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130 Cards in this Set
- Front
- Back
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What is the evidence for ultrasound?
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Very well designed animal studies which include:
Good evidence for pain relief, enhancing tissue healing and positive effects on connective tissues Cannot be said for humans |
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What is ultrasound?
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Form of acoustic energy requiring a medium to treat human tissues
Sound waves bump into adjacent molecules |
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What is frequency?
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number of occillations of a molecule undergoes during one second
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Hertz
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measurement of sound waves
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1 Hz
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1 cycle/second
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How are waves produced?
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waves travel in sinusodial pattern and include a positive pressure phase and negative pressure phase
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What makes it work?
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Piezoelectric crystal
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How does piezoelectricity work?
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property of many naturally occuring or synthetic crystals in which crystals generate an electric voltage when mechanically compressed or expanded
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What causes the voltage?
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The compression of the crystal
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1 MHz targets tissues at what depth?
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greater than 2 centimeters
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3 MHz or 3.3 MHz?
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targets within 1-2 centimeters below skin
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Higher frequencies do what?
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More oscillations and more work to overcome molecular friction
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What types of mode can you have?
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Continuous or pulsed
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What is a duty cycle?
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– fraction of time during a single pulse period that the beam of sound is present. Usually given in a percentage. Ex. 50%, 20%
Duty Cycle = duration of pulse (time on) / pulse period (time on + time off) |
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Pulse ultrasound is?
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NON-thermal
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What is intensity?
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Strength of power or quantity of energy produced by the US transducer.
Power is measured in Watts (W) Power is not uniform across an US transducer |
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What is the effective radiating area?
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Actual cross-sectional area of the ultrasound beam exiting metal end plate
Determined by size and vibrational properties of crystal Always smaller than area of metal end plater Expressed in square centimeters (cm²) |
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Transducer heads typically come in what sizes?
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5 or 10 centimeter
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What is spatial peak intensity?
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Acoustic power of ultrasound beam at highest point
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What is the Spatial average intensity?
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Average acoustic power across ERA
W/cm². Used clinically as intensity. |
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What is the beam-non-uniformity ratio?
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Ratio between spatial peak intensity and spatial average intensity
Determined by quality of the crystal and construction of transducer Required to be labeled on all machines and is usually listed on coaxial cable of the applicator |
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Generally the better the crystal?
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The more expensive!
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What are the 4 C's
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cut, clarity, color and carrot
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What is the spatial average temporal peak intensity?
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Spatial average intensity of the beam between interruptions during pulsed US
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What is the spatial average temporal average intensity?
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Accounts for impact of duty cycle
ISATA = ISATP * duty cycle |
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What formula can you use if you wish to figure out what parameters to use?
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US at 0.5 W/cm² X 100% duty cycle (cont.) = 0.5 W/cm²
US at 1.0 W/cm² X 50% duty cycle (pulsed ) = 0.5 W/cm² |
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How do the sound beams interact with the biological tissues?
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Gases and liquids
Longitudinal waves Parallel to direction of energy flow Solids Longitudinal and transverse waves Perpendicular to direction of energy flow |
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Waves can be? and depends on what?
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Transmitted
Reflected Refracted Absorbed whether it is a gas or a solid |
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Acoustic impedence at low impedence?
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ability of the material to transmit sound relates to density and structure of material. Transmition high and absorption low
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Blood have a high or low impedence?
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Low. transmitts very easily
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Bone, high or low impedence?
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high
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Relection and refraction occur when?
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Occurs when energy is transmitted through materials of differing impedances
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What determines the amount of reflection and refraction you get?
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Difference between materials at the boundary will determine how much of each
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If trying to decrease refraction do what?
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Soundhead in perpendicular with what is in contact with
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What is a standing wave?
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Occurs when reflected wave interacts with waves traveling away from the energy source
If both of these waves are in phase with each other energies are added More intense energy in the tissue Increased heat, burning |
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standing wave causes?
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Intense heat and burning when you are not moving the soundhead
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What is attenuation?
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Measure of the decrease in sound energy as the US travels, either by absorption, reflection, or refraction.
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should you cross the spine with the soundhead?
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NOPE!!!!!
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Thermal effects are due to what?
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friction between the molecules
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Lehman reported tissue elevation temperatures of?
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1°C to increase metabolic rate
2°-3°C to reduce spasm and pain and to also increase blood flow 4°C to increase collagen extensibility and inhibit sympathetic activity |
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What is the minimum time you can do ultrasound and bill for it?
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8 minutes
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8 minute rule?
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You must do something for 8 minutes in order to get 1 unit. But to get 2 units you must add 15 minutes and every 15 minutes is another 15 minutes
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What does microstreaming do?
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Can affect cell permeability and cellular activity
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What does cavitation do?
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Might contribute to diffusional changes across cell membranes and alterations in cellular function
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Popping your knuckle is an example of what?
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A cavitation
There are small little gas bubbles around the joint which when ultrasound hits it it causes it to pop! Pops small little gas bubbles |
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What is an unstable cavitation?
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Not likely during US at therapeutic intensities
Occurs at high intensities Violent collapse or implosion of gas bubbles Tissue destruction may occur |
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To heat deep muscle tissue
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Lower frequency = 1 MHz
Higher intensity = W/cm² Longer duration = minutes of treatment |
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To heat superficial muscle tissue
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Higher frequency = 3 MHz
Higher intensity = W/cm² Shorter duration = minutes of treatment |
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Tendons and ligaments heat up faster due to what?
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High collagen content
Avascularity |
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What did Chan and colleagues discover?
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Found that heating effects at patellar tendon reached required minimum of 4°C
Maintained for 15-20 minutes Stretch immediately following or even during US |
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Hemodynamic Effects?
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US energy is absorbed by tissue and temperature elevates
Local blood flow therefore also increases to dissipate heat and restore homeostasis Research? 50-50 at best that this occurs Based on the evidence: Small treatment, 1 MHz, and minimum of 5 minute treatment time |
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Effects on Nerves?
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Motor nerve conduction velocities
Research shows they can decrease, increase, or remain the same depending on parameters of treatment Sensory nerve conduction velocities Appear to increase with thermal doses of US Increased pain threshold? Possibly Unclear if actually due to US or associated vascular and thermal changes in treated area |
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Ultrasound on wound healing?
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Wound healing
Animal studies show increased wound healing with increased new vessel formation and collagen deposition |
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Inflammation and tissue repair in ultrasound?
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In vitro research shows US to have an effect on cells active during acute inflammation and tissue repair.
Collagen synthesis Cellular proliferation Increase in fibroblast proliferation |
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Muscle healing and contusions?
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More animal studies
Wound Healing Human trials are inconclusive Muscle Healing Possible increased fibroblasts during healing phase Possible increased force production Overall it’s unclear if US would be an effective treatment |
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What have they discovered in peripheral nerve healing in ultrasound?
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Low intensity may help
Animal studies Increased amount of regenerating nerve fibers, myelinization, diameter of nerve and Schwann cell activity of sciatic nerve of rat with pulsed ultrasound |
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Tendon and ligament healing for ultrasound?
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More animal studies
US to Achilles tendons in rats had more densely aggregated collagen fibrils with parallel alignment Increased tensile load However no changes with chicken tendons Dogs Resumed normal gait sooner Evidence of more advanced healing relative to controls |
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Tendon and Ligament healing?
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Human studies
Lateral ankle sprains No support for use of US Shoulders No significant effect Calcific tendonitis of the shoulder |
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What is the only supported use of ultrasound in humans?
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Calcific tendonitis of the shoulder
Helps break up the calcium deposits |
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Fracture healing and articular cartilage repair
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US used in form of a bone stimulator
Effective in healing non-union fractures Most studies done on animals using a SAFHS machine (sonic accelerated fracture healing system). |
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What are the basic components of the ultrasound?
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Basic Components
Console Coaxial cable Transducer Typical sizes are 5 cm² & 10 cm² |
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Transducer
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Crystal-2 to 3 cm in width
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Uses for deep heat
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As deep heat:
Joint contracture and scar tissue Pain and muscle spasm Subacute or chronic soft tissue inflammation Requiring increased temperature or blood flow |
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For facilitating healing
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Facilitate healing
Acute injury/inflammation of soft tissue or peripheral nerve Open wounds Fractures |
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Ultrasounds have been used to diagnose what?
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broken bones. It lights you up!
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What are some of the contraindicatons?
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In the region of a cardiac pacemaker
During pregnancy Over abdominal, pelvic, or lumbar region Over eyes and testes In a region of active bleeding or infection In a region of a tumor or malignancy In a region of a DVT or thrombophlebitis Over the heart, stellate or cervical ganglia Over epiphyseal plates or growing bones Over the spinal column |
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What are some general precautions?
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Sensation of area being treated
Communication or cognitive deficits Poor circulation or vascularity Treatment over plastic or metal implants Bone cement is highly absorptive Metal is highly reflective – increase risk of standing waves and increased heat or unstable cavitation. |
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Moving the sound head does what?
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Moving the sound head
Decreases risk of standing waves Increases patient comfort Allows for more even spatial distribution of energy. Treatment area should be 2 x ERA of the transducer. |
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Why would you use a stationary sound head?
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Stationary sound head
Used in bone stimulators Parameters are fixed and device has multiple crystals |
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What is the most typical way to apply it?
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Direct Contact Coupling
US waves do not travel effectively through air Coupling medium is required to transmit energy between transducer and patient’s body Use direct contact when area of treatment is flat and as large as the transducer face Use of water soluble gel or lotion is placed on the patient’s skin and direct contact is made with the transducer and the gel. This eliminates excess air, reducing reflection back on the sound head |
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What is phonophoresis?
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Use of US to enhance delivery of medication through the skin.
Theory is that US enhances the transdermal diffusion of medications through such mechanisms: Dilating points of entry (hair follicles, sweat glands) Increasing local circulation Increasing kinetic energy of local cells and the medication itself Increasing cell membrane permeability |
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Measurements and expected outcomes?
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Pain assessment
Tenderness to palpation ROM measurements Flexibility assessment Wound measurements Manual muscle testing |
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Documentation?
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Parameters of treatment
Frequency Intensity Duration Mode Treatment area Patient position Application technique Transducer size Sequence within treatment session |
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What is ultrasound?
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It is a therapeutic modality commonly used for improving connective tissue extensibility (ability to stretch), managing scar tissue, promoting pain relief, and enhancing tissue healing and remodeling in the care of tendinopathies
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What has well designed animal studies taught us?
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that ultra sound has positive effects on connective tissue characteristics, pain and tissue inflammation and healing
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What is ultrasound a form of?
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Acoustic or sound energy
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What are sound waves?
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Sound waves are mechanical pressure waves
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What does acoustic energy require?
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It requires a medium such as a coupling gel when treating human tissues
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what kind of gel is used?
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water soluble
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how do sound waves travel?
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by mechanically vibrating molecules. A vibrating molecule then bumps into other molecules and transfers heat and sets the molecule into motion as well this chain reaction occurs until energy is dissipated into the tissue
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Why does sound energy travel faster through denser connective tissue such as tendons and bones?
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Because the molecules are so close together than they transfer energy faster cause they collide more quickly into adjacent molecules
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What defines the frequency of a sound wave?
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The number of oscillations a molecule undergoes during 1 second and is measured in hertz
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what does 1 Hz equal?
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1 Hz equals 1 cycle per second
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Humans can hear what?
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Humans can hear ranges from
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What happens at low frequency sound ranges?
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sound waves diverge like an open light
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What happens at high frequency sound waves
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the wave is more collimated, diverging less
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What is a sinusoidal pattern?
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Up and down pattern
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What is a positive pressure phase?
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It is where molecules adjacent to the energy source are compressed together resulting in a high wave
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Areas of compression are known as?
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condensations
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areas of decreased molecular density are?
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rarefactions
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In Ultrasound what are the pressure waves generated by?
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They are generated by oscillations of a piezoelectric crystal induced by passing voltage from a high frequency alternating current across its face
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Where is piezoelectricity naturally occuring?
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natural and synthetic crystals
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What is piezoelectricity?
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The phenomenon that a crystal produces an electric charge when mechanically compressed
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When a crystal is expanded what happens?
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The crystal will then produce an opposite polar charge
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What can happen if you apply a charge to a crystal?
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You can make it either expand or compress depending on the charge
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What is the reverse piezoelectric effect?
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It is changes in the polarity of the applied voltage that results in expansion of a compressed crystal and vice versa
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What produces the ultrasound pressure wave? What makes the molecules move and transfer heat?
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Repeated cycles of compression and expansion
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What is the frequency of the wave dependent upon?
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It is dependent upon the frequency of the imposed alternating electrical current across the crystal
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How is the velocity computed?
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velocity is equal to frequency (duty cycle) times the wavelength
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What are the two most common frequency settings of ultrasound?
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1 MHz or 3 MHz
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Which MHz is selected for target tissues 1 to 2 centimeters from the body surface?
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3 MHz
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Which MHz is selected for tissue depths below 2 centimeters?
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1 MHz
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What two mode options do you have?
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Continuous or pulsed
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What is the continuous wave mode?
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When ultrasound is administered in a continuous wave
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What is a pulsed mode?
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Ultrasound is deleivered with periodic episodes of rest
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What is a duty cycle?
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Fraction of time during a single pulse period that the ultrasound beam is present in miliseconds
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What is continuous wave ultrasound used for?
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For its thermal properties
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What is 20% duty cycle used for?
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nonthermal healing effects by the movement of ions across a cells membrane
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What is the strength of the ultrasound wave determined by?
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It is determined by the quantity of energy acoustic power produced by the transducer
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What is the ERA?
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the effective radiating area
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What determines ERA?
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Size and vibrational properties of the crystal that is being used
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What is the term spatial peak intensity mean?
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refers to the acoustic power of the ultrasound at its highest point
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Where does the spatial peak intensity usually located at?
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somewhere along the central third of the of the ERA
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What does Isp stand for?
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Spatial peak intensity
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What does Isa stand for?
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spatial average intensity
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In solids, molecular vibrations occur in longitudinal waves parallel with the flow of energy and how else?
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Transverse as well perpendicular to the flow of energy cause of the strong 3 dimensional intermolecular bonds present in solid media
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What do human tissue besides corticol bone at like with acoustic vibrations?
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They act like liquids
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What does acoustic impedence mean?
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refers to a materials ability to transmit sound and is related to the molecular density and structure of material
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When do reflection and refraction occur?
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when energy is transmitted between materials with different impedences
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For example when ultrasound passes through skin to muscle some of the energy is reflected back into the skin
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When a wave strikes a boundary at an angle the angle of reflection is equal to and opposite the strike angle
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What is standing wave?
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When a reflected wave travels back through its original path and it interacts with waves going in the opposite direction they have their energies added together and then you have a very intense wave
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Refraction is what?
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Waves being bent as they pass from one medium to another such as in bowfishing for carps
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What is attenuation?
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It is a measure of the decrease in sound energy as the sound wave travels
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If the angle of the unltasound beam is greater than 15 degrees to the perpendicular what occurs?
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The beam is refracted and and runs parallel to the skin
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What does a 1 degree celcius temperature raise result in?
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Increases metabolic rate
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A tissue elevation of 2-3 degrees celcius results in what?
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Reduces muscle spasms and pain and increases blood flow
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What occurs at a 4 degree celsius change?
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boost collegen extensibility and inhibit sympathetic activity
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What is microstreaming?
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small magnitude movements of intracellular and extracelluar movements that alter cell membrane permeability and cellular activity
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What is cavitation?
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the pulsation of gas bubbles in human tissue expansion and compression and may contribute to diffusional
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What is an unstable cavitation?
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a violent collapse of a gas bubble that results in tissue damage
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