Light Modalities

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Light Modalities Chapter 19

Transcript of Light Modalities

Page 1: Light Modalities

Light Modalities

Chapter 19

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Description

Light modalities are found on the electromagnetic spectrum Most abundant form of

energy in the universe

Drying superficial tissues or via superficial photochemical effects

Some mild superficial thermal effects

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Types of Therapeutic Lamps

Infrared Superficial dry heat

Ultraviolet Heats the body’s tissues for either tissue

destruction or therapeutic effects Laser

Combination of homogenous ultraviolet and/or infrared energy

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Infrared Lamp

Used to dry seeping open wounds or sedate superficial sensory nerves

Radiant modality: An electrical current passes through a carbon or tungsten filament 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

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Types of Infrared Lamps

Near-Infrared 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

Light bulb Some energy is reflected by the surface of the skin

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Types of Infrared Lamps

Far-Infrared Nonluminous Infrared

Radiation Wavelength: 1,500 to

12,500 nm Thermal Effects: < 2mm

Less penetrating than Near-Infrared Skin feels warmer

Energy formed by metal coil i.e. electric stove or space

heater Invisible to human eye

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Effects of Infrared Lamps

Constant, dry heat to assist with superficial tissue Dermatological conditions Increase cell metabolism Blood flow Muscle Relaxation

Contraindications Any conditions in which other forms of

superficial heat are contraindicated

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Clinical Application

Turn On and warm if necessary Treatment Duration: 20 to 30 minutes Intensity: adjust wattage or distance of lamp

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

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Ultraviolet Therapy

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

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Types of UV UV-A

AKA: near UV Effect:

Erythema without pigmentation UV-B

AKA: middle UV Effects:

Erythema without pigmentation Formation of vitamin D Skin tanning (blister/burn)

UV-C AKA: far UV Effects:

Kills bacteria Formation of vitamin D Skin tanning

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Types of UV Lamps

‘Hot’ UV Lamps 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 High Volt (3000V) Low-Amp (15mA) Energy is cooler than ‘Hot’ and produce UV-C

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Biophysical Effects

Energy absorbed at a depth between 0.20 to 0.22 mm

Damages cell proteins, DNA, & RNA to initiate local inflammatory responses

Effects: Vitamin D synthesis Enhances melanin production Thickens epidermis Superficial vasodilatation Bactericide

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Effects of UV Lamps

Wound Healing Activates inflammatory response Use: Cold Lamps at intensity of E3

Treat Skin Disorders i.e. psoriasis Exfoliates tissue and damage DNA that produces

the excess skin growth associated with psoriasis Use: UV-B

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UV Contraindications

Sunlight sensitivity Fair skin (precaution) Medications or food that increase sunlight

sensitivity Examples:

Tetracycline Shellfish

Hyperthyroidism

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UV Dosage

Determined by Minimal Erythema Dose Least amount of UV exposure time to produce

redness within 1-6 hrs and disappear within 24 hours “Hot” Lamps

Determined by each patient and each lamp Standard distance = 30 in., not closer than 15 in.

“Cold” Lamps Standard MED value 12-15 seconds at a distance = 1 in.

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Determining MED for UV Lamp

Cardboard Test Strips 1. 6 different shapes cut

out 2. Use to cover shapes

UV Lamp 30 in. away

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MED (Cont.)

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

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UV Treatment Dosage SED

No erythema MED

Smallest dose that produces erythema within 1-6 hr E1

Erythema lasts for 1-3 days, some scaling of skin present, approximately 2.5x MED

E2 Erythema with edema, peeling, and pigmentation, approximately

5x MED E3

Severe erythema and burning, blistering, peeling, edema, approximately, 10x MED

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Clinical Application

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

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Adjusting the Treatment Dose

Biophysical changes occur with light exposure causing changes in treatment

Duration 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

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Therapeutic Lasers

L=Light A=Amplification by S=Stimulated E=Emission of R=Radiation Classified by the FDA’s Center for Devices

and Radiological Health

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Types of Lasers High-Power Laser

“Hot Laser” Effect:

Causes thermal changes in tissues (cause tissues to be destroyed, evaporated, or dehydrated)

Uses: Surgery Capsular shrinkage Wrinkle and tattoo removal

Low-Power Laser “Cold Laser” Effect

Causes photochemical changes in tissue Uses:

Wound healing Arthritis Burn care

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Production of Laser Energy

Lasers are referred to by the type of active medium (gas, liquid, solid) 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

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Effects of Lasers

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

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Wound Healing

Superficial wounds 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

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Pain Reduction

Decrease acute and chronic pain Reduce the rate and velocity of sensory

nerve impulses Similar to cryotherapy but without thermal

changes

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Fracture Healing

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