DAVIES SPI: II. Physical Principles (20%
of ARDMS)
What interaction of ultrasound and tissue is primarily responsible for imaging the
internal structure of organs?
A. Specular reflection
B. Refraction
C. Diffraction
D. Destructive interference
E. Scattering - Correct Answer-E. Scattering
Bandwidth refers to:
A. Number of cycles per pulse
B. Range of frequencies in a pulse
C. Rate of pulse repetition frequency
D. Range of pulses in a frame
E. Number of wavelengths in one second - Correct Answer-B. Range of frequencies in a
pulse
Acoustic impedance:
A. Is independent of the speed of sound
B. Is inversely proportional to the density
C. Is greater in gas than in metal
D. Equals density times the propagation speed
E. Is independent of the density - Correct Answer-D. Equals density times the
propagation speed
< Z=rc >
You have increased the transmit power while performing a pelvic ultrasound
examination. This action increases which of the following?
A. Penetration
B. Acoustic power
C. Image brightness
D. Voltage applied to the transducer elements
E. All of the above - Correct Answer-E. All of the above
Attenuation of the sound beam increases with increasing:
,A. Path length
B. Absorption
C. Frequency
D. Scattering and reflection
E. All of the above - Correct Answer-E. All of the above
<The attenuation coefficient is the degree of attenuation for each centimeter of sound
propagation. Anything that increases attenuation will increase the attenuation
coefficient>
Which prefix equals 10^(-3)?
A. Micro
B. Milli
C. Mega
D. Centi
E. None of the above - Correct Answer-B. Milli
<Micro is 10^(-6), mega is 10^6, and centi is 10^(-2)>
You are imaging with a 5 MHz linear array transducer. What sound parameter stays
constant as the beam propagates through the tissue?
A. Frequency
B. Intensity
C. Amplitude
D. Wavelength
E. None of the above - Correct Answer-E. None of the above
<As sound propagates through tissue, high frequencies are attenuated more rapidly
than low frequencies. This results in a shifting toward the lower frequencies in the
transmitted bandwidth with increasing depth. The intensity and amplitude of the beam
decrease as a result of attenuation. The wavelength is altered with the downshifting of
the overall frequency bandwidth>
The time that it takes for one pulse to occur is known as the:
A. Duty factor
B. Spatial pulse length
C. Wavelength
D. Pulse repetition frequency
E. Pulse duration - Correct Answer-E. Pulse duration
Which statement about the two pulse trains displayed below is true? Each represents a
signal vs time.
,A. A has a lower frequency than B
B. B has a longer period than A
C. A has a shorter wavelength than B
D. A has a better axial resolution than B
E. A has a shorter spatial pulse length than B
Image A: radio waves
Image B: gamma rays - Correct Answer-A. A has a lower frequency than B
<Period is the time it takes one complete cycle to occur. A's period is longer than B's.
The pulse train with the shortest wavelength would have the highest frequency, which
again is B. The shortest pulse (B) will produce the better axial resolution. The longest
pulse (A) produces the greatest spatial pulse length>
In order to display a structure on your sonographic image the sound beam must be
reflected at the interface. What is required for sound reflection at the interface of two
structures?
A. Oblique incidence at the interface boundary
B. Temperature differences between the two media
C. A difference in the acoustic impedance of the media
D. Different media diameters
E. Different attenuation coefficients - Correct Answer-C. A difference in the acoustic
impedance of the media
You notice that the image in the far field is less bright compared to the near field. This is
due to:
A. Sound attenuation
B. Propagation speed variation
C. Refraction
D. Diffraction
E. The Doppler effect - Correct Answer-A. Sound attenuation
<As sound propagates through tissue, the beam strength is weakened through
absorption, reflection, and other interactions with the medium. This weakening of beam
strength is termed attenuation and accounts for decreased brightness of the image in
the far filed compared to the near field>
The mass you are imaging has a diameter of 35mm. This value can also be expressed
as:
A. 350 cm
B. 0.35 cm
C. 3.5 cm
, D. 35 m
E. 3.5 m - Correct Answer-C. 3.5 cm
When you image a structure that is a specular reflector, the strength of the received
signal depends on the following two factors:
A. Difference in acoustic impedance and angle of incidence
B. Difference in acoustic velocity and interface size
C. Difference in acoustic velocity and motion of reflector
D. Angle of incidence and tissue temperature
E. Bulk modulus and interface size - Correct Answer-A. Difference in acoustic
impedance and angle of incidence
<The amplitude of the reflected signal depends on the difference in acoustic impedance
between the two tissues. The greater the difference, the greater the reflection. As
mentioned previously, specular reflection is highly angle-dependent. If the beam strikes
the interface at a right angle, the reflected energy will be directed back to the
transducer. But if the beam strikes the interface at another angle, the reflected energy
will be directed at the same angle AWAY from the transducer>
A longitudinal wave is characterized by:
A. A wave that demonstrates only sagittal imaging planes
B. Randomized particle motion
C. A constant acoustic velocity of 1540 m/s
D. Particle motion occurring in the same direction as propagation
E. Particle motion occurring perpendicular to the direction of propagation - Correct
Answer-D. Particle motion occurring in the same direction as propagation
<Particle motion that is perpendicular to the direction of propagation characterizes a
transverse wave>
Which of the following increases as frequency increases?
A. Absorption
B. Scattering
C. Attenuation
D. A and C only
E. All of the above - Correct Answer-E. All of the above
What two conditions must be present to cause refraction of a sound wave?
A. Perpendicular incidence and identical media propagation speeds
B. Perpendicular incidence and reflector size smaller than one wavelength
C. Oblique incidence and different media propagation speeds
D. Oblique incidence and reflector size smaller than one wavelength
of ARDMS)
What interaction of ultrasound and tissue is primarily responsible for imaging the
internal structure of organs?
A. Specular reflection
B. Refraction
C. Diffraction
D. Destructive interference
E. Scattering - Correct Answer-E. Scattering
Bandwidth refers to:
A. Number of cycles per pulse
B. Range of frequencies in a pulse
C. Rate of pulse repetition frequency
D. Range of pulses in a frame
E. Number of wavelengths in one second - Correct Answer-B. Range of frequencies in a
pulse
Acoustic impedance:
A. Is independent of the speed of sound
B. Is inversely proportional to the density
C. Is greater in gas than in metal
D. Equals density times the propagation speed
E. Is independent of the density - Correct Answer-D. Equals density times the
propagation speed
< Z=rc >
You have increased the transmit power while performing a pelvic ultrasound
examination. This action increases which of the following?
A. Penetration
B. Acoustic power
C. Image brightness
D. Voltage applied to the transducer elements
E. All of the above - Correct Answer-E. All of the above
Attenuation of the sound beam increases with increasing:
,A. Path length
B. Absorption
C. Frequency
D. Scattering and reflection
E. All of the above - Correct Answer-E. All of the above
<The attenuation coefficient is the degree of attenuation for each centimeter of sound
propagation. Anything that increases attenuation will increase the attenuation
coefficient>
Which prefix equals 10^(-3)?
A. Micro
B. Milli
C. Mega
D. Centi
E. None of the above - Correct Answer-B. Milli
<Micro is 10^(-6), mega is 10^6, and centi is 10^(-2)>
You are imaging with a 5 MHz linear array transducer. What sound parameter stays
constant as the beam propagates through the tissue?
A. Frequency
B. Intensity
C. Amplitude
D. Wavelength
E. None of the above - Correct Answer-E. None of the above
<As sound propagates through tissue, high frequencies are attenuated more rapidly
than low frequencies. This results in a shifting toward the lower frequencies in the
transmitted bandwidth with increasing depth. The intensity and amplitude of the beam
decrease as a result of attenuation. The wavelength is altered with the downshifting of
the overall frequency bandwidth>
The time that it takes for one pulse to occur is known as the:
A. Duty factor
B. Spatial pulse length
C. Wavelength
D. Pulse repetition frequency
E. Pulse duration - Correct Answer-E. Pulse duration
Which statement about the two pulse trains displayed below is true? Each represents a
signal vs time.
,A. A has a lower frequency than B
B. B has a longer period than A
C. A has a shorter wavelength than B
D. A has a better axial resolution than B
E. A has a shorter spatial pulse length than B
Image A: radio waves
Image B: gamma rays - Correct Answer-A. A has a lower frequency than B
<Period is the time it takes one complete cycle to occur. A's period is longer than B's.
The pulse train with the shortest wavelength would have the highest frequency, which
again is B. The shortest pulse (B) will produce the better axial resolution. The longest
pulse (A) produces the greatest spatial pulse length>
In order to display a structure on your sonographic image the sound beam must be
reflected at the interface. What is required for sound reflection at the interface of two
structures?
A. Oblique incidence at the interface boundary
B. Temperature differences between the two media
C. A difference in the acoustic impedance of the media
D. Different media diameters
E. Different attenuation coefficients - Correct Answer-C. A difference in the acoustic
impedance of the media
You notice that the image in the far field is less bright compared to the near field. This is
due to:
A. Sound attenuation
B. Propagation speed variation
C. Refraction
D. Diffraction
E. The Doppler effect - Correct Answer-A. Sound attenuation
<As sound propagates through tissue, the beam strength is weakened through
absorption, reflection, and other interactions with the medium. This weakening of beam
strength is termed attenuation and accounts for decreased brightness of the image in
the far filed compared to the near field>
The mass you are imaging has a diameter of 35mm. This value can also be expressed
as:
A. 350 cm
B. 0.35 cm
C. 3.5 cm
, D. 35 m
E. 3.5 m - Correct Answer-C. 3.5 cm
When you image a structure that is a specular reflector, the strength of the received
signal depends on the following two factors:
A. Difference in acoustic impedance and angle of incidence
B. Difference in acoustic velocity and interface size
C. Difference in acoustic velocity and motion of reflector
D. Angle of incidence and tissue temperature
E. Bulk modulus and interface size - Correct Answer-A. Difference in acoustic
impedance and angle of incidence
<The amplitude of the reflected signal depends on the difference in acoustic impedance
between the two tissues. The greater the difference, the greater the reflection. As
mentioned previously, specular reflection is highly angle-dependent. If the beam strikes
the interface at a right angle, the reflected energy will be directed back to the
transducer. But if the beam strikes the interface at another angle, the reflected energy
will be directed at the same angle AWAY from the transducer>
A longitudinal wave is characterized by:
A. A wave that demonstrates only sagittal imaging planes
B. Randomized particle motion
C. A constant acoustic velocity of 1540 m/s
D. Particle motion occurring in the same direction as propagation
E. Particle motion occurring perpendicular to the direction of propagation - Correct
Answer-D. Particle motion occurring in the same direction as propagation
<Particle motion that is perpendicular to the direction of propagation characterizes a
transverse wave>
Which of the following increases as frequency increases?
A. Absorption
B. Scattering
C. Attenuation
D. A and C only
E. All of the above - Correct Answer-E. All of the above
What two conditions must be present to cause refraction of a sound wave?
A. Perpendicular incidence and identical media propagation speeds
B. Perpendicular incidence and reflector size smaller than one wavelength
C. Oblique incidence and different media propagation speeds
D. Oblique incidence and reflector size smaller than one wavelength
