Download LASER

LASERS & Lights
By
Beverly Nelson
Outline of Presentation
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Defining LASER
Production of laser
Classification of Laser
Method of application
Biological effects
Clinical indications
Precautions & contraindications
What is LASER ?
• Acronym for Light Amplification of
Stimulated Emissions of Radiation
• Relatively new modality which is still
undergoing research
Physics of LASER production
• Please read handout provided
• Laser light contains electromagnetic energy
Properties of LASER
• Coherence• Monochromaticity
• Collimination
Classification of Lasers
• According to the nature of material placed
between the two reflecting surfaces
• Many types of lasers, each with specific
wavelength and characteristics
Classification cont’d
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Crystal
Gas
Glass
Semiconductor or diode
chemical
Classification cont’d
• Classification according to high or low power
• Depends on the intensity of energy they
deliver
Classification cont’d
• High power lasers or Hot Lasers generate
thermal response
• Used in the Medical Realms- surgical cutting
Low level power laser
• Used as a rehabilitation intervention for pain
management and wound healing.
• Is relatively new area in medicine (20 – 25 yrs)
• Maximal output of power < 1 milliWatt
Low lever Laser
• Work by producing photochemical rather
than thermal effect
Laser light used in Rehab
• There are two types of Laser lights used in
rehabilitation
• Helium Neon –HeNe
• Gallium Arsenide -- GaAs
Helium Neon
• Gas laser
• Uses a mixture of Helium and Neon in a
pressurised tube
• Creates Laser in the Red portion of the
electromagnetic spectrum
Has a wavelength of 632.8nm
Depth of penetration
• Absorbed in the superficial tissues - 2- 5 mm
of soft tissue
• Indirect effect at 8 – 10 mm depth of soft
tissue
Laser output is affected by
• Care of the equipment
• The number of operating hours
• Quality of fibreoptics used
Gallium Arsenide Laser
• Utilise a diode to produce an infrared (
invisible) Laser
• Wavelength of 904nm 3 – longer wavelength
than HeNe
• Absorbed at depths of 1 – 2 cm
• Indirect effect of up to 5cm
GaAs Laser
• Has a peak power of 2watts which is delivered
in a pulsed mode to decrease the thermal
effect
• Greater potential for treatment of deeper soft
tissue
Method of application
• There are three methods of application:
• Gridding
• Scanning
• Wanding
Biological effects
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Promotes ATP production
Promotes collagen production
Modulates inflammation
Inhibits bacterial growth
Promotes vasodilatation- microcirculation
Alters nerve conduction velocity
Effects of Laser
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Facilitate wound healing
Reduction of pain
Increase tensile strength of star
Decrease in inflammation
Bone response
Clinical indication
• Tissue healing :chronic and acute wounds( can
promote tissue repair but more high quality
studies needed) accelerated healing
• Arthritis
• Postmasectomy Lymphedema (more evidence
needed)
Clinical indication cont’d
• May reduce pain in patients with
neuromusculoskeletal conditions .
• Eg back pain, neck pain, trigger points
• Pain management
Contraindications
• Direct irradiation of the eyes
• Malignancy
• Ares recently exposed to radiotherapy
• Haemorrhaging Regions
Precautions
• Low back or abdomen during pregnancy
• Epiphyseal plates in children
• Impaired sensation or mentation
Parameters for the use of lasers
• Type of diode
• Wavelength
• Power
• Energy density
Type of Diode
• LED – light emitting diode- semiconductor diode
that produces low power light in a range of
frequencies
• SLD- supraluminous diode- semiconductor that
produces high power light in a narrow frequency
range
• Laser diode – semiconductor diode and optics
that produce laser light
Wavelength
• Laser light applicators produce/output light in
the visible or near visible wavelength range of
the electromagnetic spectrum
• IR (700 – 1100nm)- longer wavelength and
penetrates deeper tissue up to 30 to 40 mm
• Red light(600 -900nm)- short wavelength and
suitable for treating superficial tissue at a
depth of 5- 10mm
Power
• Light applicator is measured in milliwatts
• Laser for therapy are power more than 5mW
and less than 500mW
• Low power light applicators require more time
to deliver the same amount of energy as high
power light applicators
Energy Density
• Lower energy density recommended for acute
and superficial conditions
• High energy density recommended for chronic
and deeper conditions
Documentation
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Type of Diode- LD, LED,LED ?
Wavelength (nm)
Power (mV)
Area of body to be treated
Energy Density
Suggested readings
• Physical Agents in Rehabilitation by Michelle
Cameron
• Therapeutic Modalities in Rehabilitation by
William E.Prentice