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WorksheetsTest 1 - DS 4351 Review Ch 12, 13 (Doppler Physics)
Total questions: 40
Worksheet time: 20mins
Which of the images will result in the most significant decrease in temporal resolution
A
B
C
D
Which of the following transducers creates a sector image shape?
Linear sequential array
Phased array
Annular phased array
B & C
Dynamic receive focusing uses
Mechanical means to focus the beam
Time delays to excite array elements
Variable number of elements to form the transmitted beam
Optimal time delays depend upon the depth at which the reflection was created
What is the main advantage of high line density
More pulses per line
Shorter T
Improved spatial resolution
Longer frame rate
Which of the following is consistent with improved temporal resolution
Color Doppler
Higher Frame rate
More gray shades
More detail
How does the number of pulses needed to create an image affect temporal resolution
They are directly related
They are indirectly related
They are inversely related
They are not related
Reducing the sector angle of a phased array (with no other change), will result in:
An increase in the frame rate
A larger imaged field
Worse temporal resolution
Frame rate will note chage
Which of the following actions would not lead to a decrease in the image frame rate of a phased array scanner?
Increase the image depth setting
Increase the number of transmit focal zones
Increase the width of the image sector
Increase the transmit power to the transducer
Which of the following factors do not affect the number of pulses needed to create an image
Line density
Multi focus vs single focus
Sector size
None of the above
Some sector scanners provide the capability to reduce the imaged field sector angle. The main advantage of this operation is
It allows the use of higher frequencies
A small sector angle offers a higher frame rate
A smaller sector improves the dynamic range
It enables increased acoustical power in the patient
The transducer you are using is a Linear Phased Array assembly. What is an advantage of this type of transducer?
Not all elements are excited to create a single pulse
Enables mechanical steering
Produces very long pulses for improved axial resolution
Enables electronic focusing and steering
Which of the following will result in the best spatial resolution?
A
C
B
D
For a (modern) linear array transducer, what method of focusing is used to focus the beam?
Transmit focusing
Dynamic receive focusing
Aperture focusing
Electronically focusing
What is the main advantage of high line density?
Improve spatial resolution
Lateral resolution is degraded
Frame rate increases
Rate of attenuation is increased
Which of the following statements describes a linear phased array transducer?
Electronically focused in two dimensions and mechanically steered
Electronically focused along the length of the array and electronically steered
Electronically focused along the width of the array, mechanically focused along the length of the array, and unsteered
Electronically focused along the width of the array, mechanically focused along the length of the array, and mechanically steered
Which of the images has better temporal resolution
A
B
C
D
What is the fundamental limitation of temporal resolution
imaging depth
speed of sound in the miedum
line density
sector size
How is beam steering done by a linear phased array transducer?
A single, separate channel is used for each beam
All elements are excited; time delays control the beam direction
A motor inside the transducer housing oscillates the array
Groups of elements are excited separately; the active group position determines the beam direction
Which type of transducer will decrease the slice thickness of the beam?
A linear array with multiple rows of elements
Phased array with a small footprint
Curved array with a steep curvature
Phased linear array
An advantage obtained when the sector field of a phased array B mode scanner is reduced is a higher
Dynamic range
Frame rate
Output power
Ultrasound frequency
If three transmit focal zones are applied rather than one zone, the maximum frame rate will
Decrease
Remain unchanged
Double
Triple
If you wish to produce a sonogram in a rectangular format, which transducer should you choose?
Annular array
Linear array
Phased array
Convex array
Electronic focusing in the transmit mode is accomplished using
Curved crystal elements
Changeable lens
Time delays to excite crystal elements
Time delays after receiving the signals so they will be in phase when summed
What type of resolution is affected most by pulse duration?
Lateral resolution
Contrast resolution
Temporal resolution
Axial resolution
Varying the excitation voltage to each crystal in the group, used to reduce side lobes artifacts is called:
Apodization
Dynamic aperture
Subdicing
Rectification
Which statement is not true about Linear sequential array transducer?
Rectangular footprint
All crystals are fired simultaneously
Sound beam are parallel to each other
Beam is focusing using electronic phase delays
The sound beam can be focused by all of the following except
Dynamic aperture
Acoustic lens
Curved crystal
Matching layer
Which statement is not true regarding lateral resolution?
It is equal to beam width
It remains constant throughout scanning depth
It is defined as the minimum separation required to resolve two structures perpendicular to the beam axis
It is improved when beams line density is high
How does imaging depth affect temporal resolution
They are directly related
They are indirectly related
They are inversely related
They are not related
Which of the following describe the grating lobes?
Apodization can reduce the grating lobes
Created by array transducers
Degrade lateral resolution and reduce image quality
All of the above
What type of focusing decreases the frame rate?
Mechanical focusing
Dynamic receive focusing
Dynamic aperture focusing
Multiple transmit focusing
What is the main advantage of multiple focal zones
Better lateral resolution
One pulse per scan line
Higher frame rate
Better temporal resolution
A linear sequential array transducer has 128 crystals. How many of these crystals are fired to create a single sound beam?
1
a small group
a large group
128
Which of the following statements is correct :
Spatial resolution improves with multi-focusing
Spatial resolution degrades with high line density
Lateral resolution degrades with dynamic aperture
Spatial resolution improves with high frame rate
The ultrasound system in your lab has a transducer with a small footprint. This kind of transducer has the following disadvantage?
It is too large to use for intercostal scanning
You cannot image an area larger than the footprint
The near field lateral resolution is poor
Focusing degrades at a depth of twice the transducer aperture
Apodization is a method employed to
Beam steering
External focusing
Reduce side lobes
Reduce beam width in the Z axis
What should you do to obtain the best lateral resolution for a given transducer?
Use the maximum acoustic power
Use the lowest frequency in the bandwidth
Use the maximum number of focal zones
Use the minimum scanning depth
A linear phased array transducer has 128 crystals. How many of these crystals are fired to create a single sound beam?
1
a small group
a large group
128
You are reviewing an ultrasound image that has a sector display format with a pointed top. What kind of transducer was used to acquire this image?
Linear array
Phased array
Curved array
Annular phased linear array
The term for a transducer that has an array of rectangular elements arranged in a straight line is
Annular array
Linear array
Curved array
Convex sequenced array
