Electromagnetic radiation consists of electric and magnetic fields. It can be categorized based on wavelength and frequency, with higher frequency radiation like X-rays and gamma rays being ionizing. Ultraviolet radiation is a type of electromagnetic radiation that is divided into UVA, UVB, and UVC bands. UVA and UVB reach the earth from the sun and can cause effects like erythema, tanning, and vitamin D synthesis in skin. Prolonged exposure to UV radiation can lead to premature skin aging and skin cancers. Precautions must be taken when using UV radiation therapeutically to avoid burns and other adverse effects.

2. Electromagnetic radiation is composed of electric and
magnetic fields perpendicular to each other .
Electromagnetic radiation can propagate without the need
of medium.
All living organisms are continuously exposed to
electromagnetic radiation from sun, electric appliances,
computers.
Electromagnetic radiations are categorized according to
there wavelength and freq. which are inversely
proportional to each other.
All nonionizing radiation can't break molecular bounds or
produces ions, and can therefore be used for therapeutic
medical applications.
Higher freq. electromagnetic radiation such as x-rays and
gamma rays is ionizing and can break molecular bounds to
form ions.
Ionizing radiation can also inhibit cell division and is
therefore either not/or used in very small doses for imaging
or to destroy tissues.

3. Ultraviolet radiation:
Is an electromagnetic radiation with wave length
from 400 nm to below 290 nm. And freq. range
from 7.5 x 1014 to 1015 Hz
UV radiation lies between visible light and x-ray
UV radiation is divided into three bands:
UVA: 400-320 nm
UVB: 320-290 nm
UVC: less than 290 nm
UVA: also known as long wave UV, is non ionizing
and produce fluorescence in many substances.
UVB: or middle wave UV is also non ionizing, it
produce the most skin erythema.
UVC: short wave UV, is ionizing and germicidal.
Both UVA & UVB reach the earth from the sun,
however, UVC is filtered out by the ozone layer.

4. The intensity of UV radiation reaching the skin
is greatest when a high power lamp is used,
when the loop is close to the pt. and when the
radiation beam is perpendicular to the surface
of the skin. Penetration is deepest for UV
radiation with the highest intensity, longest
wave length and lowest freq. thus UVA
penetrate farthest and reaches through several
millimeters of skin, while UVB and UVC
penetrate less deeply and are almost entirely
absorbed in the superficial epidermal layers.
The penetration of UV radiation is also less
deep if the skin is thicker or darker.

5. Effect of UV radiation:
1. Erythema production: erythema or redness of
the skin due to dilatation of the superficial
blood vessels caused by the release of
histamine, is one of the most common effects
of exposure to UV radiation, UVB is most
portent than UVA, the precise mechanism is
unknown, however, it is known that this effect
is mediated by prostaglandin release from the
epidermis, and it may be also related to DNA
damaging effect of UV radiation.
2. Tanning: a delayed pigmentation of the skin
occur in response to UV radiation exposure.
This effect is the result of increase production
and upward migration of melanin granules and
oxidation of premelanin in the skin.

6. Effect of UV radiation .. cont:
3. Epidermal hyperplasia: a thickening of the
superficial layer of the skin, occurs 3 days after
exposure to UV radiation. This effect is thought
to be caused by the release of prostaglandin
precursors leading to increasing DNA synthesis
by epidermal cells, resulting in ↗ epithelial cell
turnover and cellular hyperplasia.
4. Vitamin D synthesis: UV irradiation of the skin is
necessary for the conversion of provitamin D to
vitamin D, rickets may result of inadequate
exposure to UV, inadequate intake of vitamins
or poor kidney function. For most individuals
the exposure to UV or sunlight is sufficient to
maintain adequate level of vitamin D
production, UV exposure may be inadequate in
some bedridden pt.
Ultraviolet irradiation
induces keratinocyte
proliferation and
epidermal hyperplasia
through the activation
of the epidermal
growth factor
receptor

7. Clinical indication fot the use of UV radiatiuon:
1. Psoriasis: the therapeutic effect of UV radiation in the ttt of
this conditions thought to be due to it’s ability to inactivate
cell division on inhibition the DNA synthesis and mitosis of
hyper proliferating epidermal cells.
2. Wound healing: UV may be used for ttt of wound that have
not respond to or are inappropriate for other types of ttt UVC
may be used to enhances epithelialization, destroy bacteria,
cause minimal erythema or tanning ( but has low carcinogenic
effect). UV thought to facilitate wound healing by increasing
epithelial cell turnover, causing epidermal cell hyperplasia,
accelerating tissue formation, increasing blood flow, killing
bacteria, increasing vit. D production and promoting sloughing
of necrotic tissues.
3. Other indications: scleroderma, vitiligo, eczema and atopic
dermatitis.

8. Contraindication for the use of UV
radiation:
1. Irradiation of the eyes: should be
avoided because it can damage the
eyelids, the cornea and the lens.
2. Skin cancer: because it is known to be
carcinogenic.
3. Not to be used in pt. with pul.
Tuberculosis, cardiac, liver or kidney
diseases.
4. SLE and fever; this conditions may be
exacerbated by exposure to UV
radiation.
Pterygium

9. Precaution for UV use
1. Photosensitizing medications: care should be taken when applying UV radiation
to pt. who are taking these medicament; include ( sulphonamide, tetracycline,
quinolone, amiodarone, gold therapy, phenothiazines and psoralen.)
While the pts. Are taking these medicaments they have increased sensitivity to UV
radiation resulting in decrease in the minimal erythemal dose & an increase risk of
burning.
2. Photosensitive pts.: some pts. Particularly those with fair skin and hair coloring
and those with red hair are particulary sensitive to UV exposure, because they
have accelerated & exaggerated skin response( low level of UV should be used
when determining the minimal erythemal dose and for ttt.
3. Pts. who have had recent X-ray radiation; because the skin is more susceptible to
develop malignancies.
4. No dose of UV should be repeated until the effects of the previous dose have
disappeared. To minimize the risk of burns or an excessive erythemal response.

10. Adverse effects of UV:
1. Burning: will occure if too high dose is
used. Can usually be avoided by carful
assessment of the minimal erythemal dose
prior to initiating ttt and by avoiding
further exposure when signs of erythema
form a prior dose are still present.
2. Premature aging of skin: chronic exposure
to UV radiation, including sunlight is
associated with premature aging of the
skin. The skin may dry, coarse, leathery
appearance with wrinkling and
pigmentation abnormalities, may be due
to collage degeneration that accompanies
long term exposure to UV radiations.
A 69-year-old man who drove a
delivery truck for 28 years shows
damaged skin on the left side of
his face(more exposed to sunlight)

11. Adverse effects of UV ..cont:
3. Carcinogenesis: prolonged
exposure to UV may be a risk
factor for the development of
squamous cell and basal cell
carcinoma and malignant
melanoma.
4. Eye damage: UV of the eyes
can cause photokeratitis,
conjunctivitis and cataract.

12. Application techniques:
How to determin the minimal
erythemal dose (MED): the smallest
dose producing erythema with 8 hs
after exposure that disappears within
24 hs after exposurs.
1. Place UV opaque glasses on the pt. and clinician.
2. Remove all clothing and wash an area of the body
least exposed to natural sunlight. The areas usually
used are the volar forearm, abdomen or the buttocks.
3. Take a piece of cardboard approximately 4 x 20 cm
and cut four square holes 2 x 4 cm in it.
4. Place the cardboard on the test area drape the area
around the cardboard so that the surrounding skin
will not be exposed.

13. Application techniques ..cont:
5. Setup the lamp 60-80 cm away from and perpendicular
to the area to be exposed.
6. Cover all except one of the hole in the cardboard.
7. Turn the lamp ON, when it reach full power, direct the
beam toward the area to be exposed and start the
timer.
8. After 120 sec uncover the 2nd hole .. Then after another
60 sec uncover the 3rd hole .. Then after 30 sec the 4th ..
After another 30sec turn the lamp OFF.
According to this protocol the 1st hole has been exposed for
240sec, the 2nd = 120sec the 3rd = 60sec and the 4th =
30sec.
The pt. should be observed during 24 hs  mild reddening
of the skin after 8 hs that disappear within 24 hs was
treated with the minimal erythemal dose (MED).