Transcript Light Modalities

Light Modalities
Chapter 19
Description
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Light modalities are
found on the
electromagnetic
spectrum
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Most abundant form of
energy in the universe
Drying superficial
tissues or via superficial
photochemical effects
Some mild superficial
thermal effects
Types of Therapeutic Lamps
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Infrared
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Ultraviolet
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Superficial dry heat
Heats the body’s tissues for either tissue
destruction or therapeutic effects
Laser
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Combination of homogenous ultraviolet and/or
infrared energy
Infrared Lamp
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Used to dry seeping open wounds or sedate
superficial sensory nerves
Radiant modality: An electrical current passes
through a carbon or tungsten filament
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Intensity controlled by adjusting current flow or distance
between lamp and tissue
Constant temperature, increased risk of burns
Heating skin depends on the amount of radiation absorbed
 Pigmented, darker skin will absorb more energy and will
heat more rapidly than lighter skin
Types of Infrared Lamps
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Near-Infrared
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Luminous Infrared Lamp
Wavelength: 780 to 1,500 nm (near visible light)
Thermal Effects: 5 to 10 mm deep
Energy formed by carbon and tungsten filament
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Light bulb
Some energy is reflected by the surface of the skin
Types of Infrared Lamps
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Far-Infrared
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Nonluminous Infrared
Radiation
Wavelength: 1,500 to
12,500 nm
Thermal Effects: < 2mm
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Less penetrating than
Near-Infrared
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Skin feels warmer
Energy formed by metal coil
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i.e. electric stove or space
heater
Invisible to human eye
Effects of Infrared Lamps
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Constant, dry heat to assist with superficial
tissue
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Dermatological conditions
Increase cell metabolism
Blood flow
Muscle Relaxation
Contraindications
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Any conditions in which other forms of
superficial heat are contraindicated
Clinical Application
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Turn On and warm if necessary
Treatment Duration: 20 to 30 minutes
Intensity: adjust wattage or distance of lamp
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Luminous = 24 inches
Nonluminous = 32 inches
Inverse Square Law
Cosine Law
Clean sweat and dirt, remove jewelry, and fit
infrared goggles (if applicable) for patient
Ultraviolet Therapy
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Used to produce photochemical reactions in
the skin
Wavelength: 180 to 400 nm
3 UV bands (A, B, and C) produce unique
effects
Ultraviolet A & B Lamp
Ultraviolet C Lamp
Types of UV
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UV-A
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AKA: near UV
Effect:
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UV-B
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AKA: middle UV
Effects:
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Erythema without pigmentation
Erythema without pigmentation
Formation of vitamin D
Skin tanning (blister/burn)
UV-C
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AKA: far UV
Effects:
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Kills bacteria
Formation of vitamin D
Skin tanning
Types of UV Lamps
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‘Hot’ UV Lamps
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Low Volt (30-110V) High-Amp (5A)
Electrical current passes through tube, argon gas
heats, vaporizing and polarizing mercury to
produce UV light in ALL 3 bands and visible violet
light
‘Cold’ UV Lamps
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High Volt (3000V) Low-Amp (15mA)
Energy is cooler than ‘Hot’ and produce UV-C
Biophysical Effects
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Energy absorbed at a depth between 0.20 to 0.22
mm
Damages cell proteins, DNA, & RNA to initiate local
inflammatory responses
Effects:
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Vitamin D synthesis
Enhances melanin production
Thickens epidermis
Superficial vasodilatation
Bactericide
Effects of UV Lamps
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Wound Healing
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Activates inflammatory response
Use: Cold Lamps at intensity of E3
Treat Skin Disorders
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i.e. psoriasis
Exfoliates tissue and damage DNA that produces
the excess skin growth associated with psoriasis
Use: UV-B
UV Contraindications
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Sunlight sensitivity
Fair skin (precaution)
Medications or food that increase sunlight
sensitivity
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Examples:
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Tetracycline
Shellfish
Hyperthyroidism
UV Dosage
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Determined by Minimal Erythema Dose
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“Hot” Lamps
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Least amount of UV exposure time to produce
redness within 1-6 hrs and disappear within 24
hours
Determined by each patient and each lamp
Standard distance = 30 in., not closer than 15 in.
“Cold” Lamps
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Standard MED value
12-15 seconds at a distance = 1 in.
Determining MED for UV Lamp
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Cardboard Test Strips
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1. 6 different shapes cut
out
2. Use to cover shapes
UV Lamp 30 in. away
MED (Cont.)
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Expose 1 cut out, open the
shutters for 30- sec.,
expose the 2nd cut out and
leave the 1st uncover for
the 30-sec.
Repeat the steps above for
the remaining 4 cut outs,
but expose them at 15-sec
intervals
Instruct patient to check
area every hour and record
changes
UV Treatment Dosage
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SED
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MED
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Erythema lasts for 1-3 days, some scaling of skin present,
approximately 2.5x MED
E2
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Smallest dose that produces erythema within 1-6 hr
E1
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No erythema
Erythema with edema, peeling, and pigmentation, approximately
5x MED
E3
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Severe erythema and burning, blistering, peeling, edema,
approximately, 10x MED
Clinical Application
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Calculate treatment dose and duration
Clean area and remove jewelry
Cover skin not being treated (sunscreen if
applicable)
Fit UV-resistant goggles to patient and clinician
Position lamp at right angle using the correct
distance and duration for each type of lamp
Clean machine and check periodically for
maintenance of bulbs
Adjusting the Treatment Dose
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Biophysical changes occur with light
exposure causing changes in treatment
Duration
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30 to 50% increase for each subsequent
treatment
If 3 to 5 minutes, then distance is reduced
5 to 10 sec is decreased when missing a
treatment
Be aware of patients skin color and the lamps
distance, duration, and angle
Therapeutic Lasers
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L=Light
A=Amplification by
S=Stimulated
E=Emission of
R=Radiation
Classified by the FDA’s Center for Devices
and Radiological Health
Types of Lasers
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High-Power Laser
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“Hot Laser”
Effect:
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Uses:
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Causes thermal changes in tissues (cause tissues to be destroyed,
evaporated, or dehydrated)
Surgery
Capsular shrinkage
Wrinkle and tattoo removal
Low-Power Laser
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“Cold Laser”
Effect
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Causes photochemical changes in tissue
Uses:
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Wound healing
Arthritis
Burn care
Production of Laser Energy
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Lasers are referred to by the type of active
medium (gas, liquid, solid)
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HeNe: visible red light penetrating 0.8 to 15mm
GaAs: invisible penetrating up to 2 cm
Energy is introduced into the active medium
An orbiting electron briefly elevates into a
higher or ‘excited’ state
The electron spontaneously returns and
releases another photon
Effects of Lasers
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Photons are absorbed by tissues to alter
molecular-level activity
Theorized to affect pain-producing tissue
(muscle spasm), by increasing ATP synthesis
that increases cell metabolism and
encourages the release of free radicals
Wound Healing
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Superficial wounds
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Ulcers, surgical insicison, burns
Lasers alter cell membrane permeability and
increase in fibroblast, lymphocyte, and
macrophage activity occurs
Blood and lymph improve to promote the
growth of granulation tissue
Increase collagen and tensile strength of
healing wounds
Pain Reduction
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Decrease acute and chronic pain
Reduce the rate and velocity of sensory
nerve impulses
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Similar to cryotherapy but without thermal
changes
Fracture Healing
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May enhance fracture
healing and bone
remodeling by increasing
capillary formation, calcium
deposition, increase callus
formation, and reducing
hematomas
Photons striking the tissue
create acoustic waves that
affect bone healing similar
to ultrasonic bone growth
stimulators