Week 9 Flashcards

1
Q

LASER acronym

A
Light
Amplification by
Stimulated
Emission of
Radiation
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2
Q

Quantum Physics

A

In 1917, Einstein proposed the possibility of stimulated emission, the physical process that makes the maser and the laser

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3
Q

Review components of the first ruby laser

A

Pg. 6

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4
Q

Low intensity laser therapy (LILT)

A
synonyms
-therapeutic laser
-low level laser therapy
-low power laser therapy
low level laser
low power laser 
low energy laser
soft laser
low reactive level laser
low intensity-level laser
photobiostimulation laser
photobiomodulation laser
mid laser
medical laser
biostimulating laser
bioregulating laser
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5
Q

Class of lasers

A
Class I : low power lasers
Class II: power out put up to 1mW (400-700nm wavelength)
Class IIIa: power out put up to 5mW
Class IIIb: power output up to 5-500mW
Class IV: Power output up to 500-700mW
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6
Q

Lasing medium

A

a substance of being ‘pumped’ with energy
gaseous mixture
-helium neon (He-Ne) red light 632nm
Gallium - arsenide (Ga-As) red light 632nm
*Gallium - aluminium-arsebude (GAAIAs) semiconductors visible red to near infra red 630-950nm

*cheaper, higher power, less dangerous to eyes

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7
Q

Resonating cavity

A

chamber to contain lasing medium
contains a pair of parallel reflecting surfaces / mirrors
Photons are reflected back and forth to produce an intense photon resonance
one reflecting surface (output coupler) is not a perfect ‘mirror’ and allows output of the light

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8
Q

Power source

A

a power source is required to ‘pump’ the lasing medium to produce stimulated emission
Usually mains supplied power but can be battery operated e.g. rechargeable NiMH x20AA

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9
Q

Characteristics of laser radiation

A

monochromaticity
collimation
coherence

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10
Q

Monochromaticity characteristics

A

single coloured
clustered around a single wavelength
wavelength is a critical factor for determining biological effect

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11
Q

Collimation characteristics

A

rays of light / photons are all parallel
almost no divergence over distance
optical power is ‘bundled ‘ on to a small area
but increases danger to the eye

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12
Q

Coherence characteristics

A

light emitted is in phase
troughs and peaks perfectly matched
-in time (temperal coherence)
-in space (spatial coherence(

And crawling on the planet’s face some insects called the human race lost in time, and lost in space and meaning

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13
Q

Laser tissue interaction LILT

A

Scattering of incident light
- change in direction of light as it passes through tissue with varying refractive indices relative to water content = loss of coherence

absorption of incident lightr

  • chromophores are biomolecules that absorb photons and include melanin and haemoglobin
  • therefore penetration is limited to several millimetres but is wavelength dependant
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14
Q

Laser tissue interaction LILT

A

of these two modes, absorption is the most important in terms of the photobiological basis of laser therapy

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15
Q

photobiological effects of laser

A

Multiple possible effects
complex interactions
irradiation parameters based
poorly understood

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16
Q

Arndt-Schultz law/rule

A

weak stimuli increases physiologic activity, moderate stimuli inhibits activity, and very strong stimuli abolish activity

17
Q

Biological and physiological

A

cellular research
animal studies
human studies

18
Q

cellular research

A

fibroblasts
macrophages
collagen production

generally positive results but come equivocal

19
Q

Animal studies

A
photobiostimulatory effects of wound healing 
-bone defects
burns
soft tissue injury
nerves

antinociceptive

  • hypoalgesic effect noted
  • naloxone reversible in some studies
20
Q

Human studies

A
experimentally induced pain 
-variable findings
nerve conduction
-clinical relevance
clinical trials 
-limited due to poor design
Wound healing 
-ulcerated lesions (variable findings)
21
Q

Human studies cont

A

`arthritic conditions
-mixed conclusions
RA relief of ain and stiffness short term

Msk conditions

  • most studies and applied area
  • confusion over parameters confounds research
  • tennis elbow equivocal
  • tendon disorders - mostly positive
22
Q

Principles of clinical application

A
indications
-wound management
soft tissue injuries 
arthritis 
pain relief
23
Q

Dosage and irradiation parameters

A
Power output 
-expressed in milliwatts (mW)
-more powerful machine (30-200mW) now common as deliver energy quicker 
Irradiance (power density)
-mW/cm2
-usually kept high 
Energy
-joules (j)
-power output in W x secs application 
e.g. 30mW device for 60 sec = 1.8J
24
Q

Dosage and irradiation parameters

A

pulse rate

  • Hz
  • Variable Hz to kHz
Treatment 
-keep treatment head in contact with tissue 
-reduces accidental intrabeam viewing 
-decreases inverse square law 
Useful for trigger/acu-points
25
Q

Open wound ulcers

A

two stage technique

  • contact around wound margins
  • non contact over wound bed
26
Q

Indications of laser therapy

A

increasing local blood circulation
relieving minor muscle and joint aches, pains and stiffness
relaxing muscles
relieving muscle spasms
relieving minor pain and stiffness associated with arthritis
promoting nerve regeneration, bone growth, and ligament repair
healing wounds

27
Q

Contra-indications of laser therapy

A

for direct aim into eyes of humans or animals
over areas injected with steroids in the past 2-3 weeks
over areas that are suspicious or contain potentially cancerous tissue
over areas of active haemorrhage
over a pregnant uterus
over the neck (thyroid or carotid sinus region) or chest (vagus nerve or cardiac region of the thorax)
directly over areas with open wounds unless covered with a clear. protective barrier
treatment over sympathetic ganglia
for symptomatic local pain relief unless etiology is established or unless a pain syndrome has been diagnosed
infections, diseases
over bony growth centres
thoracic area with pacemaker
eye
vascular diseases