LASER Flashcards
What does LASER stand for?
Light Amplification by Stimulated Emission of Radiation
What is a LASER?
An electromagnetic modality with a wavelength in the ultraviolet, visible light and infrared spectrum
What range are the wavelengths?
Between 400 nm (ultraviolet) and 70 nm (infrared)
What are hot LASERS’s?
Emit an energy measured in watts that result in a thermal effect in the tissue
What are hot LASER’s used for?
Can cause tissue destruction and are used for surgical purposes (ex. eye surgery)
What are cold LASER’s?
Emit an energy measured in milli-watts that have no thermal effects
What are cold LASER’s used for?
To stimulate a photochemical effect in the cell
What is low level laser therapy?
The accepted terminology for the use of therapeutic LASER technology
What is polychromatic?
A combination of light waves of varying lengths and colour combined to result in white light
What does a prism do?
Separates light waves of differing lengths resulting in light beams of varying colours (ROY G BIV)
What are some LASER beam characteristics?
- Monochromatic
- Coherent
- Collimated
- Low power (measured in milli-watts)
- High density (focused light beam)
What are the different types of beam shapes?
- Collimated
- Diverging
- Converging
What are some characteristics of light?
- Dual nature: both a wave and a particle
- Light energy is transmitted through space as particles that contain tiny ‘energy packets’ called photons
- Each photon has a unique wavelength and frequency
- If a photon of adequate energy level collides with an electron of an atom it causes the atom to be in an excited state
What is the physics of LASER?
- Energy stimulation is at the atomic level of a cell
- Causes the electron to jump to a higher orbit ‘energizing’ the atom
- The atom wants to return to its normal state and releases the energy in the form of a photon
- All the photons are all identical in wavelength
What is spontaneous emissions?
Atoms release energy photons randomly in different orders and different directions; naturally occurring
What is stimulates emissions?
Occurs when a photon of specific energy is introduced and absorbed by the atom
How does stimulated emission occur?
An environment must exist with unlimited excited atoms; this is called population inversion
What is a LASER generator?
Comprised of a tube with mirrors at either end, one being semi-permeable
What are some different types of lasing mediums between the mirrors?
- Gas: HeNE (helium/neon)
- Semiconductor: GaAs (galium arsenide)
- Synthetic ruby (crystal lasers)
- Neodymium, aluminum, garnet (crystal laser)
- Organic dyes (liquid laser)
- Chemical lasers
What depth can a gas lasing medium penetrate?
Superficial penetration (0.5-1.0 cm)
What are the effects of the different wavelengths?
- Ultraviolet: photochemical changes (ex. suntan)
- Infrared: Deep penetration (5-8 cm), thermal effects
- Visible (red) light: superficial penetration (.5-1.0 cm), both photochemical and thermal effects
What is dosage reported in?
Joules per square centimetre
What is dosage dependent on?
- Output of the laser in milli-watts
- Time of exposure in seconds
- Beam surface area of laser in cm2
What is the formula for the treatment time for a given area?
Ta = (E/Pav) X A
- Ta: treatment time for a given area
- E: millijoules of energy per cm2
- Pav: avergae laser power in milliwatts
- A: beam area in cm2
What are the different types of application techniques?
- Sequential: each square cm is lased
- Non-sequential: alternate grids are lased with overlap
- Scanning: no contact between probe and skin
What are the different frequencies and what are they used for?
- 2.5 Hz: for acute injuries
- 20 Hz: for wound healing
- 150 Hz: for pain relief
- 5 Khz: for chronic injuries and non-healing or infected wounds
What are some different treatment areas?
- Trigger points
- Acupuncture points
- Painful areas
- Open wounds, cuts, ulcers
What does LASER depth of penetration depend on?
The type of laser energy delivered
What does direct effect of depth penetration mean?
The response that occurs from absorption
What does indirect effect of depth penetration mean?
A lessened response that occurs deeper in the tissues; upper layers effected, affect the deeper layers
What is the depth penetration of HeNe?
Occurs within first 2-5 mm with an indirect effect of up to 8-10 mm
What is the depth penetration of GaAs?
1-2 cm with an indirect effect up to 5 cm
What are the indications of LASER?
- Wound healing: increased collagen synthesis
- Edema inflammation reduction: inhibiting inflammatory mediators
- Pain reduction: decreased sensory conduction, inflammation and increased healing
- Scar tissue: increased epithelialization and decreased exudate material
- Immunologic response: increased phagocytosis
- Bone response: increased consolidation
- Peripheral nerve regeneration
What are some precautions/contraindications for LASER?
- Safety goggles must be worn by both therapist and patient
- Do not use in pregnancy
- Do not treat eyes, over the heart
- Cancer, tumors
