EMR Physical Agents: Diathermy and Laser Flashcards
What is electromagnetic radiation (EMR)?
composed of electrical and magnetic fields that vary over time and are oriented perpendicular to one another
What is natural EMR?
- uv radiation from sun, magnetic field of earth
What is manufactured EMR?
- light bulbs, computers, appliances
What is light in terms of EMR?
- electromagnetic energy in or close to visible range of electromagnetic spectrum
What is infrared radiation used for?
superficial heating
What are microwave and shortwave used for (physical agent)?
Diathermy
What is EMR categorized by?
its frequency and wavelength
Frequency and wavelength of EMR are ________ ___________
inversely proportional
What kind of EMR is nonionizing?
Lower frequency (longer wavelength)
What are examples of lower frequency EMR?
- shortwaves
- microwaves
- IR
- visible light
- UV
Can nonionizing radiation break molecular bonds?
NO - medically safe :)
What kind of EMR is ionizing?
Higher frequency (shorter wavelength)
What are examples of ionizing EMR?
- x rays
- gamma rays
What does ionizing mean?
can break molecular bonds to form ions and inhibit cell division
Is ionizing EMR used clinically?
VERY small doses for imaging (x-ray)
- LARGE doses to intentionally destroy tissue (cancer treatments)
_____ in large doses can become ionizing
UV
When is intensity of EMR greatest?
when…
- energy output is high
- radiation source is close to the patent
- beam is perpendicular to the skins surface
What do the physiological effects of EMR on the subject depend on?
- frequency/wavelength (types of EMR, ionizing or nonionizing)
- intensity of the radiation
What is energy(J) equal to?
power (W) x time (s)
What mode of transfer is diathermy (thermal)?
- conversion mode of heat transfer
What is thermal diathermy?
- an electromagnetic form of energy which causes the rotation of polar molecules, “converts” to heat when friction between the molecules increases tissue temp
What is the range of shortwave diathermy? (SWD)
1.8 - 30 MHz
What is the intensity of continuous diathermy to generate heat?
10-25 watts intensity generates heat
What is pulsed diathermy?
- low intensity
- nonthermal and produces other physiological changes
- non thermal shortwave therapy (SWT)
What are the types of applicators used with diathermy?
- inductive coil -> produces most heat in deeper tissues with high electrical conductivity
- capacitive plates -> more heat in skin/superficial tissues
- magnetron (not common)
What are thermal effects of continuous SWD?
- vasodilation
- increased rate of nerve conduction
- reduction of pain
- increased soft tissue extensibility
- accelerated enzyme activity
What are nonthermal effects with SWT?
- pulsed will not have thermal activity bc the transient heat of tissues will diffuse between pulses
- modulated pain, edema, and inflammation through altered cell membrane function and activity
- increased microvascular perfusion
- increased blood flow/circulation
What is continuous SWD used for clinically?
produces thermal effects in deep tissues
- increased circulation in skin, subcutaneous tissues and muscles
What are advantages of continuous diathermy (SWD)?
- can heat larger areas that US
- can heat with more depth than heat packs
- can be used when direct contact contraindicated
What are disadvantages of diathermy?
- not widely used
- EMR field cannot be readily contained and can interfere with other equipment
- equipment is large, expensive and cumbersome
What are the clinical used of Nonthermal shortwave therapy (SWT)?
- accelerates edema resolution
- reduce pain after injury
- accelerate soft tissue healing
Where is SWT seen most often? Why?
in SNF
- long duration of treatments
- no med equipment to interfere with
What should the positioning of the drum applicator allow?
An air gap for heat to dissipate
- pt must remain still to maintain gap
What should we avoid with positioning of drum?
direct contact with skin, esp when infection present
Why do we wrap the area to be treated with a towel with diathermy?
- to absorb patient perspiration
- avoid potential burns
What can we do to the applicator to minimize risk of cross contamination?
Cover with plastic
What needs to be removed before a diathermy treatment?
Jewelry and other metal objects
- be mindful of bras with underwire
What type of patient should we NEVER use diathermy on?
patients with implanted stimulators
- such as deep brain stimulators or pacemakers
What are the treatment parameters for diathermy?
- thermal ~20 mins
- nonthermal: 30-60 minutes once or twice a day
What can happen with diathermy at normal intensities that we need to be aware of?
BURNS
- soft tissue
- caries significantly with the type of tissue
- fat layers are at greatest risk of burning (not well vascularized = not cooled as effectively by vasodilation)
Why do we wrap a patient in towels to avoid burns?
- water is preferentially heated by all forms of diathermy, to avoid scalding by hot perspiration, the patients skin needs to be kept dry
Why should a patient not stand near the diathermy unit?
if they are pregnant or have a pacemaker
What are the levels of dosage for diathermy?
- Level I = 0 watts
- level II = 12 watts
- level III = 24 watts
- level IV = 48 watts
What is most light?
polychromatic (consists of various wavelengths of light)
What is LASER light?
- Light Amplification by Stimulater Emission of Radiation
What are the different types of laser light?
- monochromatic (single wavelength)
- coherent (waves are in phase, stick together)
- directional (little divergency, laser pointer)
What is low-level laser therapy? (LLLT)
- low intensity “cold” lasers
- low level light devices in visible red and IR range
What is LLLT used for?
- promote tissue healing
- control pain and inflammation
What are high-intensity “hot” lasers?
- used for surgery, destroy tissue
- narrow beam generates heat within selective tissues and destroys tissue, cauterizes as it cuts
- NOT USED FOR REHAB
Are all lasers “LASERS”?
NO
What are light devices names based on?
What type of photodiode they are comprised of
Are some “Laser” devices comprised of multiple photodiodes?
Yes, including laser and LED diodes
What are photodiodes?
- small, sturdy, inexpensive conductors of energy
- semiconductors with positive and negative charges that output energy
What are some photodiode types?
- laser diodes
- LEDs
- SLDs
Why is LASER monochromatic?
- remains at ~ 632.8 nm wavelength
- coherent
- directional
- superficial penetration ~ 5 mm
What color does LASER appear in the visible light spectrum?
RED
What does the color of the light depend on?
wavelength (usually red)
What does LED stand for?
Light - Emitting Diode
What kind of laser is LED?
infrared laser
- not technically a laser
- light appears one color but not coherent or monochromatic
Why is LED nondirectional?
- more diffuse spread of light
- coverage of larger treatment areas
What does it mean that LED is low concentration of energy?
Longer application times tolerable
What kind of LED laser is most commonly used for patient treatment? Why?
Red LED lasers, best depth of penetration into human tissue
What is the depth of penetration of red LED laser into human tissue?
~ 600-700 nm
What is an SLD?
- Supra Luminous Diode
What are the characteristics of SLD?
- almost monochromatic
- non-coherent
- nondirectional (spreads less than LED but more than LASER)
- deeper penetration 2-4 cm
- high - intensity (shorter application times)
What are the properties of light therapy?-
- wavelength
- power
- power density
- energy
- energy density
What does the wavelength affect with light therapy?
- depth of tissue penetration
What type of wavelength penetrates deeper?
longer deeper than shorter
What penetrates more deeply than visible redlight?
IR
Can LEDs penetrate deeper than LASERs?
Yes, some
What is power of light therapy?
Unit of light intensity (mW)
What does power of light therapy determine?
Clinical effects
- hot lasers = high power
- COLD lasers = low power
What class of cold lasers is used for therapy?
3B
What is power density also known as?
Irradience
What is power density of light therapy measured in?
mW/cm2
What does the energy of light therapy determine?
Dose
What is energy of light therapy?
power over a period of time
Energy (J) = Power (W) x Time (s)
What is the energy density also known as in light therapy?
“Fluence” of treatment
What is the energy density measured in?
Energy / Unit of area (J/cm2)
What is the energy density based on ?
Clinical indication
What is duration of energy density dependent on?
Dose
- clinician does not change time of treatment
What are chromophores?
- part of a molecule that gives tissue its color by absorbing some wave lengths and reflecting others
How are photons absored?
by chromophores causing a cascade of cellular changes
What can absorbed photons (light energy) stimulate chromophores to do?
- under go chemical reactions and promote a cascade of biochemical events that influence tissues function
What are the physiological effects of light therapy?
- stimulate mitochondria to produce more ATP**
- stimulate production of mRNA to promote fibroblasts increased collagen production
- induce vasodilation/circulation
- inhibit bacterial/fungi growth
- modulate inflammation by decreasing mediators
- improve nerve conduction and regeneration after injury
What primarily generates ATP?
Mitochondria
What is ATP used for?
energy source in all cellular reactions
What does laser light do to the mitochondria?
- improves mitochondrial function and increases ATP production by up to 70%
What is the evidence for clinical usage of light therapy?
EVIDENCE IS VERY LIMITED
- may be biomodulating and facilitate healing
What are clinical indications of light therapy?
- WOUND HEALING / fx healing
- neurological conditions
> CTS, diabetic peripheral neuropathy, alters nerve conduction velocity - MSK disorders
> soft tissue and arthritic conditions due to reduction in inflammatory mediators - Lymphedema
> treatment in axillary region of women post mastectomy to reduce limb volume - pain management
> arthritis tendinopathy, TMJ, DOMS, LBP, neck pain, trigger points, chronic pain
> analgesic effects most pronounced when laser/light applied to skin overlying the involved nerves or dermatomal area
What are low dosages of light therapy used for?
- more acute or superficial conditions
What are higher doses of light therapy used for?
chronic or deeper condiotns
What happens with a higher dose of light therapy?
increased duration of treatment
What is the AVERAGE treatment dose for light therapy?
4-12 J/cm2
Why do we wear goggles with light therapy?
SAFETY
- both clinician and patient should be wearing protective goggles
- should be marked indicating the wavelength range they attenuate (block)
- dont point in your or the pt’s eyes & never look directly in it
What kind of lasers can emit light that is not visible but can still damage the retina?
IR lasers
What should we know about units and goggles?
- only use goggles provided with the laser unit, other goggles/glasses nonspecific to that unit will not prevent possible eye damage
Are burns rare with light therapy?
YES (3B)
What will happen if the diodes are on for a prolonged period of time?
they will become warm
What is a concern with LEDs?
long time to deliver therapeutic done of energy
What type of patient are LEDs not appropriate for?
those with poor sensation or mentation
What are some contraindications of light therapy?
- directly to eyes
- within 4-6 months of radiotherapy
- hemorrhagic lesions
- locally to endocrine glands
- malignancy
What are some precautions with light therapy?
- pregnancy (to LB or abdomen)
- epiphyseal plates
- impaired sensation or mentation
- photophobia
- high sensitivity to light
- pretreatment with photosensitizers (medications)
What do we document when using laser, LED, SLD, light therapy?
- type of diode
- wavelength
- power
- area of the body treated
- treatment dose/ energy density
