Lecture 4: Diathermy and Laser EMR Flashcards
EMR is composed of what
electric and magnetic fields that vary overtime and are oriented perpendicular to one another
how are humans exposed to EMR daily
natural UV radiation
manufactured in lightbulbs, computers, appliances, etc
what frequency is good for EMR
high frequency bad, low frequency good
how can physical agents deliver energy in the form of EMR (I.e what types of PAs)
light = electromagnetic energy close to visible range
infared radiation = superficial healing
microwave and shortwave = diathermy
EMR is categorized by what
frequency and wavelength (inversely proportional)
what does it mean that lower frequency EMR is nonionizing
i.e. short wave, microwaves, IR, visible light, UV
nonionizing = cant break molecular bonds and thus is medically safe
what does it mean that higher frequency EMR is ionizing
i.e. xrays and gamma rays
can break molecular bonds to form ions and inhibit cell division so not used clinically except for very small doses for imaging or large doses to kill cancerous cells
when is intensity of EMR greatest
high energy output
radiation is a source close to pt
beam is perpendicular to skins surface
physiological effects on subject for EMR depends on
frequency
wavelength
intensity of radiation
what is diathermy
conversion mode of heat transfer
EM energy causes RT of polar molecules that cause friction and thus produce heat
continuous vs pulsed diathermy parameters
continuous = 10-25 watts; can be SWD or MWD
pulsed = low intensity; nonthermal; SWT
types of applicators for diathermy
inductive coil = heat in deeper tissues with high electric conductivity
capacitive plates = more heat in skin/superficial tissues
magnetron = not common
thermal effects of diathermy
SWD/ continuous
vasodilatuion
increased rate of n conductuion
reduced pain
increased soft tissue extensibility
accelerated enzyme activity
non thermal diathermy effects
SWT
pulsed = nonthermal b/c transient heat of tissues will diffuse between pulses
modulates pain/edema/inflammation
increased microvascular perfusion
increaed blood flow/circulation
advantages of diathermy
deep heat
large areas
no direct contact
clinically indicated to reduce pain and improve muscle performance with knee OA
common in SNF
disadvantage of diathermy
not widely used
EM field cant be contained and can interfere with other equipment
large/expensive
nonthermal SWT clinical uses for diathermy
reduces edema/pain
accelerate tissue healing
application of diathermy
position drum- no contact
wrap in towl
can cover drum in plastic
remove metal
no use with pt with implanted stimulator
times for diathermy thermal vs nonthermal
thermal = ~20 min
nonthermal = 30-60 min 1-2x/day
what to be aware of with diathermy
burns
varies with tissue type
wrap pt skin in towel
don’t be around with pregnancy or pacemaker
levels of diathermy and their wattage
1 = 0; lowest
2= 12; low
3= 24; medium
4= 48; heavy
manually = initially start with 10-25
what is light
EM energy close to visible range of electromagnetic spectrum
most light = polychromatic (various wavelengths of light)
what is LASER light
light amplification by stimulated emission of radiation
monochromatic (single wavelength) , coherent (waves in phase/stick together), and directional (little divergence i.e. laser pointer)
what is low level laser therapy (LLLT)
low intensity cold laser
low lightlevel used in visible red/IR range
used to promote tissue healing
control pain/inflammation
what are high intensity hot lasers
used for surgery
can destroy tissue
narrow beam generates heat with selective tissues
cauterizes as it cuts
not used for rehab
what do we mean not all lasers are LASERS
light devices are named based on what type of photodiodes theyre comprised of
some laser devices are comprised of multiple photodiodes including laser and LED diodes
a cluster probe is an applicator with more than 1 diode or type of diode of various wavelengths/power
what are photodiodes
small, sturdy, inexpensive conductors of energy
semiconductors with positive and negative charges that output energy
types include laser diodes, LEDs, SLDs
what is LED
infared laser
technically not a laser
light appears to be 1 color but it is neither coherent or monochromatic
nondiretcional (diffuse spread of light; covers larger areas)
low energy concentration (longer application times are tolerable)
what is SLD
supra luminous diode
monochromatic, noncoherent, nondirectional, deeper penetration
nondirectional (between LED and LASER)
high intensity = shorter application times
what is wavelength
affects depth of tissue penetraction
longer = deeper
IR is deeper than visible light
some LEDs are deeper than LASERs
what is power
unit of light intensity
determines clinical effects
hot = high intensity = high power
cold = low = low
what is power density
irradiance
light intensity per unit of area
what is energy
determines dose
power over period of time
Energy = power x time
what is energy density
fluence of treatment
energy/unit of area
preferred measure of dose
light treatment dose based on clinical indication
duration depends on dose
how do lasers/light affect the body
photons are absorbed by chromophores causing a cascade of cellular changes
chromophores = part of molecule that gives tissue color by absorbing/reflecting different wave lengths
absorbed photons can stimulate chromophores to undergo chem reactions and promote cascade of biochem events that influence tissue fxn
6 specific physiological effects of laser/light therapy
1 = stimulate mitochondria to produce ATP (up to 70%)
2= stimulate production of mRNA ro promote fibroblasts and increase collagen production
3=induce vasodilation/circulation
4=inhibit bacterial/fungi growth
5=modulate inflammaiton by decreasing mediators
6=improve nerve conduction and regeneration after injury
how can lasers be used with wound healing/fx healing
soft tissue and bone healing
how can lasers be used with neuro condition
carpal tunnel
diabetic peripheral neuropathy
alters n conduction velocity
how can lasers be used with MSK disorders
soft tissue/arthritic conditions
reduce inflammatory mediators
how can laser be used with lymphedema
treating post masectomy women to reduce limb volume associated with lymphedema post breast cancer
how can laser be used with pain management
arthritis, tendinopathy, TMJ, DOMS, LBP, neck pain, trigger points, chronic pain
alalgesic effects most effective when directly over involved dermatome
clinical indications for laser treatment dose
low dose - more acute/superficial conditions
high dose = chronic/deeper conditions
higher dose = longer treatment
average dose = 4-12 J/cm^2
**dose automatically adjusts treatment time
protection for performing laser treatment
wear goggles - PT and pt
goggles should not wavelength range they protect from
don’t point towards eyes, even if you can’s visibly see laser
does laser risk burns
rare with low level class 3B lasers are harmless to skin generally; no thermal effect
diodes can cause burns if left for a long period of time; thus LEDs that require longer treatments should not be used for pts with poor sensation
contraindications for lasers
direct to eyes
within 4-6 months of radiotherapy
hemorrhagic lesions
locally to endocrine glands
malignancy
precautions for laser
pregnancy - low back/abdomen
epiphyseal plates
impaired sensation/mentation
photophobia
high sensitivity to light
pretreatment with photosensitizers (meds can increase photosensitivity)
what to document when useing a laser, LED, SLD, or light therapy
type of diode (laser, LED, SLD)
wavelength (nm)
power (mW)
area of bidy
treatment dose/energy density (J/cm^2)
duration not included b/c automatic
