Ultrasound Interactions And Attenuation Flashcards
It is also called as tissue interface
Acoustic boyndaries
It is the position within tissue where the values of acoustic impedance change
Acoustic boundaries
Weakening of the sound as it propagates tohrough the medium.
Attenuation
It results to reduction in amplitude and intensity as sound travels.
Attenuation
In terms of attenuation:
When tissue is densely packed, attenuation will be much _______?
Greater than less densely packed tissue
In terms of attenuation:
When the path length increases, attenuation will _______?
Also increase
In terms of attenuation:
Higher frequencies are more attenuated lower frequencies. True or false?
True
In terms of attenuation:
Is it true that lower frequencies penetrate more deeply than higher frequencies because theybare attenuated to a higher degree?
No. lesser frequencies penetrate more deeply bc they are ATTENUATED TO A LESSER DEGREE.
Attenuation that occurs with eache centimeter the sound wave travels.
Attenuation Coefficient (Ac)
What is the typical value for attenuation coefficient of a soft tissue?
0.5 dB/cm
What are the 5 main processes that causes attenuation?
Absorption Scattering Reflection Refraction Divergence
The process by whichenergy in the uts beam is transferred to the propagating tissue
Absorption
It is the dominant factor in controlling attenuation
Absorption
What will happen to the intensit if the ultrasound beam that travels through a medium diverge?
Reduction of intensity
The rate of divergence depends on what?
Diameter of source
It is the major interaction of interest in diagnostic ultrasound
Reflection
It occurs when two large structures of significantly different acoustic impedance form an interface
Reflection
It is the sound that hits the acoustic interface
Incident energy
It is the reflected beam
Echo
What will be the refelctions at boundaries between soft tissue?
Small echoes
What will be the reflection if the medium is air/gas?
Very large echoes
What will be the reflection if the medium is bone?
Large echoes
