ultrasound Flashcards
What is therapeutic ultrasound
A type of sound wave
Frequency greater than 20,000
Exceeds normal human limit
What is the piezoelectric crystal on the wand
It is smaller than the sound head, also known as the effective radiating area
With no current flow what is the Shape of piezoelectric crystal
With no current flow, crystal shape remains unchanged
With a negative current what is the shape of the piezoelectric crystal
Concave or convex
With a positive current flow what is the shape of the piezoelectric crystal
Change I’m shape occurs as the direct chin if flow across the crystal alternates
What is attenuation
The decrease in ultrasound intensity as ultrasound travels through tissue
What does thermal ultrasound do
Incresse in tissue temperature
Continuous ultrasound
What is non thermal ultrasound
Acoustic streaming
Microstreaming
Cavitation
Pulse ultrasound
What are thermal effects of us
Acceleration of metabolic rate
Reduce of control pain
Alteration of nerve conduction
Increased circulation
Increased soft tissue extensibility
T/f tissues with higher absorption coefficients generally have hugger collagen contents
True
T/f speed doeS NOT affect temperature change
True
What are four factors that affect temperature change
Time
Frequency
Intensity
Duration
What is cavitation
The formation, growth, and pulsation of gas filled bubbles caused by ultrasound
What is microstreaming
Micro scale eddying that occurs near any small vibrating object
What is acoustic streaming
The steady circular flow of cellular fluids imduced by ultrasound
