Please select all that apply What causes reflection of an ultrasound wave at an
ID: 2268249 • Letter: P
Question
Please select all that apply
What causes reflection of an ultrasound wave at an interface: a. a mismatch of speed of sound b. a mismatch of acoustic impedance c. an angle of incidence different than 90 degrees d. both a. and b.
(1pt)-Scattering of ultrasound waves: a. occurs when the surface of the reflector is not smooth b. is random noise c. reduces the energy of the ultrasonic signal d. is the primary source of signal from the human body e. is angle dependent
(1pt)-Speckle in ultrasound images: a. is due to electronic noise b. is due to the constructive and destructive interference of the scattered waves c. depends on the spatial resolution of the system
(1pt)-Piezoelectric transducers: a. convert voltage into pressure b. convert pressure into voltage c. can only be used as single element transducers d. can be used to form arrays
Phased arrays: a. allow electronic beam focusing b. have worse spatial resolution than single element trasnducers c. have better spatial resolution than single element transducers d. have higher frequency than single element transducers e. are more expensive than single element trasducers
Which of the following are “standard ultrasound imaging” methods? a. B-mode b. Doppler imaging c. 3D imaging d. HIFU
Explanation / Answer
(a)due to variation of impedances Scattering of ultrasound waves: a. occurs when the surface of the reflector is not smooth b. is random noise , is the primary source of signal from the human body e. is angle dependent speckle is due to the constructive and destructive interference of the scattered waves Piezoelectric transducers convert voltage into pressure,can be used to form arrays Phased arrays: a. allow electronic beam focusinghave better spatial resolution than single element transducers d. have higher frequency than single element transducers e. are more expensive than single element trasducers “standard ultrasound imaging” methods? a. B-mode b. Doppler imaging c. 3D imaging
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