Ultra Violet Radiation
Table of Contents
Introduction
The sun emits Ultraviolet radiation(UVR) which can often have an effect on skin e.g. sunburn, but for therapeutic purposes, some form of generator is used. The ultraviolent spectrum may be divided into:
- UVA(315-400 nm)
- UVB(280-315nm)
- UVC(below 280nm)
Ultraviolent generators
High-pressure mercury vapor lamp
This is often a U-shaped glass tube. The burner is made of quartz: this material allows the passage of ultraviolet(UV), can withstand very high temperatures, and has a fairly low coefficient of expansion. Enclosed in the tube is argon gas at low pressure, a low pressure, and a small quantity of mercury in the tube, and an electrode is sealed into either end. surroundings the ends are two metal caps across which a high potential difference is applied in order to ionize the argon.
Argon is normally extremely stable and inert as it has a full outer shall of electrons, so the argon atoms must be ionized to pass a current through the tube. An electron from the outer shell of the atom produces a negative particle ( the electron )and a positive ion.
The movement of positive and negative particles in the burner produces an electric current. This current flow can be seen as a glow discharge flow across the tube. Now this mercury vapor itself becomes ionized.
Production of UVR is produced. At the same time, visible and infrared electromagnetic waves are produced, and ultraviolent emission reaches its peak.
Tridymite Formation
Sometimes quarts lead to the formation of tridymite {at high temperature}. Tridymite is opaque to UVR and therefore the total output of the lamp gradually falls as the proportion of tridymite increases.
Cooling
A considerable portion of output of the high-pressure burner is infrared, which when absorbed by human body is converted to heat. If the lamp is air-cooled the closest it can safely be placed to a patient is 50 cm, otherwise a burn may result. The burner is usually housed in a parabolic reflector, the position of which can be adjusted on a stand.
Kromayer lamp
A kromayer lamp is a water-cooled mercury vapor lamp. It eliminates the danger of infra-red rays as it does not produces infrared waves
ADVANTAGE – it is used in contact with tissue. The kromayer layer can be used for the treatment of sinuses and deep body cavities.
CONSTRUCTION
- It is completely enclosed in circulating distill water where it absorbs infrared.
- A pumping and cooling fan is incorporated in kromayer lamp to cool water
- After turn off – water circulating continued (5 min)
PROCESS – water circulation between two quarts window which allows UV to emerge out. This quartz conveys UVR to tip by total internal reflection.
Theraktin tunnel
The Theraktin tunnel is a semi-cylindrical frame in which are mounted four fluorescent tubes. Each tube is mounted in its own reflector in such a way that even irradiation of the patient is produced, allowing treatment of the whole body simultaneously. The spectrum of 280 – 400 nm.
PUVA apparatus
The term refers to ( Psoralen UltraViolet A ), four sides of a box totally surrounding the patient.
Dosageย
ย Dosage | E1 | E2 | E3 | E4 |
ย Erythema formation | ย 6-8 hours | 4-6 days | ย 2-4 days | less than 2 hours |
ย Erythema disapperance | Less than ย 24 hours | ย 2 days | ย 3- 5 days | Week |
colourย | ย Pinkish | ย Red | Peeling of skin , redness | Blister Apperance |
Indication of UVR
Acne
Acne is a skin condition that occurs when your hair follicles become plugged with oil and dead skin cell. Also called Ache Vulgaris.
An E2 dose of ultra violet radiation(UVR)ย may be given
Aim
- An erythema will bring more blood to skin and so improve the condition of the skin .
- Desquation (Peeling skin) will remove come domes ( the primary sign of acne , a small bump on skin ), thus reduces the number of lesion .
- sterilization effects of UVR .
Treatment of UVR
The condition returns within a few weeks of UVR. Unfortunately, it may get worse a week after UVR, as all the lesion in the skin reach their peak at the same time, whereas in the normal course of acne, some will be resolving as other develop.
Psoriasis
Psoriasis isย autoimmune condition that causes inflammation in your skin. The UVR is given .
Aim
- To decrease the rate of DNA synthesis in the cell of the skin
- Slow down their proliferation
Treatment OF UVR
it can be given using Leeds Regimen or PUVA
Leed regimen
- A Sub – erythemal dose ( half E1 ) is given to patient , using a Theraktin tunnel or air – cooled lamp at 100cm.
- The dose is repeated daily , increasing by 12 half each times .
Contraindication of UVR
- Hypersensitivity to sunlight: some patients react adversely to sunlight and are not treated with UVR.
- DXT: Deep X-ray therapy produces local hypersensitivity to UV and patients with this are not treated with UV
- Erythema: Erythema is an abnormal redness of skin or mucous membranes. Capillary congestion causes condition, and red splotches on hands or feet are classic.
- Eczema: A disease that makes your skin red and dry so that you want to scratch it
- Lupus erythematosus: Lupus erythematosus is an autoimmune disease in which the immune system attacks its own tissues, causing widespread inflammation and tissue damage in the affected organs.
- Herpes simplex: herpes simplex virus (HSV), known as herpes, is a common infection that can cause painful blisters or ulcer. It is a viral infection that causes genital and oral herpes. Many people live asymptomatic.
Precaution
- wear goggles
- eyes should be covered with cotton wool.
- 50 cm distance between patient and lamp .
- the therapist should be on alert , during treatment .
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