3. Transducers Flashcards
A transducer converts one form of _______ to another.
a. energy
b. force
c. image
d. scan
a. energy
Ultrasound transducers convert ______ energy into ________ energy, and vice versa.
a. electric, light
b. heat, electric
c. heat, light
d. electric, ultrasound
d. electric, ultrasound
Ultrasound transducers operate on the _______ principle.
a. piezomagnetic
b. piezoelectric
c. electropiezo
d. electromagnetic
b. piezoelectric
Single-element transducers are in the form of ________.
a. squares
b. rectangles
c. disks
d. ovals
c. disks
The _______ of a transducer element changes when voltage is applied to its faces.
a. width
b. height
c. length
d. thickness
d. thickness
The term transducer is used to refer to a transducer ______ or to a transducer _______.
a. element, assembly
b. matching, element
c. backing, damping
d. backing, assembly
a. element, assembly
A transducer ______ is part of a transducer ________.
a. assembly, element
b. element, assembly
c. cable, matching
d. backing, damping
b. element, assembly
An electric voltage pulse, when applied to a transducer, produces an ultrasound _________ of a(n) _________ that is equal to that of the voltage pulse.
a. pulse, amplitude
b. intensity, amplitude
c. pulse, frequency
d. pulse, duration
c. pulse, frequency
The resonance frequency of an element is determined by its _______.
a. width
b. height
c. length
d. thickness
d. thickness
Operating frequency ______ when transducer element thickness is increased.
a. increases
b. decreases
c. is unchanged
d. none of the above
b. decreases
The addition of damping material to a transducer reduces the number of ________ in the pulse, thus improving ______ ________. It increases _______.
a. amplitudes, detail resolution, frequency
b. amplitudes, lateral resolution, bandwidth
c. cycles, lateral resolution, frequency
d. cycles, axial resolution, bandwidth
d. cycles, axial resolution, bandwidth
Damping material reduces the ______ of the transducer and
_______ of the diagnostic system.
a. efficiency, sensitivity
b. frequency, sensitivity
c. frequency, efficiency
d. frequency, penetration
a. efficiency, sensitivity
Ultrasound transducers typically generate pulses of ________ or ______ cycles.
a. five, ten
b. five, six
c. one, three
d. two, three
d. two, three
For a particular transducer element material, if a thickness of 0.4 mm yields an operating frequency of 5 MHz, the thickness required for an operating frequency of 10 MHz is _____ mm.
a. 0.1
b. 0.2
c. 0.3
d. 0.5
b. 0.2
Which of the following transducer frequencies would have the thinnest elements?
a. 2 MHz
b. 3 MHz
c. 5 MHz
d. 7 MHz
e. 10 MHz
e. 10 MHz
The matching layer on the transducer surfaces reduces ________ caused by impedance differences.
a. attenuation
b. amplitude
c. transmission
d. reflection
d. reflection
A coupling medium on the skin surface eliminates reflection caused by ________.
a. air
b. skin
c. matching layer
d. element
a. air
Damping lengthens the pulse. T or F?
False
Damping increases efficiency. T or F?
False
The damping layer is in the front or the back of the element?
Back
The matching layer is in front or back of the element?
Front
The matching layer has _______ impedance.
a. high
b. low
c. intermediate
d. zero
c. intermediate
Elements in linear arrays are in the form of _________.
a. rectangles
b. squares
c. rings
d. disks
a. rectangles
Transducer assemblies are also called _________.
a. transducers
b. probes
c. scanheads
d. scan convertors
e. skinheads
f. more than one of the above
f. more than one of the above (transducers, probes, scanheads)
Operating frequency is also called _______ _______.
a. operating mode
b. bandwidth mode
c. operating bandwidth
d. resonance frequency
d. resonance frequency
Mixtures of a piezoelectric ceramic and a nonpiezoelectric polymer are called __________.
a. composites
b. piezopolymers
c. ceramopolymers
d. piezocomposites
a. composites
To operate a transducer at more than one frequency requires ___________.
a. narrow bandwidth
b. moderate bandwidth
c. broad bandwidth
d. no bandwidth
c. broad bandwidth
Is it practical to attempt to operate a 5 MHz transducer with a bandwidth of 1 MHz at 6 MHz?
No, because these frequencies are outside the bandwidth (4.5 to 5.5 MHz)
The region between the transducer and the focal region is the ______ length.
a. narrow zone
b. near zone
c. wide zone
d. far zone
b. near zone
Transducer size is also called ________.
a. aperature
b. zone
c. bandwidth
d. width
a. aperature
Near zone length increases with increasing source ________ and _________.
a. amplitude, intensity
b. amplitude, frequency
c. aperture, frequency
d. aperature, amplitude
c. aperature, frequency
Which transducer element has the longest near zone?
a. 6 mm, 5 MHz
b. 6 mm, 7 MHz
c. 8 mm, 7 MHz
c. 6 mm, 7 MHz
A higher-frequency transducer produces a ______ near-zone length.
a. longer
b. shorter
c. unchanged
d. none of the above
a. longer
A smaller aperature produces a(n) _________ near zone length.
a. longer
b. shorter
c. unchanged
d. none of the above
b. shorter
A transducer with a near zone length of 10 cm can be focused at 12 cm. T or F?
False (can focus only in the near zone)
Which of the following transducer(s) can focus at 6 cm?
a. 5 MHz, NZL 5 cm
b. 4 MHz, NZL 6 cm
c. 4 MHz, NZL 10 cm
d. b and c
e. none of the above
c. 4 MHz, NZL 10 cm
Sound may be focused by using a _________.
a. curved element
b. lens
c. phased array
d. more than one of the above
d. (all of the above)
Focusing reduces the beam diameter at all distances from the transducer. T or F?
False
The distance from a transducer to the location of the narrowest beam width produced by a focused transducer is called focal _______.
a. length
b. width
c. depth
d. height
a. length
Transducer arrays are transducer assemblies with several transducer _________.
a. elements
b. layers
c. cables
d. backings
a. elements
Linear arrays scan beams _________ element groups.
a. phasing
b. steering
c. delaying
d. sequencing
d. sequencing
A phased linear array with a single line of elements can focus in ________ dimension(s).
a. one
b. two
c. three
d. five
a. one (the lateral dimension in the scan plane)
Focusing in section thickness can be accomplished with ________ elements or a _______.
a. curved, sequencer
b. round, sequencer
c. curved, lens
d. round, lens
c. curved, lens
Electronic focusing in section thickness requires multiple rows of _______.
a. lenses
b. matchers
c. dampers
d. elements
d. elements
If the elements of a phased array are pulsed in rapid succession from right to left, the resulting beam is ________.
a. steered right
b. steered left
c. focused
b. steered left
If the elements of a phased array are pulsed in rapid succession from outside in, the resulting beam is ________.
a. steered right
b. steered left
c. focused
c. focused
_________ and __________ describe how arrays are constructed (select two).
a. linear
b. phased
c. sequenced
d. vector
e. convex
a. linear and e. convex
_____, ______, and _______ describe how arrays are operated (select three).
a. linear
b. phased
c. sequenced
d. vector
e. convex
b. phased, c. sequenced, d. vector
Shorter time delays between elements fired from outside result in ______ curvature in the emitted pulse and a ________ focus.
a. no, weak
b. less, shallower
c. less, deeper
d. greater, shallower
e. greater, deeper
c. less, deeper
A sector image is a result of sector steering of the beam. This means that pulses travel in ________ direction(s) from a common ____ at the transducer face.
a. two different, end
b. different, origin
c. the same, point
d. the same, end
b. different, origin
In ______ and ______ arrays, pulses travel out in different directions from different starting points on the transducer face.
a. linear, convex
b. convex, phased
c. phased, vector
d. convex, vector
d. convex, vector
Axial resolution is the min. reflector separation required along the direction of the ______ _______ to produce separate _____.
a. scan lines, echoes
b. sound travel, amplitudes
c. double reflectors, lines
d. scan lines, amplitudes
a. scan lines, echoes
Axial resolution depends directly on _________
a. the peak amplitude
b. spatial echo distance
c. spatial pulse length
d. spatial pulse width
c. spatial pulse length
Smaller axial resolution is better. T or F?
True
If there are three cycles of a 1 mm wavelength in a pulse, the axial resolution is _____ mm.
a. 1.0
b. 1.5
c. 2.5
d. 3.0
b. 1.5
For pulses traveling through soft tissue in which the frequency is 3 MHz and there are four cycles per pulse, the axial resolution is ___ mm.
a. 1.0
b. 1.5
c. 2.5
d. 3.0
a. 1.0
If there are two cycles per pulse, the axial resolution is equal to the ____. At 5 MHz in soft tissue, this is ____ mm.
a. wavelength, 5.0
b. wavelength, 0.3
c. duration, 1.54
d. duration, 0.2
b. wavelength, 0.3
Doubling the frequency causes axial resolution to be ______.
a. doubled
b. increased
c. degraded
d. halved
d. halved
Doubling the number of cycles per pulse causes axial resolution to be ____.
a. doubled
b. increased
c. degraded
d. halved
a. doubled
When studying an obese subject, a higher frequency likely will be required. T or F?
False
If better resolution is desired, a lower frequency will help. T or F?
False
If frequencies less than ___ MHz are used, axial resolution is not sufficient.
a. 0.1
b. 2
c. 5
d. 20
b. 2
If frequencies higher than ___ MHz are used, penetration is not sufficient for most applications.
a. 0.1
b. 2
c. 5
d. 20
d. 20
Increasing frequency improves resolution because ____ is increased.
a. reflection
b. heating
c. speed
d. attenuation
d. attenuation
Lateral resolution is the minimum ____ between two reflectors at the same depth such that when a beam is scanned across them, two separate _______ produced.
a. separation, propagations
b. amplitude, propagations
c. separation, echoes
d. amplitude, echoes
c. separation, echoes
Lateral resolution is equal to ______ ________ in the scan plane.
a. beam width
b. pulse length
c. beam length
d. pulse height
a. beam width
Lateral resolution does not depend on _______.
a. frequency
b. aperture
c. phasing
d. depth
e. damping
e. damping
For an aperture of a given size, increasing frequency improves lateral resolution. T or F?
True
Lateral resolution varies with distance from the transducer. T or F?
True
For a given frequency, a smaller aperture always yields improved lateral resolution. T or F?
False, in general (only true near the transducer)
Lateral resolution is determined by _______. (There is more than one correct answer)
a. damping
b. frequency
c. aperture
d. number of cycles in the pulse
e. distance from the transducer
f. focusing
b. frequency, c. aperture, e. distance from the transducer, f. focusing
Which of the following improve sound transmission from the transducer element into the tissue? (more than one correct answer)
a. matching layer
b. Doppler effect
c. damping material
d. coupling medium
e. refraction
a. matching layer, d. coupling medium
Lateral resolution is improved by ______.
a. damping
b. pulsing
c. focusing
d. matching
e. absorbing
c. focusing
For an unfocused transducer, the best lateral resolution is ______ the transducer width. This value of lateral resolution is found at a distance from the transducer face that is equal to the ____ ____ length.
a. equal to, near zone
b. half, near zone
c. equal to, far zone
d. half, far zone
b. half, near zone
An unfocused 3.5 MHz, 13 mm transducer will yield a minimum beam width of ___ mm.
a. 3.5
b. 13
c. 26
d. 6.5
d. 6.5 (frequency not needed)
An unfocused 3.5 MHz, 13 mm transducer produces three-cycle pulses. The axial resolution in soft tissue is ___ mm.
a. 0.7
b. 1.4
c. 13
d. 26
a. 0.7 (size not needed)
Axial resolution is often not as good as lateral resolution in diagnostic ultrasound. T or F?
False
The two resolutions may be comparable in the ____ region of a strongly focused beam.
a. near
b. far
c. local
d. focal
d. focal
Beam diameter may be reduced in the near zone by focusing. T or F?
True
Beam diameter may be reduced in the far zone by focusing. T or F?
False
The principle on which ultrasound transducers operate is the _____ .
a. Doppler effect
b. acousto-optic effect
c. acoustoelectric effect
d. cause and effect
e. piezoelectric effect
e. piezoelectric effect
Which of the following is not decreased by damping?
a. refraction
b. pulse duration
c. spatial pulse length
d. efficiency
e. sensitivity
a. refraction
Which three things determine beam diameter for a disk transducer?
a. pulse duration
b. frequency
c. aperture
d. distance from disk face
e. efficiency
b. frequency, c. aperture, d. distance from disk face
A two-cycle pulse of 5 MHz ultrasound produces separate echoes from reflectors in soft tissue separated by 1 mm. T or F?
True (axial resolution 0.3 mm)
The lower and upper limits of the frequency range useful in diagnostic ultrasound are determined by ______ and _____ requirements, respectively.
a. penetration, attenuation
b. penetration, resolution
c. resolution, penetration
d. attenuation, resolution
c. resolution, penetration
The range of frequencies useful for most applications of diagnostic ultrasound is ______ to _____ MHz.
a. 0.1, 15
b. 2, 20
c. 1, 10
d. 1, 5
b. 2, 20
Because diagnostic ultrasound pulses are usually two or three cycles long, axial resolution is usually equal to _______ to _______ wavelengths.
a. 2, 3
b. 4, 6
c. 1, 3.5
d. 1, 1.5
d. 1, 1.5
