Transducers and Physics Exam Flashcards
Ultrasound is sound above _________ kHz
20
What unit does Impedance use?
Rayls
What does PORN stand for in the world of Physics?
What does it mean?
Normal, perpendicular or orthogonal incidence – happens when the sound beam strikes a boundary between 2 media at exactly 90 degrees
Define Absorption. What percentage makes it a dominant factor in Attenuation?
- Absorption is the loss of sound energy secondary to its conversion to thermal energy.
- 80%
Describe the 3 types of reflectors & the reflection they produce.
- Specular—produces very smooth surfaced and mirror-like reflection
- Scattering- The random redirection of sound waves on multiple directions. It is produced when sound beam strikes a rough surface. Surface irregularities are same size or smaller than the wavelength.
- Backscatter – scatter returning in the same general direction as the transducer
_____________ is a material’s resistance to sound traveling through it.
Impedance
The diaphragm is an example of a ____________ reflector.
Specular
Posterior enhancement and through transmission are not the same thing, true or false?
FALSE they are the same thing
The loss of sound energy from absortion, scattering, and reflection is known as
Attenuation
Frequency and wavelength have what kind of a relationship?
Inverse
Ultrasound is what type of a wave?
Longitudinal
A structure that has nearly the same echo characteristics and echogenicity of a second structure is said to be _________ to the second structure.
Isoechoic
What type of ultrasound is required to form an image?
Pulsed Wave
What probe do we usually use for vascular or small parts?
Linear
Why must we never sterilize an ultrasound transducer? What will happen to it?
We must not sterilize our transducers because it will lose its piezoelectic properties
