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64 Cards in this Set
- Front
- Back
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Form of acoustic or sound energy which travels through vibration |
Ultrasound |
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Ultrasound is a (superficial/deep) modality |
Deep |
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frequency of ultrasound waves |
>20,000 Hz |
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frequency of therapeutic waves |
0.7-3.3 MHz |
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Therapeutic ultrasound is for |
Soft tissue inflammation and pain For increasing tissue extensibility, scar tissue remodelling, and healing acute soft tisssue injuries |
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2 main parts of ultrasound |
Generator and Applicator |
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Largest part of ultrassound; what we call the big box of the device |
Generator |
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Part of the generator that generate the high-frequency alternating current |
key component |
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Part of the generator that raises the voltage from the power source |
Transformer |
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Part of the generator that modifies frequency |
Oscillator circuit |
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This transfers electrical energy from console to the transducer |
Coaxial cable |
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Housing for the crystal and sound head that facilitates application of ultrasound |
Applicator |
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Two key elements of applicator |
Piezoelectric crystal Soundhead |
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Key element of applicator that converts electrical energy into sound or acoustic energy that is transmitted by the soundhead |
Piezoelectric crystal / transducer |
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Key element of applicator that covers the irradiating surface and is connected to the piezoelectric crystal |
Soundhead / transmitter / applicator's faceplate |
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When the crystal is subjected to mechanical deformation, it generates a potential difference |
Piezoelectric effect |
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Ultrasound causes it to respond tot eh alternating current by expanding and contracting at the same frequency at which the current changes polarity |
Reverse piezoelectric effect |
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Frequency for compression, expansion, and alternation |
1-3 MHz |
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Number of waves per second delivered to the patient |
Frequency |
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Frequency of (1/3) MHz penetrates superficial tisssues and absorbed at deeper tissues |
1 MHz |
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Frequency (1/3) MHz is absorbed at superficial tissues |
3 MHz |
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Uneven intensity produces a high level of energy in the center of the US beam relative to the surrounding areas |
hot spot or spatial peak intensity |
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Acoustic power of the ultrasound beam at its highest point |
Spatial Peak Intensity |
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Measure of the average acoustic power across the ERA |
Spatial Average Intensity |
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Formula for spatial peak intensity |
Power (watts)/ ERA (cm^2) |
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Gross measure of the power being emitted by the treatment head |
Intensity |
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Mode of US that is delivered at a constant energy level throughout the treatment; thermal |
Continuous US |
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Mode of US where there is a periodic cessation of the energy flow; non-thermall |
Pulsed US |
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Formula for Temporal Average Intensity (TAI) |
(Pulse duration/pulse period) x 100 |
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Time where energy is flowing |
Pulse duration |
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Combined time of energy flow and lack of flow; on-off time |
Pulse period |
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Ratio between the spatial peak intensity measured anywhere within the ERA and the spatial average intensity averaged over the entire ERA |
Beam non-uniformity ration (BNR) |
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Lower BNR means |
More uniformly shaped beam |
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higher BNR means |
More likely to cause discomfort due to hot spots |
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Area of the transducer from which the ultrasound energy radiates |
Effective Radiating Area (ERA) |
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T/F use Diathermy instead for large areas |
True |
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Physical Phenomena |
Reflection Refraction Attenuation Absorption |
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Refers to resistance to passage of ultrasound |
Acoustic impedence |
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High transmission, material absorbs little sound |
Low acoustic impedence |
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Less transmission, material absorbs more energy |
high acoustic impedence |
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Reflection of an incident beam away from a surface at an angle equal & opposite to the angle of incidence |
Reflection |
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Bending of waves as they pass from one medium to another in proporition to the difference in acoustic impedence |
Refraction |
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(Bone/blood) highest absorption coefficient (bone/blood) least absorption coeefficient |
Bone, blood |
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Thermal effects |
Decreased pain perception Decrease in joint stifffness Decrease muscle guarding Increase local blood flow |
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Non-thermal effects |
Wound management Protein synthesis bone repair soft tissue repair |
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Formation and accumulation of gas-filled bubbles caused by US |
Cavitation |
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bubbles may expand and contract to a smaller extent without bursting |
Stable cavitation |
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Violent collapse or implosion of gas bubble resulting in tissue destruction |
Unstable (transient) cavitation |
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unidirectional movement of a fluuid in a US field |
Acoustic streaming |
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2 types of acoustic streaming |
bulk streaming Microstreaming |
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movement of fluid that is visible when testing the output of ultrasound equipment and that can occur in any fluid being insonated. |
Bulk streaming |
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Very small or minute fluid movements around the cell |
Microstreaming |
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Alternate compression & relaxation of tissue by the pressure of sound waves and mechanical reactions of the tissue |
Micromassage |
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Peaks of high pressure; can cause transient cavitation |
Antinodes |
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No pressure; can cause stassis of blood |
Nodes |
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Solid medium which liquefies under the insonation |
Thixotropic agent |
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Ratio of the pulse length to the total treatment time |
Duty Cycle |
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Formula of Duty Cycle |
(on time/on time + off time) x 100 |
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Minimum and maximum duration |
1-2 mins 8 mins max 5 mins ave |
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(acute/chronic) longer treatment time is needed |
Chronic |
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Effects of US primarily before stretching of shortened tissue and reduction of pain |
Thermal effects |
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Effects of US primarily used for altering membrane permeability to accelerate tissue healing |
Non-thermal effects |
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Contraindications |
Acute infections or sepsis Pacemaker hemophilia |
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Precautions |
over a fracture Over a breast implant Metal implants |
