Ultrasound Physics Exam 1 UPDATED ACTUAL QUESTIONS
AND CORRECT Answers
Energy (E) Ability to do work
Amplitude Maximum or minimum acoustic variation of wave
Strength of wave
Power Rate at which energy is transferred
Intensity Energy per unit area
Absorption Conversion of sound energy into heat
Velocity Speed of sound wave
Attenuation Coefficient Rate at which sound is attenuated per unit depth
Total Attenuation Formula Total Attenuation (dB) = dB/cm-MHz x cm (depth) x MHz (tx freq)
Acoustic Interface Border between two mediums with differing acoustic impedances
Angle of Incidence (Θi) Angle at which sound hits a reflector
Angle of Reflection (Θr) Angle at which sound bounces off a reflector
Angle of Transmission (Θt) Angle at which sound is bent after passing through a reflector
Reflection Portion of sound that returns to TX
Echo
, Refraction Bending of sound as it passes through an interface
Refraction Requires... Oblique incidence
Different propagation speeds of mediums
Acoustic Impedance (Z) Determines how easily mechanical waves can travel through a medium
Determined by the medium
If acoustic impedances are the same between two Transmitted
mediums, sound will be...
If acoustic impedances are different between two Reflected at the interface
mediums, sound will be...
Relationship between acoustic impedance, propagation Directly proportional
speed, and density
Rayl Unit of acoustic impedance
kg/m^2/sec
Structures with a higher density will have a ______ Z Higher
value
Structures with a lower density will have a ______ Z Lower
value
If the difference in Z values is small... There will be a small reflection
If the difference in Z values is big... There will be a big reflection
Scattering Sound waves go in all directions
Interface is shorter than 1 wavelength
Makes up parenchyma of most organs
Raleigh Scattering Small scattering reflectors
Normal Incidence Sound is directed at 90º
Maximum detection of reflected beams
Oblique Incidence Sound is directed at anything other than 90º
Θi = Θr
Greater chance of transmission with bone-soft tissue interfaces
Specular Reflection Occurs at 90º with a specular reflector
Interface is larger than 1 wavelength
Does refraction occur with normal incidence? NO
AND CORRECT Answers
Energy (E) Ability to do work
Amplitude Maximum or minimum acoustic variation of wave
Strength of wave
Power Rate at which energy is transferred
Intensity Energy per unit area
Absorption Conversion of sound energy into heat
Velocity Speed of sound wave
Attenuation Coefficient Rate at which sound is attenuated per unit depth
Total Attenuation Formula Total Attenuation (dB) = dB/cm-MHz x cm (depth) x MHz (tx freq)
Acoustic Interface Border between two mediums with differing acoustic impedances
Angle of Incidence (Θi) Angle at which sound hits a reflector
Angle of Reflection (Θr) Angle at which sound bounces off a reflector
Angle of Transmission (Θt) Angle at which sound is bent after passing through a reflector
Reflection Portion of sound that returns to TX
Echo
, Refraction Bending of sound as it passes through an interface
Refraction Requires... Oblique incidence
Different propagation speeds of mediums
Acoustic Impedance (Z) Determines how easily mechanical waves can travel through a medium
Determined by the medium
If acoustic impedances are the same between two Transmitted
mediums, sound will be...
If acoustic impedances are different between two Reflected at the interface
mediums, sound will be...
Relationship between acoustic impedance, propagation Directly proportional
speed, and density
Rayl Unit of acoustic impedance
kg/m^2/sec
Structures with a higher density will have a ______ Z Higher
value
Structures with a lower density will have a ______ Z Lower
value
If the difference in Z values is small... There will be a small reflection
If the difference in Z values is big... There will be a big reflection
Scattering Sound waves go in all directions
Interface is shorter than 1 wavelength
Makes up parenchyma of most organs
Raleigh Scattering Small scattering reflectors
Normal Incidence Sound is directed at 90º
Maximum detection of reflected beams
Oblique Incidence Sound is directed at anything other than 90º
Θi = Θr
Greater chance of transmission with bone-soft tissue interfaces
Specular Reflection Occurs at 90º with a specular reflector
Interface is larger than 1 wavelength
Does refraction occur with normal incidence? NO
