Ultraviolet Radiation

UVR has a frequency of ______________

1.65x10^15 to 7.5x10^ 14Hz

True/False: UVA is farther from visible light while UVC is closer to visble light

False

UVA is AKA

Long-wave UV; Near UV

UVB is AKA

middle-wave UC

UVC is AKA

Short-wave UV; Far UV

UVA wavelength

(315) 320-400 nm

UVB Wavelength

(280) 290 - 320

Use of UVA

Blacklight *most intense heating effect

UVB use

Skin erythema; sunburn

UVC use

Germicidal; Bactericidal

Least harmful UV; can be easily reflected back

UVC

True/False: UVR is also a thermal agent

False; UVR has photochemical effect on tissues

UVR is absorbed within the __________ of human skin

first 1-2 mm (0.22mm)

80-90% of UVR is absorbed in the?

dermis

True/False: UVR has ionizing effects

True

Excessive natural UVR exposure can cause __________

1. Cutaneous malignant melanoma

2. Basal-cell carcinoma

3. Squamous-cell carcinoma

Factors Affecting UV penetration

1. Intensity of radiation

2. Wavelength of radiation

3. Power of radiation source

4. Exposure duration

5. Distance of radiation source

6. Frequency

7. size of area

8. Thickness of Skin

9. Pigmentation of Skin

Which factors directly affects UV depth of penetration (higher = deeper penetration

1. Intensity

2. Wavelength

3. Power of radiation source

4. Exposure duration

5. Closer Distance

6. Light skin

Which factors are indirectly proportionate to UV depth of penetration

1. Farther distance = superficial penetration

2. Frequency

3. Size of area

4. Thickness of Skin

5. Darker complexion

(Equipment)

• Burner (argon gas and mercury)

• ↑ pressure and temperature

• (+) erythema and pigmentation

• Applied >15” from the area (farther from pt)

• No need for warm-up

Hot Quartz

• Quartz tube with mercury (ionized vapor)

• ↓ pressure and temperature

• Minimal erythema and (-) pigmentation

• Application at close proximity

• Needs 5 min warm-up

Cold Quartz

Mercury Arc Lamps vs Fluorescent Lamps

Mercury Arc Lamps	Fluorescent Lamps
Small	Long
Emit radiation at constant intensity	Emit higher-intensity radiation
Used for smaller areas	Used for larger areas
Used more in clinics	Low pressure mercury discharge tubes with phosphor coating inside
Hot / Cold Quartz

Dilation of blood vessels due to ______ release

histamine

Skin erythema occurs after exposure to _____ or _____ after drug sensitization

UVB or UVA

Skid redness is due to _______ release

prostaglandin release

Delayed pigmentation of the skin

Tanning

In tanning, there is increase production and upward migration of _____________ and oxidation of __________

Increased production and upward migration of melanin granules and oxidation of premelanin

How does tanning affect UV penetration

decreased penetration

Thickening of superficial layer of skin (epidermis; stratum corneum)

Epidermal Hyperplasia

Thickening of the epidermis is due to __________

cell proliferation

Epidermal Hyperplasia occurs usually after _________ of exposure to UVR

after 72 hours

Purpose of UVR for vitamin D

Converts ingested provitamin D to active vitamin D

Practical Application for the Vitamin D benefits of UVR

indicated for Psoriasis

Desquamation

sloughing off dead skin cells

UVR vs IRR

UVR	IRR
Chemical Effect (non-thermal)	Physical effect (thermal)
No head	Absorbed as heat
Absorbed at 1-2 mm	Absorbed at 3mm
Luminous sources	Luminous and non-luminous
Delayed erythema (dark)	Immediate erythema (light)
Erythema lasts for several days	Erythema lasts for 20-30 minutes

Irradiance is AKA

Intensity or power density

Irradiance is measured by?

UV sensor on device

Unit of Irradiance

mW/cm²

Amount of energy delivered to skin for a single treatment

Dose per treatment; D mJ/cm² = I x T

Summation of all doses

Cumulative Dose (J/cm²)

Fitzpatrick Skin Phototype method

Recommended UV dosing based on skin phototype

Dose of UV radiation that will produce a barely detectable erythema about 8-24 hours after exposure

Minimal erythemal dose method

Degrees of Erythema

Dosage	Latent Period	Appearance	Duration
SED		No erythema
MED	6-12 hrs	Mild pink	<24 hrs
E1	6 hours	Definite pink; blanching	2 days
E2	3 hrs	very red; not blanching	3-5 days
E3	<2 hrs	‘angry’ red	7 days

Degrees of Erythema Effects

Dosage	Edema	Discomfort	Desquamation	Dose Multiplier
SED	no erythema
MED	x	x	x	1
E1	x	slight soreness	Powdery	2.5
E2	some	hot & painful	Thin sheets	5
E3	Blister	Very painful	Thick Sheets	10

Summary of Dosimetry (Dose, Frequency, BSA)

Dosage	Dose	Progression	Frequency	BSA
SED		12.5%	Daily	100%
MED	1	25%	Daily; every other day	50-100%
E1	2.5	50%	Every other day	<20%
E2	5	75%	2x/week	4%
E3	10	NA	1x/week	<25 cm²

Computation for intensity progression

For Cold Quartz (Kromayer lamp), the lamp is applied at least ______ away from the wound

1 inch

For Hot quartz lamp, the lamp is initially applied at ______ distance

60-80 cm

Distance is altered when _____________

duration has reached the maximum of 5 minutes

Narrow-band UVB is indicated for ?

• Subacute and chronic psoriasis, vitiligo

• MED or E1

Guidelines for application for Cystic Acne / Acne Vulgaris

• E1 for face, neck and chest

• E2 for back and shoulders

• UVR produces desquamation effect to stimulate growth of new healthy skin and provides antibiotic effects to destroy the infecting organisms

PUVA (Psoralen + UVA) is used for:

• Eczema

• Urticaria

• Cutaneous T-Cell Lymphoma

• Some photosensitive disorders

What type of UV is used for non-infected open wounds

UVC

Wound presents with meaty red color (good sign) = _______ tissue

granulation

Dose for infected wound with thin yellowish slough

E2 daily and unprogressed

Dose for decubitus ulcers affecting the epidermis/dermis

E1/E2

Dose for infected open wounds with black slough

E3 daily

Dose for infected wounds with definite green or yellow slough

E3 daily and unprogressed

Contraindications for UVR

• Over the eyes

• Skin cancer

• Pulmonary Tuberculosis

• Cardiac, kidney, or liver disease

• Systemic Lupus erythematosus

• Fever

• Taking birth control pills

Precautions for UVR

• Photosensitivity or Photoallergy

• Photosensitizing medications

• Recent x-ray therapy

• No dose of UV be done until the effects of the previous treatment have disappeared

Adverse Effects of UVR

• Burning

• Premature aging of skin

• Carcinogenesis

• Eye damage

UV overdose is counteracted by?

applying IRR for 20 mins every hour for 6-8 hours

Documentation for Overdose

• date

• lamp used

• distance

• exact area treated

• time

• reaction obtained

Common areas for MED testing

areas that are not usually exposed to the sun

• volar aspect of forearm, inner thigh

Steps in Determining Dosage

1. Determine the MED

2. Determine the dosage

   • For initial treatment; the computed dose will be used for the initial session

3. Progress as necessary

   • compute for the progressions; max of 5 mins