Does not require a warm up or cool down period, and is used mainly where bactericidal effect of UVR is desired

  25. Techniques of Application • Effectiveness of lamp assessed by determining skin sensitivity to UVR • Measured by the minimal erythemal dose (MED) • Exposure time needed to produce a faint erythema of the skin 24 hours after exposure • Question patient regarding photosensitizing drugs • Area of skin to be tested should have pigmentation similar to area to be treated

  26. Measuring MED • Patient is draped except for test site • Piece of paper with five cutouts 1” square and 1”apart placed over the test site • Height of lamp from patient adjusted to same level as for treatment • Shutters are opened and cutouts exposed at 15-sec intervals 15, 30 , 45, 60, and 75 secs.

  27. Determining MED • Patient returns in 24 hours and a visual inspection determines MED • Areas tested that reveal no erythema 24 hours after testing have received a suberythemal dose • Areas showing erythema at 24 hours have received a minimal erythemal dose. • Erythema still present at 48 hours = 1st degree erythemal dose • Erythema persists from 48-72 hours = 2nd degree erythemal dose • Erythema lasts past 72 hours= 3rd degree erythemal dose

  28. Determining MED • 1st-degree and 2nd-degree doses can be estimated • 1st-degree erythemal doses approximately correspond to 2.5 times minimal erythemal dose • 2nd-degree doses correspond to 5 times minimal erythemal dose

  29. Determining MED • Since human skin adapts to UVR exposure, MED will gradually increase with repeated treatments • Necessary to gradually increase exposure time to achieve the same reaction • Once determined it is increased 5 seconds per treatment • Height of lamp remains constant

  30. Positioning The Lamp • Apply cosine law and inverse square law • Distance of lamp must be kept constant if intensity of treatments is to be equal • Generally standardized at each clinic usually ranging from 24 to 40 inches

  31. Treatment Technique • Patient should be draped and wear eye goggles • Consistency in positioning of lamp is critical • Must be the same as in MED test • Clinician must also wear goggles • Open lamp shutters and begin timing simultaneously

  32. Clinical Applications • Most common use of UVR is in treatment of dermatologic conditions such as psoriasis and acne and hard to cure infectious skin conditions such as pressure sores • Development of oral and topical medications has greatly reduced the use of ultraviolet

  33. Acne Aseptic wounds Folliculitis Pityriasis rosea Tinea capitum Septic wounds Sinusitis Psoriasis Pressure sores Osteomalacia Diagnosis of skin disorders Increased vitamin D production Sterilization Tanning Hyperplasia Indications for Ultraviolet Therapy

  34. Porphyrias Pellagra Lupus erythematosus Sarcoidosis Xeroderma pigmentosum Acute psoriasis Acute eczema Herpes simplex Renal and hepatic insufficiencies Diabetes Hyperthyroidism Generalized dermatitis Advanced arteriosclerosis Active and progressive pulmonary tuberculosis Contraindications for Ultraviolet Therapy

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