UVR Flashcards
bands of UVR
UVA,B,C
among three bands of UVR which has the longest wavelength
UVA
UVA wavelength
320-400 nm
UVB wavelength
290-320 nm
UVC wavelength
<100-290 nm
other name for UVA, B and C
A: long wave; near
B: middle wave
C: short wave, far
Frequency: ranges from
1.65 x1015 to 7.5 x 1014
Wavelength: shorter than –, longer than –
visible, x-ray
use of UVA
blacklight
use of UVB
skin erythema; sunburn
UVC use
germicidal and bacterial purposes
Method of transmission:
radiation via phototherapy
UV is not visible to us but we can feel it
Photochemical effect
Possibilities:
Reflected, refracted, absorbed
Absorbed within 1-2mm (0.22) mm of human skin
80-90% absorbed in the dermis
UV produces heat?
no
UV is both –ing and –ing
UV is both ionizing and non-ionizing
what can happen if wrong dosage is applied
Cutaneous malignant melanoma
Basal cell carcinoma
Squamous cell carcinoma
Factors affecting penetration
Intensity => directly related Wavelength => directly related Power of radiation source => direct Exposure duration => direct Distance of radiation => inverse Frequency => inverse Size => inverse Thickness => inverse Pigmentation of skin => inverse
equipment
Mercury arc
Fluorescent
Mercury arc lamps:
Small Emit radiation at constant intensity Used for smaller areas Types: Hot quartz Cold quartz
Fluorescent lamps
Long
Emit higher-intensity radiation
Used for larger areas
Low pressure mercury discharge tubes with phosphor coating inside (theraktin)
hot quartz
burner w argon gas and mercury
high pressure and temp
c erythema and pigmentation
applied >15 inches form area
no need for warm up
cold quarts
cold quartz with mercury (ionized vapor)
dec pressure and temp
minimal erythema and no pigmentation
applied at close proximity
needs 5 min warm up
physiological effects
erythema production delayed pigmentation of skin thickening of superficial layer of skin vit d synthesis bactericidal effect
Erythema production
Vasodilation of vessels
Happens because of histamine and prostaglandin release
Exposure to UVB or UVA after drug sensitization
Practical application: proper dosage
Delayed pigmentation of skin
Production and upward migration of melanin
Oxidation of pre melanin
Tanning = less penetration
Practical app: examine skin phototype of patients
Thickening of superficial layer of skin
Thickening of epidermis due to cell proliferation
72 hrs after exposure to UVR
Practical app: progressive higher dose for thicker skin
Vitamin D synthesis
Converts inactive provitamin D to become active vit D
Activates inactive vit D
Effective treatment for psoriasis
Practical application: for psoriasis
Bactericidal effect
UVC = bactericidal affect
Promotes wound healing
Desquamation => slough off dead skin cells
Practical app: bactericidal effect in open wounds
irradiance (I)
intensity or power density
measured by uv sensor on device
mw/cm2
dose per treatment time (Dt) =
I X T
cumulative dose (Dc) =
sum of all Dt
Bunsen-roscoe law/reciprocity law
inverse relationship of irradiance and exposure time
method based on skin color
fitzpatrick skin phototype method
type 1
lighter white
burns easily and never tans
BBUVB initial: 20
BBUVB progression: 5
NBUVB initial: 130
NBUVB progression: 15
type 2
darker white
burns easily tans minimally
BBUVB initial: 25
BBUVB progression: 10
NBUVB initial: 220
NBUVB progression: 25
type 3
light brown
burns moderately; tans gradually
BBUVB initial: 30
BBUVB progression: 15
NBUVB initial: 260
NBUVB progression: 40
type 4
moderate brown
burns minimally; tans well
BBUVB initial: 40
BBUVB progression: 20
NBUVB initial: 330
NBUVB progression: 45
type 5
dark brown
burns rarely; tans profusely
BBUVB initial: 50
BBUVB progression: 25
NBUVB initial: 350
NBUVB progression: 60
type 6
black
never burns; intense tanning
BBUVB initial: 60
BBUVB progression: 30
NBUVB initial: 400
NBUVB progression: 65
frequency of fitzpatrick phototype method
3-5x/week
minimal erythemal dose method levels
suberythemal minimal erythemal first degree second degree third degree
SED
no erythema
progression: 12.5%
frequency: daily
BSA: 100%
MED
latency period: 6-12 hrs appearance: mild pink duration: <24 hrs dose: 1 progression: 25% frequency: daily; every other day BSA: 50-100%
E1
latency period: 6 hrs appearance: definite pink; blanching duration: 2 days discomfort: slight soreness desquamation: powdery dose: 2.5 progression: 50% frequency: every other day BSA: <20%
E2
latency period: 3 hrs appearance: very red; not blanching duration: 3-5 days edema: some discomfort: hot and painful desquamation: thin sheets dose: 5 progression: 75% frequency: 2x/week BSA: 4%
E3
latency period: <2 hrs appearance: angry red duration: 7 days edema: blister discomfort: very painful desquamation: thick sheets dose: 10 progression: NA frequency: 1x/week BSA: <25 cm2
contraindications
Over eyes Skin cancer Pulmonary tuberculosis Cardiac kidney liver disease Systemic lupus erythematosus Fever Taking birth control pills
Precautions
Photosensitivity or photo allergy Determine what type of allergic reaction Itchy, stop treatment Photosensitizing medications Psoralen: good agent Sulphonamides and tetracyclines - antibiotic Griseofulvin - antifungal Phenothiazine - tranquilizer Chlorothiazide - diuretic Recent x-ray No dose of UV should be done until effects of previous treatment have disappeared (3-6 months)
adverse effects
Burn effects Premature aging of skin (actinic damage) Carcinogenesis UV overdose Counteracted with IRR for 20 mins every hour for 6-8 hours
documentation
date, lamp used, distance, exact area, position, time, reaction obtained
subacute and chronic psoriasis
Decreases DNA synthesis Lower proliferation of cells Narrow-band UVB MED or E1 Also for vitiligo PUVA (psoralen + UVA) Usually E1 is used E2 for heels and elbows
Cystic acne/acne vulgaris
E1 for face, neck, chest
E2 for back and shoulders
PUVA is used for
Eczema
Urticaria
Cutaneous t cell lymphoma
Photosensitive disorders
Non-infected wounds
Surgical incisions, ulcers
Use UVC (can still use UVB)
Granulation tissue (bright red color means healing well) => no treatment necessary
If insisted by doc or pt: suberythema or MED, no progression applied
Decubitus ulcers affecting epidermis/dermis
Can use E1/E2
E1 for initial treatment
Progress to E2 when pt reacts well
Surrounding skin
MED daily
Infected wounds
Destroys and removes slough
Strengthen growth of granulation tissue
Thin yellowish slough => E2 daily and unprogressed
Definite green and yellow slough => E3 daily and unprogressed
Black slough => E3 daily
Reassess when black is gone
Surrounding skin => MED daily
