UV Radiation Therapy Lecture 4 PDF

1 Electrotherapy II - PTBA 334 Lect. 4 Ultravilot Radiation Therapy (UVR) Presented by: Dr. Haitham Elessawy  2 § are electromagnetic radia...

1 Electrotherapy II - PTBA 334 Lect. 4 Ultravilot Radiation Therapy (UVR) Presented by: Dr. Haitham Elessawy  2 § are electromagnetic radiations lie between visible light & x-ray § wavelengths extended from 400 nm to 100 nm § are absorbed within first 1 to 2 mm of human skin § most of physiologic effects are superficial UV introduction § don’t produce heat, produce physiological effects by nonthermal mechanisms, § its effects are mainly chemical § used to treat various skin disorders § Divided into three ranges: UVA, UVB, UVC  3 The Electromagnetic Spectrum  4 Classification of UVR Type Wavelength UVA (long) 315 - 400 nm UVB (medium) 280 – 315 nm UVC (short) Below 280 nm (Germicidal)  5 § The natural source of UVR is the sun. § UVR is produced artificially for therapeutic purpose by the passage of electric current through an ionized vapor , often mercury vapor. § UVR are usually produced by mercury vapor lamps as follow: Production of Ø These lamps consists of a Quartz burner tube Ultra-Violet evacuated of air and containing traces of argon gas and mercury under low pressure (to allow gas to conduct Radiations current) Ø An electrode is inserted at each end of the burner tube. Ø The current is applied to the electrodes , the mercury vaporizes and the passage of the electron through the vapor establishes the UVR arc. 6  7 § UVR are absorbed by the skin. It penetrates the skin to a maximum depth of 2 mm, so that all UVR will be absorbed by the cells in the epidermis and the superficial dermis. § UV has been shown to cause skin erythema, Physiological tanning, epidermal hyperplasia, and vitamin D synthesis. effect of UVR § It is thought that these effects are the result of absorption of electromagnetic energy by the cells of exposed tissue, causing chemical excitation and facilitation of photobiological processes Its effects: A- Local effects B- General effects  8 A- Local Effects of UVR  9 vIt is the redness of the skin. vIt is the first observable effect of UVR. vIf UVR is absorbed by the skin, the energy released is sufficient to cause damage to the cells and intracellular structures 1- Erythema vThis damage depends on the wavelength and the amount of UV absorbed. vDamage 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  10 vThe greater the release of histamine likes substance the stronger and sooner the reaction. vThe shorter the wavelength, the greater the erythema (why). 1- Erythema v Erythema produced primarily in response to UVB. vThe erythema reaction has been used to classify doses of the UVR given to the patient. vThere are four visible degrees of erythema  11 Description of the degrees of Erythema Relation to E1 Dose Latent period Appearance Disappearance Pigmentation Desquamation E1 6-12 hrs Slightly < 24hrs Nil Nil 1 Pink) E2 4-6 hrs Red 48 hrs slight powdery 2.5 E3 1-4 hrs Fiery-red 72 hrs marked In Thin sheets 5 and painful E4 < 2 hrs angry red week or more marked Blister and 10 very thick sheets (Destructi painful ve dose)  12 § develops within two days of irradiation § UVR stimulates formation upward migration of melanin that present in the deep region of the epidermis into 2- Pigmentation more superficial layers. (tanning): § 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 tissue layers, it is thought that tanning is a protective response of the body. 13  14 § Epidermal hyperplasia is a thickening of the layer of the skin, occurs approximately 72 hours after exposure to UV radiation as a result of repairing 3-Growth of process following erythema. epithelial cells § Cells in the basal cell layer of the skin proliferate to replace the cell in the epidermis which are damaged (Epidermal or destroyed by UVR. hyperplasia): § This effect is thought to be caused the release of prostaglandin precursors leading to increased DNA synthesis by epidermal cells resulting in increased epithelial cell and cellular hyperplasia. § Thickening of the skin is three time than before UVR  15 § It is the casting off of dead cells from the surface of the skin which have been destroyed by UVR. § The extent of the desquamation is proportional to the 4-Desquamation intensity of the erythema (peeling): § With mild degrees of erythema, fine desquamation may be seen after repeated exposure to UV. § After its occurrence, the resistance of the skin to UVR is lowered.  16 5- Antibiotic effect § Mainly UVB enhance destruction of viruses, bacteria, (bactericidal and other small organisms found on the skin surface. effect):  17 B- General Effects of UVR  18 § Vit.D is accelerated by UVR as the skin absorbs UVB radiation in the sunlight and coverts provitamin D in 1- Formation skin, such as 7-dehydrocholestrol , to vitamin D3. (production) of § Vit.D3 in its active form acts on the intestine to facilitates absorption of calcium & phosphorus into vit D the blood stream and act on bone to facilitate calcium exchange and bone formation to prevent rickets.  19 § The resistance of the body to infection is increased (enhanced), particularly if general irradiation of UVRA is given. § This effect is due to stimulation of the Reticulo- endothelial system (the cells which ingest bacteria 2- The and produce antibodies against bacteria and toxins). esophylactic effect  20 Continued exposure to strong sunlight results in premature aging of skin as a result of: v Deeply penetrating UVA tends to cause collagen damage. v Photoaged skin is characterized by loss of elasticity, wrinkles, uneven pigmentation, brown spots, and a 3- Ageing of the leathery appearance whereas chronologically aged skin skin (Solar without over exposure to UVR is smooth and free of blemishes, though some natural loss of tone and elasticity Elastosis) occurs. v thinning of the epidermis, loss of epidermal ridges v loss of melanocytes v dryness as result of poor function of sebaceous and sweat glands v wrinkling from lack of dermal connective tissue.  21 § UVR appears to trigger immunosuppressive effects, both locally and systemically 4-Immune § UVR destroys Langerhan's cells and stimulate the proliferation of suppressor T cells (lymphocytes) Suppressive that inhibit antibodies production. Effects § Prolonged exposure to UVR may contribute to the development of skin cancer due its immunosuppressive effects.  22 Acute effects of expose of eyes to UVC and UVB are conjunctivitis and photokeratitis. 5- Effects on §Conjunctivitis is the inflammation of membrane that cover the inside of eye lids. eyes § Photokeratitis is the inflammation of cornea that can result in sever pain.  23 Therapeutic Uses of UVR 1- Acne 2- Psoriasis 3- Incipient pressure areas 4-Wound healing 5- Eczema  24 Acne is a chronic inflammation of the sebaceous gland with blocking of its duct, especially affecting the face, chest and back. Effects of UVR will produce: § Desquamation opens the blocked pores and hair follicles, § Erythema improves the condition of the skin, 1- Acne § UVR stimulates growth of healthy epidermis, and destroys the infecting organism.  Psoriasis is a common benign, acute ,or chronic 25 inflammatory skin disease of unknown cause, characterized by bright red plaques with silvery scales, usually on the knee, elbow, and scalp, associated with mild itching. The therapeutic effect of UV in the treatment of this condition may be üinactivation of cell division and decrease the DNA synthesis in the cells of the skin with the resultant decrease in the proliferation of the skin cells. 2-Psoriasis ü Or: altered leukocyte behavior and immunological activity , as well as effects on cell metabolic function.  26 § UVR prevents the skin over an incipient pressure area from breaking down and produce an open, infected wound. UVR improves the skin condition, stimulates the growth of epithelial cells, and destroy surface bacteria. 3- Incipient pressure area  27 § UV may be used to promote the healing of non- infected and infected open wounds, such as surgical incisions, pressure areas, or ulcers, through the following: 4-Wound 1- stimulate epithelial cell hyperplasia healing 2- improve skin condition by increase blood supply 3-prevent infection by destruction of any surface organism. 4- destroy and remove infected material. § UVC is the frequency band most commonly chosen.  28 Eczema is an inflammatory response in the skin with associated edema. The patient suffers marked itching with redness, scaling, vesicles and exudation of serum on the skin. UVR helps to control this condition through: 5- Eczema -Erythema that improve skin condition -Antibiotic effect as it sterilize the skin surface.  29 Photo-chemotherapy is the treatment of skin disease by exposure to UVR combined with photosensitizing agent e.g. PUVA (psoralen plus UVA). The drug is given to the patient 2 hours before irradiation to UVA. The patient will become more sensitive to UVR which will produce an erythema at lower intensities than normal. Many disorders show partial or complete response to PUVA: Psoriasis, Eczema.  30 § Dermatological conditions: acute eczema, lupus erythematosis, § Hypersensitivity to sunlight (photo-allergy) § Febrile disorders § Recent deep x-ray therapy Contraindications § Pulmonary tuberculosis or tumors § Severe cardiac disturbances § Hyperthyroidism. § Erythema , if patient’s skin still present an erythema.  31 Thank You