laser Flashcards
what does laser stand for?
Light Amplification by Stimulated Emission of Radiation
what measurement are visible light wavelengths and what are the colors seen?
400-700nm
violet-red
infrared
ultraviolet
higher frequency= higher energy; which rays cause ionization?
x-rays, gamma rays and ultraviolet
light is transmitted as waves and is packaged as _____?
photons
what is spontaneous emission?
giving up energy
laser production needs what type of environment?
environment with unlimited excited ions
what is the term for the number of excited ions outweighing the number at grounded state?
population inversion
what causes population inversion and is the application of an external source of power to lasing medium?
pumping
what are the 5 things needed for the production of laser?
- pumping of active medium
- population inversion
- spontaneous emission
- stimulated emission
- amplification
what is the term for same wavelength and all in phase?
coherence
what is the term for a single color with the same wavelength?
monochromatic
when photons move in a parallel fashion and don’t diverge its called?
collimation
longer wavelength with lower frequency =
deeper penetration
what are the 4 types of lasers?
gas
solid
semiconductor
liquid
what is a semiconductor or diode type laser?
2 layers of material in a silicon matrix with the layer interface reflective
what is the therapeutic window for laser?
632.8-905 nm
what are the wavelengths for visible red?
600-700nm
what are the wavelengths for near infrared?
700-905nm
as the concentration of melanin or hemoglobin increase, the depth of penetration of light ______?
decreases
the wavelength of light will determine the overall _____ of penetration the photons will attain
depth
which type of laser was a gas laser originally and now a semiconductor with a wavelength of 632nm?
HeNe- more superficial
which laser has a wavelength of 630-700nm?
Indium-Galium-Aluminum-Phosphide
which laser is a longer wavelength of 904nm?
gallium-arsenide
with laser treatment you should cover each square centimeter of the treatment area what is this called?
gridding technique
an alternate method is the scanning technique, how far do you hold the laser from the patient?
5-10 mm from skin
what are the 4 laws discussed?
Arndt-Schultz
Grotthuss-Draper
Inverse square
Lambert’s cosine
photobiostimulation uses lower or higher doses of laser?
lower
photobioinhibition uses lower or higher doses of laser?
higher
with photobiomodulation photochemical effects are not from heating tissue but from absorption of?
photons of light by cells
what are molecules that accept energy from photons?
chromophores
what are respiratory chain enzymes in the mitochondria that are sensitive to light photons?
cytochromes
what are the 3 cellular mechanisms of laser?
- changes in Na-K channel
- Increase in intracellular Ca
- The Ca++ flux affects levels of cyclic nucleotides which modulate DNA and RNA synthesis which in turn modulates cell proliferation (biostimulation )
what are the biological effects of LLLT?
enhancement of ATP synthesis Stabilization of cellular membrane temperature modulation enhanced lymphocyte response reduced IL-1 prostaglandin conversion into prostacyclin increased leukocyte activity vasodilation via increased histamine, NO, serotonin
when photons are absorbed by tissues what is stimulated?
metabolic processes and cell proliferation through synthesis of nucleic acids and enhanced cell division
when photons are absorbed by tissues it also alters molecular-level activity. What does this affect?
ETC
increased ATP synthesis
decreased of intracellular pH
what is the process where a chain of chemical reactions is stimulated by exposure to light?
photostimulation or photobiomodulation
with photostimulation what happens to the cell?
it is provided with more energy and in optimum condition to play its part in the healing process
stimulation of the respiratory ETC results in what 2 major events?
- light changes the Redox status of mitochondria which leads to enhanced ATP synthesis
- activation of Na/K pump alters the cell membrane permeability to the flow of calcium
what effects are due to interaction of photons with cytochromes?
primary effects
what effects include cell proliferation, protein synthesis, degranulation, growth factor secretion, myofibroblast contraction and neurotransmitter modification depending on cell type and sensitivity?
secondary effects
what effect is least predictable because they depend on both variable environmental factors and intercellular interactions?
tertiary effects
primary, secondary and tertiary effects summate to produce _______?
phototherapeutic activity
what are the indications for laser therapy?
wound healing TMD myofascial pain osteoarthritis RA tendinopathy trigger points epicondylitis neck and LBP
what type of laser does the AHC use?
vectra genisys laser
what type of laser does the CHC use?
microlight ML-830
what are the different classes of laser?
Class I- invisible (laser printers, CD players) Class 1M Class II- low power Class III- moderate risk Class IV-high powered
which class of laser has a wavelength of 302.5-4000 nm and is safe except when used with optical aids?
Class 1M
which class is a visible laser that is hazardous if directed continually into the eye?
Class II
which class has a moderate risk to the retina but not the skin or tissues, must wear protective eyewear?
Class III
which class can cause damage to the eyes, skin burns and is a fire hazard?
Class IV- high powered; research labs, surgery, photothermal
light reflex response is absent with wavelengths over?
700nm
protective eyewear is required with what classes of laser devices?
Class IIIb and Class IV
what are the contraindications?
cancer pregnancy- abdomen and pelvis direct exposure to eyes areas over active hemorrhage over thyroid gland directly over open wounds epileptic patients
what are the precautions with laser?
infection testicles sympathetic ganglia, vagus nerve, cardiac region in those with heart disease open growth plates bruises photosensitive patients
what is dose measured in and dependent on (4)
Joules2
- output of the laser in mWatts
- number of diodes
- time of exposure in seconds
- beam surface area of the laser in cm2
which laser uses pulses or bursts of energy with higher peak power and less thermal effects?
super pulsed laser
the pulses of a super pulsed laser are the frequency of the laser emission NOT the ______
wavelength
what are 2 benefits of a super pulsed laser?
more directed energy delivery to target tissue
greater safety and enhanced clinical outcomes
the basic effect of a super pulsed laser irradiation is a ____ thermal influence with a ____ energy density
low; high
lower range of frequencies (0.25-500 Hz) are termed ____
bio-stimulatory
lower frequencies are used for:
repair and regeneration of tissue
immune response
anti-inflammatory effects
with super pulsed lasers frequency is defined as
the number of impulses per second
biological reactions are not only dictated by dose, but the rate at which the energy is delivered. this is called?
arndt schultz principle
what frequency and treatment time is used with an acute injury?
5-1000 Hz
3 minutes
smaller more frequent and localized doses are used with?
acute injuries
acute conditions usually shows results within
1-2 treatments
chronic conditions usually need how many treatments to show results?
3-4