Ultrasound 1 Flashcards
Definition
High frequency mechanical waves
Non ionizing
Frequency
Therapeutic
Freq greater than 20,000 Hz
Therapeutic in PT = 1 MHz, 2MHz, or 3 MHz level
kHz Ultrasound
22.5, 25, 35, and 40
AKA low frequency ultrasound
Causes fragmentation of tissue
kHz Ultrasound - PT use
Used for wound debridement and to enhance tissue healing
Rehab Ultrasound Imaging (RUSI)
The use of ultrasound to evaluate muscle and soft tissue function during exercise and physical tasks
Used to assist in application of therapeutic interventions aimed at improving neuromuscular function
Diagnositc Ultrasound Unit - Pulser
2 to 15 MHz
Diagnositc Ultrasound Unit - Ultrasound Transducer
Delivers sound to tissue and receives the reflected energy
Array of crystals in either linear or curvilinear configuration
Diagnositc Ultrasound Unit - Scan converter
Changes signal from analog to digital, also apmlifies and adjusts the signal to noise ratio
Frequency
A wave - one cycle of a wave
From peak to peak
# of oscillations/sec of a molecule
Frequency and depth of penetration of the sound wave
The higher the f, the less depth
The lower the f, the deeper the sound wave will penetrate tissue
Inverse relationship
1 MHz travels deeper than 3 MHz
Wavelength
The distance between 2 successive peaks in a pressure wave
Wavelength time delay associated with
oscillation of molecules develops
Periods of condensation (compression)
Periods of rarefaction (less pressure going through)
Wavelength - vibration
Finite period of time from one molecule causing another molecule to vibrate
Phase shift
Molecules will vibrate asychnonously or be out of phase and the time delay s called phase shift
There is equal phase shift btw each of the successive molecules in sound propagation
Velocity
SPeed at which the vibratory motion moves through a substance
Velocity =
Frequency x Wavelength
The more rigid the material…
The greater the velocity
This feature is primarily used for diagnostic imagine
Air - velocity
air has a slow velocity - does not propgate sound almost at all
Amplitude
The higher the amplitude, the more energy that is being delivered
We measure amplitude with
power and intensity
Power
the total amount of energy from the transducer measured in Watts
Intensity
total divided by the effective radiating surface (ERA) measured ing watts/cm2
Intensity =
power/ERA
Ultrasound units
Give Watts as well as Watts/cm2
