Low Level Laser Therapy LLLT Flashcards
What is LLLT
Therapeutic application of low output laser for the treatment of disease and injury
Laser light is a form of what energy ?
Electromagnetic energy
Where can I find laser light on the electromagnetic spectrum
Between Infrared and visible spectra
Is laser superficial/deep? Thermal/nonthermal?
Laser is a superficial and nonthermal agent ( too low to produce heat)
The term laser is an acronym for :
Light Amplification by Stimulated Emission of Radiation
What is light
Emission of electromagnetic waves made of photons traveling in space
Compared to other forms of light, what characteristics/properties make lasers different ?
Monochromatic
Collimated
Coherent
What is phototherapy
The use of lights, or photons for therapeutic purposes οΏΌ
Common lights used for therapy are:
IR and UV
Are lasers in the infrared band visible to the human eye?
No
Lasers are classified into 4 major classes:
What are they?
What were they classified based on ?
Class 1
Class 2
Class 3a
Class 3b
Class 4
(Based on power output + exposure time)
What is meant by hazards
The potential risk of the lasers causing biological damage to the skin or eye (retina)
Class 1, 2, and 3a lasers
They have low power outputs ( < 5 mW)
Are not used for therapeutic purposes
Class 3b
Power output ranging from 5 to 500 mW
Can cause eye damage but doesnβt affect skin
Class 4 lasers
Power output > 500 mW
Can cause eye AND skin damage
History (just read)
What are the two laser categories
- what do they require
- what is the power output
- what is it used for
What is meant by monochromaticity?
What is the therapeutic advantage?
all photons accounting for the laser light have a single wave length and thus a single color
Advantage: absorption can be targeted at specific wavelength-dependent photoreceptor molecules called chromophores, varied within soft tissue
What is collimation?
What is the therapeutic advantage?
The ability of a laser beam not to diverge or spread with distance (the photons move in a parallel fashion, concentrating the beam of light)
Advantage : ability to be focused on a very small target area.
What is coherence?
What are the types of coherence?
How is coherence lost?
What is the therapeutic advantage?
Photons that make up a laser light travel in phase in both time and space with one another.
Temporal and spatial coherence
Coherence is lost immediately after the light gets absorbed by the skin, due to scattering and refraction.
No therapeutic advantage
Properties of light compared to laser light
Laser devices have 3 basic physical components
- Lasing medium (active medium)
- Resonance chamber
- Power supply
What is a lasing medium?
Provide examples
The material used to emit a laser light for which the laser is named
It is gas, liquid, or solid with excitable atoms
Examples:
HeNe
GaAlAs (diode)
What is a resonance chamber?
What is it made up of?
Which side is the beam of laser light emitted through ?
The cavity within the laser device that contains the active medium, which is activated or lased leading to the production of a beam of laser light.
It is made up of a sealed glass tube , housing the active medium and has a fully-reflective mirror at one end, and a semi-reflective mirror at the other end.
The beam of laser light is emitted through the semi-reflective mirror
What is power supply used in laser devices?
An electrical current passing through the residence chamber that powers the laser and stimulates the active medium.
What is spontaneous emission of radiation?
When atoms get excited, their electrons jump to higher orbitals and are now unstable and will go back to their original orbital by releasing energy in the form of light
What are the laser types that are used?
- wavelength
- penetration depth
Red light laser (HeNe)
- gaseous laser
- visible red band ( 600 - 750 nm)
- penetration depth: 0.5 cm
Infrared-light laser (GaAs / GaAlAs)
- diode lasers
- IR band ( 750 nm to 1000 nm) or (750 nm to 1 mm)
- GaAs: 904 nm
- GaAlAs: 820 nm
- penetration depth: 1 cm
Process of laser light emission
First: activation of active medium by electrical current.
The process of moving atoms from their resting ground state to their excited state
Second: population inversion
The majority of atoms are in their excited state
Third: spontaneous emission
Emission of photon caused by spontaneous drop of an electron from its excited state to its ground state.
Fourth: stimulated emission
Fifth: amplification
The back-and-forth movements of incident and newly emitted photons through the active medium amplifies the process of stimulated emission .
Sixth: laser beam emission
Effects of LLLT
photo-biomodulation effect
Photo chemical mechanisms
What is Photo-biomodulation effect?
- photo-biostimulation
- photo-bioinhibition
- what does the photo-biomodulation effect depend on? Which law does it follow? What does the law state?
Biomodulation is the process of modulating the biochemical responses or functions of a cell (simulating or inhibiting)
Photo-biostimulation :
Increases the cellular function (increases cell metabolism)
Photo-bioinhibition:
Decrease the cellular function (decreases cell metabolism)
Photo-biomodulation is DOSAGE DEPENDENT
Arndt-Schultz Law :
- lower dosages = photo-biostimulation
- higher dosages = photo-bioinhibition
How does LLLT stimulate cell metabolism?
- photochemical effects
Photonic absorption
- Grotthus-Draper Law: for photobiostimulation to occur, photonic energy must first be absorbed by the exposed soft tissue.
Chromophores :
Transfer of energy from a photon to a photon except your molecules within the cells called chromophores (color loving)
Ex: melanin, hemoglobin, retinal rhodopsin
Penetration depth
- absorption
- scattering
Penetration depth of laser light depends on:
Absorption:
- Greater in superficial tissue
- inversely related to penetration depth
- HeNe (red laser light) is more superficial than IR
Scattering :
- Wavelength dependent
( short wavelength = more scattering)
( longer wavelength = less scattering)
Which laser light has higher absorption and less scattering
Infrared laser (904-820 nm) > Red laser (632-694)
Due to having longer wavelength
Penetration depth value
Physiological effects of LLLT
Therapeutic benefits
What is power output (P) ?
Unit ?
How to convert units ?
Rate of energy delivered
Watts or Joule/sec
( 1 watt = 1 J/sec)
Commonly expressed in mw
(She says to go from Watt to mW , multiply Watt by 0.001, but that looks wrong)
What is power density (Pd) ?
Unit?
The power delivered per diodeβs beam area measured in cmΒ²
Unit: mW/cmΒ²
What is energy density or dosage (Ed)
Unit?
Formula?
The energy delivered per diodes beam area, multiplied by the time of radiation
J/cmΒ²
Pd x Time of irradiation
Power/area x time
What is dose per diode (Dd)?
Units ?
Formula ?
The amount of laser energy delivered to the tissue by each diode
Joules
Power of diode (J/s) x Time of irradiation (sec)
What is dose tissue (Dt) ?
Units?
Formula
The total amount of laser energy delivered to the exposed tissue
Joules
The sum of all the doses per diode (Dd) x number of points of application during a single treatment session
Formula to calculate time of irradiation (sec)
Time = (Ed x Area)/ Power
Pulse repetition rate
Expressed in hertz Hz
2-10 thousand Hz
Modes of emission of laser
Continuous mode
Pulsed mode
Dosage protocol for biostimulation
1 - 4 J/cm Β²
Stimulates growth and healing
Dosage protocol for bioinhibition
5 - 8 J/cmΒ²
Inhibits excessive scar tissue and destroys bacteria
Energy density for ACUTE and CHRONIC conditions
Lower energy density ( 0.05 to 0.5 J/cmΒ² ) - ACUTE
Higher dosage (0.5 to 3 J/cmΒ² ) - CHRONIC
Types of applicators of LLLT
Single diode
Multiple diode (cluster)
Class 3B lasers require both the therapist and patient to wear what protective gear
Eye protection goggles
(Filter wavelength must match photonics wavelength generated by laser device)
Application methods
- Point by point.
- Contact
- Noncontact (2 - 4 mm)
- Grid application : mapping the treated surface area with 1cmΒ² squares - Scanning technique.
- Wound treatment
General contraindications
Local contraindications
Adverse side effects
Transient tingling
Mild erythema
Burning sensation
Eye damage
Skin rash
Increased pain and numbness
Which modality is more effective with LLLT: hot pack, or cold pack?
Hot pack is more effective due to increase circulation and increase hemoglobin
