Ultrasound transducers (20%)

Spatial pulse length is equal to: A) the wavelength times the number of cycles in the pulse B) the wavelength minus the number of cycles in the pulse C) the wavelength times the axial resolution D) the wavelength times the beam width E) the wavelength divided by 2

A

What benefit would you obtain by choosing a transducer having a large diameter compared to one having a small diameter? A: It can focus at greater depths B: Increases the frequency C: Increases the beam diameter in the far field D: A and C E: All of the above

A

What best describes the difference between the ultrasound frequencies used for Doppler and for B-mode imaging with a given transducer? A) the frequency for Doppler is usually lower than for imaging B) the frequency for Doppler is usually higher than for imaging C) the transmit pulse for Doppler has a greater bandwidth compared to the bandwidth for imaging D) the frequency for Doppler and for B-mode imaging must be identical for a given transducer E) the frequency for Doppler is usually double that for B-mode imaging

A

What is an advantage of single crystal- or pure-wave crystal transducer? A) wide bandwidth B) lower frequencies at higher resolution C) absence of aliasing with pulsed Doppler D) higher frame rate E) greater steering angles

A

What is the advantage of using multiple transmit focal zones? A) increased lateral resolution B) increased temporal resolution C) increased elevational resolution D) increased axial resolution E) all of the above

A

What is the main advantage of using a 1.5D or multirow array transducer? A) narrow slice thickness over a large part of the scanned volume B) increased penetration C) improved axial resolution D) faster frame rates E) smaller footprint

A

What is the purpose of curving the transducer elements or applying a lens over the elements? A) to provide focusing in the out-of-plane (elevation) direction B) to reduce the acoustic impedance mismatch between the crystal and skin C) to reduce crystal ringing and improve axial resolution D) to help reduce electronic interference E) all of the above

A

What term describes the ability of an imaging device to separate closely spaced objects? A) resolution B) penetration C) duty factor D) interference E) reflection

A

What transducer component is designed to control ringing of the piezoelectric element? A: Backing material B: Electrical insulator C: Matching layer D: Radiofrequency shield E: Lens

A

What transducer component reduces reflection at the transducer/skin interface? A: Matching layer B: Lens C: Element D: Backing material E: Radiofrequency shield

A

Which of following best describes the f-number? A) focal length divided by the aperture B) aperture multiplied by the number of elements in the transducer C) number of transducer elements divided by the Fraunhofer zone D) beam width 1 cm from the transducer surface E) focal length multiplied by the number of elements in the transducer

A

Which type of transducer should you select to produce the narrowest slice thickness throughout the image plane? A) 1.5D multirow array B) a phased array with a small footprint C) a tightly curved curvilinear array D) a mechanical sector E) a mechanically rocked 3D transducer

A

With a 1D linear array, where in the out-of-plane dimension is the dimension of the sound beam the narrowest? A) it is at the point of mechanical focusing B) it is at the point of electronic focusing C) the beam is the same width throughout the image D) it is in the far field E) it is always located at a depth equal to one-half of the transducer aperture

A

You are using a linear array transducer to evaluate the thyroid gland. For standard B-mode imaging, this transducer most likely produces pulses of how many cycles? A: One to three B: Three to six C: Six to nine D: Nine to twelve E: Twelve to fifteen

A

You can reduce beam width to improve spatial resolution in the image by which of the following? A: Focusing B: Decreasing aperture C: Decreasing transducer diameter D: Decreasing transducer width E: Increasing backing material

A

If the frame rate is too slow for adequate temporal resolution, what action could you take to improve frame rate? A: Reduce the number of transmit focal zones B: Increase the scan line density C: Increase the scanning depth D: Decrease the dynamic range E: Reduce the transmit frequency

A a pulse/listen cycle is required for each transmitted focal zone. it follows, then, that as the number of zones are increases, the time required to create one frame is decreased

What type of transducer could you choose to produce a beam that is symmetrical about the beam axis? A) annular array B) linear sequenced array C) phased array D) curved array E) tightly curved array

A annular array is a round transducer in which the elements are arranged concentrically, creating a cone shape beam that is symmetric in all dimension

If the number of cycles in the transmitted puled wave is increased: A) axial resolution is degraded B) lateral resolution is degraded C) spatial pulse length becomes shorter D) rate of attenuation is increased E) penetration is decreased

A axial resolution is proportional to pulse length axial resolution is degraded as pulse length increases pulse length is increased by increasing the number of cycles in the pulse

With a standard one-dimensional linear array transducer, what type of resolution is affected most by electronic focusing and dynamic aperture? A: Lateral resolution B: Contrast resolution C: Temporal resolution D: Axial resolution E: Elevational resolution

A lateral resolution is improved at depth by increasing transducer width or aperture size in an array. essentially, the larger the aperture (the active potion of the array), the smaller the beam width at the focal point

A method used to improve frame rates with multizone electronic focusing is termed: A: Apodization B: Parallel processing C: F-number focusing D: Low-Q transducers E: None of the above

B

If you wish to perform a sonogram with the largest possible field of view in the near field and at depth, what type of array transducer would be preferable? A) linear array B) curved array C) phased array D) sector E) all of the above

B

In order to focus a sound beam relatively far away from the transducer, it is advantageous to: A: Increase the thickness of the element B: Increase the diameter of the element C: Decrease the width of the element D: Decrease the frequency of the element E: Increase the curvature of the element

B

Which represents the best measure of resolution for modern-day ultrasound scanners? A) contrast B) axial C) lateral D) elevational E) temporal

B

Which transducer will exhibit the LEAST amount of volume averaging? A: Mechanical single element B: 1.5D or multi-row array C: Linear array D: Phased array E: Convex array

B

You are reviewing an ultrasound image that has a sector display format that narrows to a point at the transducer surface. What kind of transducer was most likely used to acquire this image? A) linear array B) phased array C) curved array D) annular array E) mechanical sector

B

You are using a 5 MHz, 40 mm linear array transducer to image a structure. What is the width of the image? A) 20 mm B) 40 mm C) 60 mm D) 80 mm E)120 mm

B

You notice a loss in detail in lateral dimension of the ultrasound image. What can you do to improve this? A) decrease the number of focal zones B) increase the scan line density C) decrease the transducer frequency D) increase the frame rate averaging E) increase the dynamic range

B

You suspect that a bright spot on the B-mode image is a calcification, but a posterior acoustic shadow is not present. how can you best optimize your system to demonstrate a shadow distal to the calcification? A) move the focal zone well below the hyperechoic focus B) increase the transducer frequency C) increase the acoustic power D) increase the dynamic range E) decrease the scan line density

B

Increasing the number of transmit focal zones to improve spatial resolution involves the following tradeoff: A) lateral resolution vs. axial resolution B) lateral resolution vs. temporal resolution C) spatial resolution vs. contrast resolution D) contrast resolution vs. frame rate E) elevational resolution vs. frame rate

B Each transmit focus requires a pulse/listen cycle. As more focal zones are added, the frame rate is decreases. Temporal resolution is related to frame rate.

The conversion of an incident pressure wave to an electric signal is the: A) curie effect B) piezoelectric effect C) Doppler effect D) snell effect E) Huygens effect

B a sound wave is a pressure wave. conversion of a sound wave to an electric signal occurs when the sound wave strikes the transducer surface

Which of the following describes a phased array transducer? A) electronically focused in two dimensions and mechanically steered B) electronically focused along the length of the array, mechanically focused along the elevation dimension (width) and electronically steered C) electronically focused along the elevational dimension of the array, mechanically focused along the length of the array and unsteered D) mechanically focused in two dimensions and mechanically steered E) electronically focused along the width of the array, mechanically focused along the length of the array and mechanically steered

B all of the elements are fired as one group but with very small time delays to steer the beam

Which factor LEAST influences axial resolution? A: Damping B: Beam width C: Frequency D: Pulse duration E: Pulse frequency

B beam width affects lateral resolution

Which of the following minimizes the degree to which beam width varies with depth? A) apodization B) dynamic aperture C) coprocessing D) rectification E) frame averaging

B by varying the active aperture with depth, the beam width variation is reduced

What is the disadvantage of using multiple transmit focal zones? A) decreased lateral resolution B) decreased temporal resolution C) decreased elevational resolution D) decreased axial resolution E) all of the above

B each transmit focal position requires a separate pulse-echo sequence. multiple focal zones improve lateral resolution but degrade temporal resolution

When an electric signal is applied to a piezoelectric element, what happens to the element? A) it undergoes temperature fluctuations B) it expands and contracts C) it produces an electric signal of the opposite polarity D) it emits electromagnetic radiation E) it loses its piezoelectric properties

B this expansion and contraction of the element produces the mechanical vibrations we call sound waves

For a single transducer to offer multiple frequency selections for scanning it must have? A) large dynamic range B) wide bandwidth C) multiple rows of elements in the elevation plane D) dynamic aperture E) electronic steering capability

B with a wide bandwidth probe, a range of transmit frequencies is possible. this allows multiple frequencies to be selected with one probe

Axial resolution is determined chiefly by: A) beam width B) transducer diameter C) pulse duration D) line density E) frame rate

C

During the course of a sonographic exam, you notice lateral splaying of the echoes in the far field. What can you do to improve the image? A: Use the maximum acoustic power. B: Use the lowest line density setting. C: Increase the number of transmit focal zones and optimize their location. D: Decrease the scanning depth. E: Increase the sector width.

C

Electronic focusing in the transmit mode is accomplished using: A) curved crystal elements B) changeable lens C) time delays to excite transducer elements D) high pulse repetition elements E) receive time delays

C

What can you do to improve contrast resolution in the ultrasound image? A) increase the sector width B) decrease the number of focal zones C) use a 2D or matrix array transducer D) use a phased array transducer E) use a curved array transducer

C

What defines the best axial resolution that can be obtained with a given transducer? A: Spatial pulse length x 2 B: Spatial pulse length x 4 C: Spatial pulse length / 2 D: Spatial pulse length / 4 E: Equal to the spatial pulse length

C

Where is the point of maximum intensity in a sound beam? A) curie point B) fresnel zone C) focal point D) fraunhofer zone E) f number

C

Which of the following transducer types is best suited to cardiac imaging? A) mechanical sector B) linear array C) phased array D) convex array E) annular array

C

Which statement is most accurate regarding resolution with a standard one-dimensional linear array transducer? A) axial resolution is the worst measure with this type of transducer B) lateral resolution is the worst measure with this type of transducer C) elevational resolution is the worst measure of resolution with this type of transducer D) isotropic spatial resolution is achieved E) temporal resolution is the worst measure of resolution with this type of transducer

C

You are performing an exam on a patient with highly attenuating tissue. Which of the following solutions would be most likely to improve penetration through the tissue? A) decrease dynamic range B) decrease near-field TGC C) choose a lower frequency transducer D) increase the scan line density E)change the gray-scale map

C

You are using a linear array transducer with 4 transmit focal zones. How many pulses are required on each scan line to create the image? A: One B: Two C: Four D: Six E: Eight

C

Which of the following is not associated with a low-Q transducer? A) wide bandwidth B) multifrequency selection C) long pulse length D) diagnostic pulsed-wave ultrasound E) loss of most energy in first few vibrations

C Low-Q transducers have a wide bandwidth, which allows for multifrequency selection. they have a short pulses for good axial resolution

Increasing which of the following will result in improved axial resolution? A) pulse duration B) pulse length C) frequency D) period E) focusing

C axial resolution is improved by reducing pulse length or pulse duration. this can be accomplished by reducing the number of cycles in a pulse (damping) or by reducing the size of the wavelength (increased frequency)

For a nonfocused transducer, the region between the transducer element and the point at which the sound beam is narrowest is called the: A: Far field B: Fraunhofer zone C: Near zone length D: Focal distance E: Both A and B

C near zone length is also called the fresnel zone or near field

What method best describes the method used to create the triangular-shaped image format in the image below A) mechanical steering B) electronic steering with elements fired in small groups C) electronic steering with most elements fired for each pulse-echo sequence and short time differences steering the beam D) curved lens E) mirror

C phased array transducers (sometimes called linear phased array or sector transducers) form the beam by firing most, if not all, elements at once with small time differences

What type of transducer has the same measurement for elevational and lateral resolution A) convex linear array B) phased linear array C) annular array D) sequential linear array E) mechanical sector

C annular array transducer produces a beam that is symmetric about the beam axis. therefor, its lateral resolution is equal to its elevation (slice thickness) resolution

If you choose a lower-frequency transducer to image a highly attenuating structure, what trade off are you making? A: Decreased penetration for increased resolution. B: Decreased beam intensity for longer wavelengths. C: Decreased spatial resolution for improved penetration. D: Increased beam refraction for higher sound speed. E: Increased round-trip travel time for improved resolution.

C higher frequencies have better spatial resolution but greater attenuation than low frequencies. if improved spatial resolution is desired, then one must sacrifice penetration by using a higher frequency

Another name for axial resolution is: A) transverse resolution B) azimuthal resolution C) angular resolution D) range resolution E) A and C

D

Dynamic receive focusing uses? A) mechanical means to focus the beam B) time delays to excite array elements C) variable number of elements to form the transmitted beam D) time delays before echo signals from array elements are combines E) all of the above

D

For a linear array transducer consisting of a single row of elements, what method is most used to focus the beam in the elevational direction? A: Transmit focusing B: Dynamic receive focusing C: Aperture focusing D: Mechanical focusing E: None of the above

D

If you are using a transducer with poor elevation resolution, which of the following problems are you most likely to encounter? A) inability to resolve two structures that lie close together and parallel to the path of the beam B) inability to resolve two structures that lie close together, perpendicular to the path of the beam, and parallel to the long axis of the transducer C) inability to penetrate through dense tissue D) inability to clearly demonstrate small cystic structures E) inability to demonstrate rapidly moving structures accurately

D

Increasing the frequency on a multifrequency transducer from 3.5 MHz to 5.0 MHz will: A) increase the sound propagation speed B) increase the pulse length C) increase penetration D) decrease the pulse repetition frequency E) decrease the wavelength

D

The shape corresponding to the image created by a phased array transducer most closely corresponds to which of the following? A) square B) curved C) trapezoid D) cone

D

What can you do to achieve a higher frame rate? A) decrease the number of focal zones B) decrease the line density C) decrease the sector width D) all of the above E) none of the above

D

What is the main advantage of using an intracavitary probe compared to a standard transducer? A) the intracavitary probe has superior focusing capabilities because of the increases radius of the curved probe face B) the intracavitary probe uses a lower frequency that provides superior penetration and closer inspection of the pelvic structures C) the intracavitary probe does not demonstrate side lobes or grating lobes because of the close spacing and curvature of the elements D) since the intracavitary probe is close to the area of interest, a higher frequency transducer can be used, resulting in superior spatial resolution E) bioeffects are greatly reduces with the intracavity probe because of its frequency range and power output

D

What is the purpose of applying multiple layers to the transducer face? A) the gel gradually erodes the matching layer, and using multiple layers lengths the life of the transducer assembly B) because the impedance of tissue is quite variable from patient to patient, multiple matching layer improve the likelihood of providing a close impedance match to each patient C) each individual coating of the matching layer contributes to the damping of the sound pulse, which results in improved axial resolution D) multiple matching layers result in increased transducer bandwidth E) each coating of the matching layer provides focusing at a specific depth. with multiple layers, multiple points of focus are possible

D

What type of focusing decreases the frame rate? A) mechanical focusing B) dynamic receive focusing C) dynamic aperture focusing D) multiple transmit focusing F) curved crystal focusing

D

You are scanning a phantom containing multiple rows of identical 5 mm spherical fluid-filled structured embedded in a tissue-mimicking material. What type of resolution is best evaluated with this phantom? A) axial B) lateral C) contrast D) elevation E) temporal

D

Imaging frame rate decreases when you: A) decrease frequency B) increase dynamic range C) increase frame averaging D) increase sector width E) decrease the number of transmit focal zones

D by increasing the sector width, the user forces the system to fire more line of sight (scan lines) for each imaging frame. this increases the length of time it takes to create each frame and causes a decrease in frame rate

The sound beam can be focused by all of the following except: A: Acoustic mirror B: Acoustic lens C: Curved crystal D: Matching layer E: Electronic phasing

D matching layer is used to reduce the acoustic impedance mismatch between the crystal and tissue

What is the purpose of the radiofrequency shield that is placed around the crystal and backing material of the ultrasound probe? A) it helps to transmit radio waves into the body B) it aids trasnmission of the electric signal to the crystal C) it reduces the incoming electric signal strength from the body D) it reduces elctromagnetic interference E) it improves axial resolution

D reduces the noise and enhances sensitivity to weak signals

What type of transducer was used to create this image of the uterus? (TV image) A) linear array B) phased array C) single-element mechanical D) tightly curved array E) sector

D tight curvature increases the field of view while keeping the probe size small

What type of resolution is affected most by pulse duration? A) lateral resolution B) contrast resolution C) temporal resolution D) axial resolution E) elevational resolution

D we usually think of axial resolution as being determined by SPL. SPL and pulse duration are directly related. pulse duration is the length of time required to complete one pulse. the shorter the pulse duration, the better the axial resolution

Axial resolution is improved with: A) increased bandwidth B) shorter pulse length C) shorter wavelength D) B and C E) all of the above

E

Spatial resolution consist of: A) contrast and temporal resolution B) temporal and axial resolution C) axial and contrast resolution D) contrast and lateral resolution E) lateral and axial resolution

E

The ability to distinguish between adjacent structures that produce echoes of similar amplitude is termed: A) spatial resolution B) axial resolution C) lateral resolution D) temporal resolution E) contrast resolution

E

The transducer you are using is an array assembly. What is an advantage of this type of transducer? A: Transducer arrays produce pure, single-frequency beams B: Transducer arrays enable mechanical steering C: Transducer arrays produce very long pulses for improved axial resolution D: Transducer arrays have greater dynamic range, resulting in more displayed shades of gray E: Transducer arrays enable electronic focusing and steering

E

The ultrasound system in your lab has a transducer with a small footprint. This kind of transducer has the following disadvantage: A) it cannot be focused in the elevational direction B) the field of view in the far field is only one-quarter the diameter of the transducer C) the near-field lateral resolution is poor D) the Q value is very high E) resolution is degraded at large distances

E

What factor LEAST influences lateral resolution? A: Frequency B: Focus depth C: Beam width D: Transducer diameter E: Damping

E

What type of resolution is most affected by the mechanical focus on a linear array transducer? A) lateral resolution B) contrast resolution C) temporal resolution D) axial resolution E) elevational resolution

E

Which of the following transducers produces side lobes or grating lobes? A) mechanical sector B) linear sequential array C) phased array D) convex array E) all of the above

E

Which of the following will not improve axial resolution? A) increased damping B) increased transducer frequency C) increased bandwidth D) decreased pulse length E) increased focusing

E focusing improves lateral resolution because it decreases beam width

When you increase the scan line density in the B- mode image, you improve: A) temporal resolution B) contrast resolution C) slice thickness D) axial resolution E) lateral resolution

E lateral resolution decreases when the distance between vectors (lines of sight) is greater than the beam width

Which statement is not true regarding lateral resolution? A) it is equal to beam width B) it is improved by focusing C) it is defined as the minimum separation required to resolve two structures perpendicular to the beam axis D) it is also known as azimuthal resolution E) it remains constant throughout scanning depth

E lateral resolution varies with depth. it is best at the focal point and degrades on either side

Which transducer would have a lower line density in the far field compared to the near field? A: Linear array B: Curved array C: Tightly curved array D: Phased array E: B, C, and D

E only linear array transducer has the same line density for both the near and far fields

What array transducer fires all of the elements for each acoustic scan line, using small time delays to steer the beam? A: Linear segmental array B: Convex array C: Annular array D: Linear sequential array E: Phased array

E phases array fires all of its elements to create each acoustic scan line. small time delays are employed to focus the beam and beam steering

Which of the following can not be evaluated with a tissue-equivalent phantom? A) axial resolution B) lateral resolution C) contrast resolution D) slice thickness E) temporal resolution

E temporal resolution is related to the time it takes to complete a single frame of information. this cannot be assessed with a tissue phantom which there are no moving parts

What is the main advantage the standoff pad provides to improve the image? A) acoustic impedance closer to that of a crystal, which results in improved transmission of sound into the body B) has a propagation speed equal to twice that of soft tissue, which decreases the wavelength of the sound beam C) increases the distance between the transducer and the mass, making it more likely that the mass will be located close to the elevational focus of the sound beam D) creates a soft interface between the crystal and the tissue, increasing constructive interference and reducing scattering E) eliminates artifacts associated with reverberation, side lobes, and grating lobes

c