Ultraviolet Radiation Therapy Overview

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Questions and Answers

What primarily causes erythema in response to UV radiation?

Absorption of UV radiation by the dermis

Chemical excitation of cell structures

Release of histamine from epidermal cells (correct)

Dilated blood vessels in the epidermis

Which statement is true regarding the relationship between UV wavelength and erythema?

Shorter wavelengths lead to greater erythema (correct)

Longer wavelengths cause greater erythema

Erythema is independent of UV wavelength

Shorter wavelengths result in lesser erythema

Which local effect of UV radiation is considered the first observable effect?

Skin tanning

Epidermal hyperplasia

Vitamin D synthesis

Erythema (correct)

What role does the energy released from UV absorption play in skin damage?

It leads to damage of intracellular structures Signup and view all the answers

What is primarily associated with the classifications of UV radiation doses administered to patients?

The intensity of erythema produced Signup and view all the answers

Which degree of erythema results in slight pigmentation and desquamation in powdery sheets?

E2 Signup and view all the answers

What is primarily stimulated by UV radiation that leads to pigmentation?

Upward migration of melanin Signup and view all the answers

What characterizes the appearance of E3 degree erythema?

Fiery-red and painful Signup and view all the answers

How long does desquamation last for individuals experiencing E4 degree erythema?

A week or more Signup and view all the answers

What is the primary effect of epidermal hyperplasia following UV exposure?

Thickening of the skin layer Signup and view all the answers

What time frame does E1 degree erythema manifest in response to UV exposure?

6-12 hours Signup and view all the answers

Which degree of erythema indicates a destructive dose of UV radiation?

E4 Signup and view all the answers

What triggers increased DNA synthesis in the epidermal cells following UV exposure?

Release of prostaglandin precursors Signup and view all the answers

What is the primary mechanism through which ultraviolet radiation (UVR) produces physiological effects?

Nonthermal chemical mechanisms Signup and view all the answers

Which range of UV radiation is categorized as UVC?

Below 280 nm Signup and view all the answers

What are the typical wavelengths of UVA radiation?

315 – 400 nm Signup and view all the answers

How deep does UV radiation typically penetrate the skin?

2 mm Signup and view all the answers

Which gas is commonly found in mercury vapor lamps used to produce UV radiation?

Argon Signup and view all the answers

What natural source primarily produces ultraviolet radiation?

The sun Signup and view all the answers

What is the main purpose of artificially producing UV radiation?

Therapeutic treatment of skin disorders Signup and view all the answers

What type of skin disorders is UV radiation primarily used to treat?

Superficial skin conditions Signup and view all the answers

What effect does UVR have on the skin's resistance to infection?

It increases resistance by stimulating immune cells. Signup and view all the answers

What is the primary role of UVB radiation in relation to the skin?

It enhances the destruction of small organisms on the skin. Signup and view all the answers

Fine desquamation due to repeated UV exposure is linked to which severity of skin reaction?

Mild erythema Signup and view all the answers

What is the result of deep penetration of UVA rays into the skin?

Collagen damage leading to premature aging. Signup and view all the answers

How does vitamin D3 produced in the skin affect the body?

It facilitates the absorption of calcium and phosphorus. Signup and view all the answers

What distinguishes photoaged skin from chronologically aged skin?

Photoaging causes loss of elasticity and pigmentation changes. Signup and view all the answers

When does the desquamation process become noticeable?

Following mild degrees of erythema. Signup and view all the answers

Which condition is associated with overexposure to UVR?

Premature aging and photoaged skin characteristics. Signup and view all the answers

What is a potential consequence of prolonged exposure to UV radiation on the immune system?

Proliferation of suppressor T cells Signup and view all the answers

Which of the following describes the primary effect of UV radiation on the skin's appearance?

Reduction in dermal connective tissue Signup and view all the answers

How does UV radiation affect the treatment of acne?

Stimulates desquamation of the skin Signup and view all the answers

What causes photokeratitis as an acute effect of UV exposure on the eyes?

Inflammation of the cornea Signup and view all the answers

Which condition is characterized by bright red plaques with silvery scales?

Psoriasis Signup and view all the answers

What side effect does UV radiation potentially have on Langerhan's cells?

Destruction of the cells Signup and view all the answers

What is a common therapeutic use of UV radiation for wound healing?

Promotion of epidermal growth Signup and view all the answers

Which of the following is NOT listed as a therapeutic use of UV radiation?

Skin cancer Signup and view all the answers

What is the primary benefit of UVR in preventing the breakdown of the skin over an incipient pressure area?

Stimulates growth of epithelial cells Signup and view all the answers

Which of the following statements about UVC is correct?

UVC is the most commonly chosen frequency band for wound healing. Signup and view all the answers

What effect does UVR have on eczema?

It sterilizes the skin surface and controls erythema. Signup and view all the answers

What is the purpose of combining UVR with photosensitizing agents in photo-chemotherapy?

To ensure lower doses of UVR can produce an erythema effect Signup and view all the answers

Which of the following conditions is a contraindication for UVR treatment?

Pulmonary tuberculosis Signup and view all the answers

Which of the following actions does UVR NOT perform in wound healing?

Increasing skin sensitivity to UV radiation Signup and view all the answers

What clinical condition can utilize PUVA therapy for treatment?

Psoriasis Signup and view all the answers

What adverse effect should be monitored if a patient has erythema during UVR treatment?

Continued presence of erythema without improvement Signup and view all the answers

Study Notes

Ultraviolet Radiation Therapy (UVR)

UVR is electromagnetic radiation between visible light and X-rays.
Wavelengths range from 400 nm to 100 nm.
UVR is mostly absorbed within the first 1-2 mm of human skin.
UVR's physiological effects are usually superficial and non-thermal, mainly chemical.
Used to treat various skin disorders.
Divided into three ranges: UVA, UVB, and UVC (germicidal).

The Electromagnetic Spectrum

Shows the range of wavelengths and frequencies of electromagnetic radiation.
UV is between visible light and X-rays.
Wavelengths and examples of their corresponding objects: 3 football fields, 10 feet, 3 meters, 3 centimeters, 1 inch, 30x hydrogen atom diameter.

Classification of UVR

Type	Wavelength (nm)
UVA (long)	315-400
UVB (medium)	280-315
UVC (short)	Below 280 (germicidal)

Production of Ultra-Violet Radiations

Natural source is the sun.
Artificially produced using mercury vapor lamps.
Lamps consist of a quartz burner tube, evacuated of air, containing traces of argon gas, and mercury under low pressure for current conduction.
Electrodes at each end of burner tube.
Applying current vaporizes mercury, and electron passage establishes UVR arc.

Physiological Effects of UVR

UVR penetrates skin to a maximum depth of 2 mm.
Effects include skin erythema (redness).
Causes tanning, epidermal hyperplasia and vitamin D synthesis.
These effects are believed to be from chemical excitation and photobiological processes.
Local effects such as redness and general effects such as vitamin D synthesis.

1- Erythema

The redness of the skin, and the first observable effect of UVR.
Energy released if UVR is absorbed causes damage to cells and intracellular structures.
Extent of damage depends on wavelength and amount of UVR absorbed.
Damage releases histamine-like substances that cause blood vessel dilation (capillaries).
Severity directly related to wavelength and intensity of the UVR.
There are four distinguishable degrees of visible erythema

2- Pigmentation (Tanning)

Develops within two days of irradiation.
UVR stimulates melanin (pigment) upward migration from deep epidermis to superficial layers.
Melanin acts as an umbrella over the cell nucleus, reducing penetration of UVR to deeper tissue layers.
Tanning is considered a protective response by the body.

3- Growth of Epithelial Cells (Epidermal Hyperplasia)

Thickening of the skin layer (hyperplasia) starting about 72 hours after UVR exposure.
Result of repairing process from erythema.
Proliferation of basal cells to replace damaged/destroyed cells.
Release of prostaglandin precursors increase DNA synthesis, leading to epidermal hyperplasia.
Skin thickening is three times greater than before UVR exposure.

4- Desquamation (Peeling)

Casting off of dead cells from skin surface that are destroyed by UVR.
Extent of peeling proportional to intensity of erythema.
Mild erythema may result in fine desquamation after repeated UVR exposure.
Resistance of skin to future UVR exposure decreases after desquamation.

5- Antibiotic Effect

Primarily UVB enhances destruction of viruses, bacteria, and microscopic organisms on skin's surface.

B- General Effects of UVR

1- Formation (Production) of Vitamin D

UVR accelerates vitamin D formation in skin by converting provitamin D in skin like 7-dehydrocholesterol to Vitamin D3.
Active Vitamin D3 enhances calcium and phosphorous absorption in the intestine.
Facilitates calcium exchange and bone formation, preventing rickets.

2- The Esophylactic Effect

Increases body's resistance to infection, especially with general UVR.
Occurs due to Reticulo-endothelial System stimulation.
Cells in this system ingest bacteria and produce antibodies.

3- Ageing of the skin (Solar Elastosis)

Prolonged exposure causes premature aging, due to:
- Damage to collagen by UVA causing loss of elasticity, wrinkles, and pigmentation.
- Thinning of epidermis.
- Loss of epidermal ridges and melanocytes.
- Dryness due to dysfunction of sebaceous and sweat glands.
- Wrinkles from the lack of dermal connective tissue.

4- Immune Suppressive Effects

UVR triggers immunosuppressive effects (both local and systemwide).
Destroys Langerhans cells, stimulating suppressor T cells that prevent antibody production.
Prolonged exposure can increase risk of skin cancer due to suppression effect.

5- Effects on Eyes

Acute exposure to UVC and UVB may lead to:
- Conjunctivitis (inflammation of inner eyelid membrane).
- Photokeratitis (inflammation of the cornea, possibly with severe pain).

Therapeutic Uses of UVR

Acne, Psoriasis, Incipient pressure areas, Wound healing, Eczema.

Acne

Chronic inflammation of sebaceous glands with duct blockage.
UVR treatments open pores and follicles, improve skin condition, stimulates healthy epidermis growth, and destroys infection.

Psoriasis

Inflammatory skin disease with red plaques and silvery scales.
UVR therapies target to inhibit cell division, decrease DNA synthesis, or alter immune response.

Incipient Pressure Area

Early stage pressure sores prevented from infection and open wounds by UVR stimulation of epithelial cells and destruction of surface bacteria.

Wound Healing

UVR, especially UVC, promotes healing of infected and non-infected wounds by increasing epithelial cell production (hyperplasia), increasing blood supply, preventing infection, and destroying infected tissues.

Eczema

Inflammatory skin response, with itching, redness, and scaling.
UVR improves condition with erythema and antibiotic effect. Sterilization of skin surface is part of the treatment process.

Photo-chemotherapy

A treatment strategy for skin disorders using a photosensitizing drug (eg. psoralen) with UVA radiation.
The drug increases skin sensitivity to UVA.
Used to treat disorders like psoriasis and eczema

Contraindications

UVR therapy may be contraindicated in certain conditions like acute eczema, lupus erythematosus, photo-allergy, fever, recent x-ray treatments, pulmonary tuberculosis, tumors, cardiovascular diseases, hyperthyroidism, and present skin redness.

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Description

This quiz covers the fundamental concepts of ultraviolet radiation (UVR), including its classification, properties, and applications in treating skin disorders. Learn about the different types of UVR, their respective wavelengths, and their role in the electromagnetic spectrum.