Light TherapyLight Therapy

ESAT 3640Therapeutic Modalities

ESAT 3640Therapeutic Modalities

What is Light Therapy?What is Light Therapy?

Definition - The application of

light by a variety of devices for a variety of therapeutic purposes.

Definition - The application of

light by a variety of devices for a variety of therapeutic purposes.

TypesLasersLEDsSLDsInfrared lampsUV lampsDiachronic lampsFluorescent lampsVery bright light

bulbs

TypesLasersLEDsSLDsInfrared lampsUV lampsDiachronic lampsFluorescent lampsVery bright light

bulbs

Laser vs. NonlasersLaser vs. Nonlasers

Light is light right?Maybe not

Both produce light wavesSpecific wavelengthsEnergy is produced differently

Can’t say issue is laser vs. LEDCoherent vs. noncoherent light

Light is light right?Maybe not

Both produce light wavesSpecific wavelengthsEnergy is produced differently

Can’t say issue is laser vs. LEDCoherent vs. noncoherent light

Characteristics of LasersCharacteristics of Lasers

To produce laser radiation, you must have:Energy sourceMechanical structureLasing medium

GasLiquidCrystalChemicalSemiconductor (LED)

To produce laser radiation, you must have:Energy sourceMechanical structureLasing medium

GasLiquidCrystalChemicalSemiconductor (LED)

Characteristics ContinuedCharacteristics Continued

Laser light isMonophasicMonochromaticCoherentnondivergent

Laser light isMonophasicMonochromaticCoherentnondivergent

More Terms Associated With Lasers

More Terms Associated With Lasers

LightAmplifyStimulateEmissionRadiation

LightAmplifyStimulateEmissionRadiation

Electromagnetic energy

FrequencyVisible lightFixed Phase

Electromagnetic energy

FrequencyVisible lightFixed Phase

Nature of LightNature of Light

Light is both a wave and a particleTravels from one point to another in

form of waveAbsorbed or emitted by atom it acts

like a particleParticles = photons

Amount of energy in photon is a function of its wavelength or frequency

Light is both a wave and a particleTravels from one point to another in

form of waveAbsorbed or emitted by atom it acts

like a particleParticles = photons

Amount of energy in photon is a function of its wavelength or frequency

Laser Energy ProductionLaser Energy Production

Amplifying chamber

resonating cavity

Lasing medium External energy

source Pair of mirrors

Amplifying chamber

resonating cavity

Lasing medium External energy

source Pair of mirrors

Production of Laser EnergyProduction of Laser Energy

Energy applied to lasing material

Absorbed energy excites atoms Higher energy orbits Unstable state Electrons return to

normal state Absorbed energy

released as a photon

Energy applied to lasing material

Absorbed energy excites atoms Higher energy orbits Unstable state Electrons return to

normal state Absorbed energy

released as a photon

What Determines Its Effect?

What Determines Its Effect?

Energy levelTherapeutic lasers emit low level

energy< 500mW

Often referred to aslow-level lasersCold lasersSoft lasers

Energy levelTherapeutic lasers emit low level

energy< 500mW

Often referred to aslow-level lasersCold lasersSoft lasers

Laser ClassificationLaser Classification

Classified by lasing medium or safety

Gas lasersDiode (semiconductor) lasersDye lasersSolid-state lasersExcimer lasers

Classified by lasing medium or safety

Gas lasersDiode (semiconductor) lasersDye lasersSolid-state lasersExcimer lasers

Types of LasersTypes of Lasers

Type Medium Wavelength (nm)

Safety Classification

Gas HeNe 633 I-IV

Gas CO2 10,600 IIIb-IV

Gas Argon 488-514 IV

Diode AlGaAs 600-1000 IIIb

Dye Tunable dye 577 IV

Solid State Ruby 694 IV

Solid State HdYag 1060 IV

Excimer Dimer 351 IV

Safety ClassificationsSafety ClassificationsClass Power

(mW)Visibility

Safety Concerns

I < 0.5 Either None

II < 1 Visible Safe for momentary viewing

IIIa < 5 Either Photochemical effect

IIIb < 500 Either Photobiomodulation, no photothermal effect, no harm to skin or clothing, possible damage to eye

IV > 500 Either Photothermal effect, harmful to skin, eyes, & clothing; use with extreme caution

Characteristics of LEDs and SLDs

Characteristics of LEDs and SLDs

LED - Light-emitting diodeSLD - Super-luminous diode

Semiconductor diodes that emit visible light when electric current passes through them

Semiconductor medium impregnated w/ impurities to create a structure called a p-n junction

LED - Light-emitting diodeSLD - Super-luminous diode

Semiconductor diodes that emit visible light when electric current passes through them

Semiconductor medium impregnated w/ impurities to create a structure called a p-n junction

P-N JunctionP-N Junction

One side (+) charge One side (-) charge Current flows in 1

directions Current blocked in

other direction leading to photon release = light

Wavelength depends on doping material Determines color of light

One side (+) charge One side (-) charge Current flows in 1

directions Current blocked in

other direction leading to photon release = light

Wavelength depends on doping material Determines color of light

LEDs and SLDsLEDs and SLDs

MonochromaticNot coherent

More scatterLess light strikes target tissues

Less energy imparted to tissues

MonochromaticNot coherent

More scatterLess light strikes target tissues

Less energy imparted to tissues

Lasers vs. Diode DevicesLasers vs. Diode Devices

Both use semiconductorsp-n junction of diode device emits

energy directly to patientLaser - emission from diode is

further processed to stimulate additional photonsBeam is coherent and contains more

photons per area

Both use semiconductorsp-n junction of diode device emits

energy directly to patientLaser - emission from diode is

further processed to stimulate additional photonsBeam is coherent and contains more

photons per area

Effect of Light Therapy on Tissue

Effect of Light Therapy on Tissue

PhotobiomodulationMechanisms of action

Excitation of electron bondsExcitation of atoms to higher level of

oscillationRotational changes of atoms

PhotobiomodulationMechanisms of action

Excitation of electron bondsExcitation of atoms to higher level of

oscillationRotational changes of atoms

Effects ContinuedEffects ContinuedTissue healing

Inflammatory phaseRepair phaseRemodeling phase

Pain reliefIncreased serotoninDecreased cholinergic releaseInhibition of prostacyclinIncreased sensory nerve transmission timeIncreased CNS pain perception thresholdPlacebo effect

Tissue healingInflammatory phaseRepair phaseRemodeling phase

Pain reliefIncreased serotoninDecreased cholinergic releaseInhibition of prostacyclinIncreased sensory nerve transmission timeIncreased CNS pain perception thresholdPlacebo effect

Delivery TechniqueDelivery Technique

Single probe1 wavelength

Cluster probeMultiple wavelengths

Grid applicationOne location at a time

ScanningMove like US

Single probe1 wavelength

Cluster probeMultiple wavelengths

Grid applicationOne location at a time

ScanningMove like US

Dosage and DurationDosage and Duration

Dosage (J/cm2) = (avg. power (mW) x Tx time (min)) Tx area (cm2)

Average Power = pulse rate (Hz) x peak power x pulse width (sec)

Tx time = (dosage x Tx area) power

Dosage (J/cm2) = (avg. power (mW) x Tx time (min)) Tx area (cm2)

Average Power = pulse rate (Hz) x peak power x pulse width (sec)

Tx time = (dosage x Tx area) power

Treatment ParametersTreatment ParametersCondition Dosage range Notes

Superficial wounds 0.5-4.0 J/cm2 Increase dosage as wound bed develops

Trigger points 8 J/cm2 Each site at 1 J

Nerve root 8-24 J/cm2 1-3 J/point

Tendinitis 1-3 J/point

Capsulitis 1 J/point

Epicondylitis 2-3 J/point

Muscle strain 1-2 J/point

Patellofemoral problems 1-2 J/point

Ligament sprain 2-4 J/point

Plantar fasciitis 1-3 J/point

Treatment ParametersTreatment Parameters

Acute (J) Chronic (J)

Condition Per point Total Per Point Total

Strain 3-4 25-35 5-6 35-45

Tendinitis 3-6 24-30 5-8 35-45

Sprain 3-4 25-30 5-6 35-45

Stress fx 7-8 25-30 8-10 35-40

Open wounds 0.5-1.5 * 1-4 *

Trigger points 1.0 J 1.0 J 1.0 J 1.0 J

* Depends on wound size

ContraindicationsContraindications Eyes Over areas of steroid injection in the past 2-3 weeks Possible cancerous tissues Over the anterior neck, chest or cardiac region Directly over open wounds Over areas of active hemorrhage Over sympathetic ganglia Pregnancy Areas that may mask progressive pathology Over or near bone growth centers Ischemic tissues

Eyes Over areas of steroid injection in the past 2-3 weeks Possible cancerous tissues Over the anterior neck, chest or cardiac region Directly over open wounds Over areas of active hemorrhage Over sympathetic ganglia Pregnancy Areas that may mask progressive pathology Over or near bone growth centers Ischemic tissues