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Ultrasound Physiscs > SPI Practice Exam 3 > Flashcards

SPI Practice Exam 3 Flashcards

1
Q

*If each image required 50 acoustic pulses and your system displays 30 images per second, what is the PRP?

  • 0.67 micro second
  • 1500 Hz
  • 1500 ms
  • 0.67 ms
A

0.67 ms

*PRF = #s of pulse produced per second

In this case, PRF = 50 pulses per image x 3- images per second = 1500 Hz

*PRP = reciprocal of PRF = 1/1500 Hz = 0.00067s or 0.67 ms

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2
Q

Assuming line density is constant at 2 lines per degree and you change from a 45 degree sector to a 90 degree sector, how many scan lines will be now be produced?

  • 45
  • 90
  • 180
  • 360
A

180

With constant line density, if the degree of the sector angle doubles, the number of pulses produced will double. This will decrease the PRF and the frame rate

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3
Q

*Constructive and destructive interference are demonstrated on the image as what acoustic artifact?

  • speckle
  • reverberation
  • posterior shadowing
  • posterior enhancement
A

speckle

*When constructive and destructive interference can occur as the reflected waves return to the transducer. The interference can reinforce or diminish the reflections. The varied levels of interference cause a grainy pattern referred to as speckle. It reduces the signal to noise ration and degrades the image.

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4
Q

*Which of the pulses produced from a 7MHz transducer would have the best lateral and axial resolution?

  1. 8mm beam diameter, 8 pulses per cycle
  2. 2 mm beam diameter, 3 pulses per cycle
  3. 2 mm beam diameter, 8 pulses per cycle
  4. 8 mm beam diameter, 2 pulses per cycle
A

2

The more narrow the beam, the better the lateral resolution.

Axial resolution is best with shorter pulse lengths

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5
Q

When using virtual beam forming the US beam is describes as:

  • high volume
  • laser-thin
  • rectangular
  • cylindrical
A

laser-thin

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6
Q

If the media 1 has an impedance of 65 rayls and media 2 also has an impedance of 65 rayls, what percentage of the beam will be transmitted at their interface?

  • 100%
  • 50%
  • 0%
  • unable to determine with information given
A

100%

Read question! asking about transmission, not reflection

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7
Q

Which of the following describes the best way to eliminate the color Doppler aliasing in the proximal hepatic veins while maintaining proper flow display in the distal hepatic veins?

  1. invert the color baseline
  2. increase the color velocity scale to 0.40 m/s
  3. decrease the color priority
  4. increase the color velocity scale to 0.60 m/s
A

2

venous flow is normally low velocity. a small increase in color velocity scale will have a large effect on the display of venous flow.

increasing the scale should eliminate the aliasing and also help to maintain the normal display of the slower flow in the distal vessel.

*increasing to 0.60m/s would reduce the color flow across the image because the average flow velocity of venous flow is much less than 0.60 m/s

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8
Q

Which of the following imaging technique relies on Young’s modulus for the cloror displayed? Use your mouse to position the cursor over the image that demonstrates the answer and click to select it.

A

c

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9
Q

Which image demonstrates refractive shadowing?

A

D

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10
Q

Which if the following is correct regarding endocavity probes?

  1. They should be cleaned and soaked in a high level disinfectant at least once a day
  2. One of the main disadvantages of the tightly curved elements of the endocavity probe is degraded spatial resolution
  3. They most commonly incorporate a curved array of elements that are electronically steered to create an extended field of view
  4. endocavity probes offer improved lateral resolution at greater depths
A

3

Endocavity probes most commonly use tightly curved element arrays

One of the main advantages of the tightly curved elements of the endocavity probe is improve spatial resolution

endocavity probes are limited by degraded lateral resolution at greater depth

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11
Q

*What part of the US system is responsible for changing the PRF with changes in image depth?

  • analog to digital scan converter
  • FFT
  • digital to analog converter
  • pulser
A

pulser

The pulser adjusts the timing of the voltage applied to the crystals to adjust the PRF

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12
Q

*What should be done to adjust and improve the color Doppler displayed on the image?

  • increase PRF
  • increase velocity scale
  • decrease sample volume
  • steer box
A

decrease the sample volume

Color Doppler processing ability improves as the size of the area evaluated is decreased.

The smaller sample size allows faster frame rates and blood flow display. Increasing color velocity and PRF would decrease the amount of color currently

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13
Q

*______ occurs posterior to highly attenuating structure

  • shadowing
  • enhancement
  • refraction
  • misregistration
A

shadowing

a highly attenuating structure - inhibits the transmission of sound which produces an anechoic area posterior to the structure = shadowing

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14
Q

*If you are performing an abdominal exam, but inadvertently (accidentally) select the carotid preset on the machine, how will this affect your exam?

  1. Depth settings will be very superficial causing potential non-invisualization of the abdominal structure
  2. Aliasing of all arterial waveforms will occur
  3. the phased probe will be activated instead of the linear probe
  4. Color will not be displayed in the abdominal vessels due to high PRF settings
A

1

Carotid preset will be set to a very low imaging depth due to the superficial course of the carotid arteries.

The preset for abdominal is set to begin at a much higher depth setting

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15
Q

Which of the following system control adjustments will increase the amount of color Doppler that is superimposed over the 2D image?

  1. increased threshold and increased persistence
  2. increased wall filter and increased threshold
  3. decreased threshold and persistence
  4. decreased persistence and increased wall filter
A

1

*Threshold control = color priority; sets the limits for where color will be displayed over the 2D image

*Persistence - increase the amount of time a color pixel is displayed over an area

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16
Q

*the unit used for the attenuation coefficient is:

  • dB
  • mW/cm2
  • dB/cm
  • dB/cm/MHz
A

dB/cm

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17
Q

Which type of phantom is necessary to evaluate temporal resolution?

  • fluid filled Doppler phantom
  • AIUM test object
  • tissue phantom
  • hydrophone
A

fluid filled Doppler phantom

*temporal resolution cannot be evaluated with a tissue phantom or AIUM test object because it required moving structure

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18
Q

*US contrast media is least likely to be used in which of the following exam?

  1. echo for suspected septal defect
  2. echo for suspected CAD
  3. evaluation of liver tumor vascularity
  4. evaluation of gallbladder function
A

4

US contrast media is most commonly used to assess the cardiac chambers for abnormal wall motion and septal defect.

In early 2016, the FDA approved the first type of contrast media (Lumason) for evaluation of liver tumor vascularity

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19
Q

*the gray scale map is adjusted to a new map just prior to freezing the image. This is example of?

  1. applying postprocessing
  2. applying preprocessing
  3. adjusting dynamic range
  4. adjusting rejection
A

2

*Preprocessing is performed as the image is “live” or in real time, before it has been stored to memory.

*Postprocessing is performed once the image is frozen and stored in the system memory

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20
Q

Which f the following statement is true regarding the sonographer assisting the radiologist with a biopsy procedure?

  1. the sonographer’s hands must be covered by sterile gloves when removing the biopsy device from the tray to hand to the physicians to start the procedure
  2. the sonographer should wear sterile gloves when disposing of the needles and devices used for the biopsy
  3. the sonographer’s hands must be sterile when opening needles and biopsy device packaging
  4. the sonographer is responsible for creating the point of entry on the patient for the biopsy device
A

1

*anytime you touch a sterile item, your hand must also be sterile. the physician is responsible for creating the point of entry for the biopsy.

If you are only opening the packaging of the sterile items, your hands do not need to be sterile.

After the procedure, sonographers can wear non-sterile gloves to clean up the used items after biopsy

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21
Q

*Which of the following is a function of the signal processor?

  1. amplification and compensation
  2. steering and focusing
  3. apodization and aperture
  4. filtering and compression
A

4

*signal processor performs filtering, detection (demodulation), and compression.

the other functions listed are performed by the beam former.

Steering , focusing, beam scanning and aperture are all performed by the beam former

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22
Q

*Which of the following describes a Multi-dimensonal array?

  1. offers increased slice thickness and improved spatial resolution
  2. has less than 100 elements that can be fired sequentially
  3. has less than 100 elements that can be fired simultaneously
  4. has thousands of elements arranged in a matrix pattern
A

4

*multi-dimensional array TDR has thousands of elements arranged in a matrix pattern.

The element improves elevational resolution by reducing the slice thickness. They are used to produce 3D/4D images

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23
Q

If a pulse has a time of flight of 130 microseconds, what is the depth of the reflector?

A

10cm

For every 13 microseconds of time of a flight of a pulse, the reflector is 1cm deeper in the tissue.

If the time of flight for the pulses is 130 microseconds, the reflector is 10cm deep

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24
Q

*Increasing the TDR frequency on a multihertz TDR will:

  1. improve the axial resolution in the near filed and far field
  2. improve the axial resolution only in the near field
  3. increase the spatial pulse length
  4. improve the lateral resolution in the near field
A

1

higher frequency TDR have a narrow beam width in the far field than lower frequency TDR.

lower frequencies exhibit more beam divergence in the far field than higher frequencies.

*read question! talking about axial resolution. compare higher frequency TDR with lower frequency TDR

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25
Q

What type of precautions is required for a patient with MRSA?

  1. contact precautions
  2. droplet precautions
  3. enteric precautions
  4. protective environment precautions
A

contact precautions

*Wound-skin contact precautions; used t protect others from germs in patient’s wounds or any other heavily contaminated areas; require gown and gloves for any type of patient contact; MRSA, VRE, Scabies, Impetigo

*note: enteric precautions - prevent infections that are transmitted primarily by direct or indirect contact with fecal material

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26
Q

*What effect will a mechanical index of 1.0 have on a contrast echo exam?

  1. An MI setting 1.0 or greater is preferred for contrast exams
  2. the increased beam intensity will burst the contrast bubbles quickly
  3. mechanical index has no effect on contrast exams. the thermal index must be properly set for an optimal contrast exam
  4. the decreased beam intensity will reduce the appearance of the bubbles on the image
A

2

*Normal MI setting should be 0.4 - 0.6 for a_n optimal contrast exam._

The higher MI setting, the greater the risk of bursting the microbubbles and reducing the appearance of the contrast material

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27
Q

Propagation speed error will cause improper positioning of echoes ______ on the image.

  • deeper
  • more superficially
  • laterally
  • medially
A

deeper

*Propagation speed error will cause improper axial positioning of echoes (deeper on the image)

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28
Q

Which of the following TDRs will provide the deepest natural focus?

  1. high frequency, large diameter
  2. high frequency, small diameter
  3. low frequency, small diameter
  4. low frequency, large diameter
A

1

*high frequency, wide diameter TDRs will have the deepest natural focus

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29
Q

If the time to produce each frame is 0.05 second, what is the frame rate?

  • 100kHz
  • 20Hz
  • 10kHz
  • 50Hz
A

20Hz

*time to produce a frame x frame rate = 1

0.05 x FR = 1

FR = 1/0.05 = 20Hz

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30
Q

If the dynamic range is 64dB and there are 32 shades of grey, what is the contrast resolution?

  • 2 dB
  • 0.5 shade/dB
  • 2 dB/shade
  • 0.5 dB
A

2dB/shade

*contrast resolution is defined asa decibels per shade.

Contrast resolution = dynamic range/number of shades

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31
Q

The hydrophone can be used to evaluate all of the following except:

  1. PRP
  2. PD
  3. pulse amplitude
  4. dead zone depth
A

4

The hydrophone is used to evaluate the beam profile using an oscilloscope display.

pulse amplitude, PD, PRP and the period of the wave can be evaluated with this technique.

32
Q

Range resolution of a pulsed wave system is determined by:

  1. the medium only
  2. the frequency and intensity of the beam
  3. the sound source only
  4. both source and medium
A

4

*range resolution is the ability to determine the depth of reflectors. It is determined by the source of the sound and the medium in which it travels

33
Q

*All of the following are coupling agents or medium typically used for US exams, except:

  • ultrasonic gel
  • KY jelly
  • water
  • gastrografin
A

gastrografin

*Gel and KY jelly can be used in most ultrasound exams. some exams use water as a “window” to evaluate adjacent structure (have the patient drink water) such as prostate.

Gastrografin is a contrast material normally used on radiography procedure

34
Q

The ultrasound image is usually created using all of the reflected frequencies in a pulse. when using _______ the reflected frequencies are divided into smaller sections and each of the sections is used to create an image.

  1. frequency compounding
  2. compound imaging
  3. temporal compounding
  4. spatial compounding
A

frequency compounding

The US image is usually created using all of the reflected frequencies in a pulse.

When using frequency compounding, the reflected frequencies are divided into smaller section and each of the section is used to create an image.

35
Q

Which of the following is an advantage of harmonic imaging?

  1. increased beam penetration
  2. increased lobe artifact
  3. increased beam width
  4. increased signal to noise ratio
A

4

Harmonic imaging refers to processing the returning waves at double the frequency and will not increase beam penetration.

the advantage include increased signal to noise ratio and reduced reverberation and lobe artifacts.

36
Q

How do you correct beam width artifact on a Doppler tracing?

  1. decrease the sweep speed
  2. decrease the PRF
  3. increase the incident angle of the Doppler cursor
  4. use a smaller sample size
A

4

*Beam width artifact on a Doppler tracing occurs when you detect two separate flow patterns on the same tracing, such as the aortic outflow and mitral inflow.

Smaller sample sizes allow you to evaluate the flow patterns separately

37
Q

Spatial compounding:

  1. produces a reflection at double the transmitted intensity
  2. can decrease the appearance of useful artifacts such as enhancement and shadowing
  3. relies on the non-linear behavior of sound waves
  4. decreases the signal to noise ratio on the image
A

2

*spatial compounding AKA SonoCT, can be used to reduce image noise and clutter while reducing unwanted acoustic artifacts on the image.

Beam steering is used to acquire several overlapping scans of a structure.

The sans are averages together to reduce speckle, clutter and other imaging artifacts.

spatial compounding can decrease the appearance of useful artifacts such as enhancement and shadowing

38
Q

*All of the following correctly describe a normal Doppler waveform of an artery from the lower extremity, except?

  1. the triphasic waveform has two components of normal retrograde flow during the cardiac cycle
  2. the triphasic waveform has a normal retrograde flow component during the cardiac cycle
  3. the triphasic waveform has two components of antegrade flow during the cardiac cycle
  4. there will be a high resistance peaked waveform with a small amount of flow reversal
A

1

*The resistance in the peripheral vascular beds is very high compared to the abdominal organs.

blood flows into the extremities during systole with flow reversal during diastole. the resistance in vascular beds is greater than the resistance in the feeding vessels during mid/end diastole causing flow reversal to occur in the vessel.

This produces a waveform with 2 separate phases of flow (biphasic) if the pressure gradient between the vascular bed and the feeding vessel continues to equalize, a small amount of flow may move toward the vascular bed at the very end of diastole.

This produces a waveform with 3 separate phases of flow (triphasic). Biphasic and triphasic flow is generally considered normal in the extremities

39
Q

Which of the following TDRs uses a beam former?

  1. sector phased array
  2. sequential curved linear array
  3. mechanical TDR
  4. sequential linear array
A

sector phased array

  • the beam former adjust the timing of the pulses to focus and steer the US beam in phased array TDR
40
Q

As the element diameter decreases, the focal length _______

  1. will decrease
  2. will remain unchanged unless the frequency also changes
  3. will remain unchanged unless the element thickness also changes
  4. will increase
A

will decrease

*element diameter and frequency are directly related to the focal length of a TDR. change in either element characteristic will result in focal depth changes. the smaller the diameter of the TDR, the shorter the focal length. the lower the frequency , the shorter the focal depth

41
Q

*You are using a single element probe with a diameter of 12 mm and focal depth of 6 cm. what is the diameter of the beam at the focal depth?

  • 3cm
  • 2mm
  • 6cm
  • 6mm
A

6mm

*the beam width at the focal depth is equal to ½ the crystal diameter

42
Q

Which of the following causes range ambiguity artifact?

  1. refraction
  2. high PRF
  3. element damage
  4. electrical interference
A

high PRF

*range ambiguity is associated with shallow depth settings.

decreasing the PRF and increasing imaging depth can reduce this artifact.

43
Q

What system component is responsible for 3D image acquisition and presentation?

  1. TDR
  2. signal processor
  3. image processor
  4. beam former
A

image processor

*the image processor is responsible for preprocessing, postprocessing, storing images/cine loops, gray scale maps, _color map_s, 3D image acquisition and presentation, and digital to analog conversion of the signal

44
Q

*which of the following imaging techniques does not require knowledge of the Doppler angle to display flow information?

A

D

power Doppler does not require the angle correction

detect only amplitude

45
Q

what part of the beam former creates the digital to echo signal that is sent to the signal processor?

  1. pulser
  2. amplifier
  3. digital to analog converter
  4. analog to digital converter
A

4

46
Q

Which system component improves lateral resolution?

  1. pulser
  2. thicker PE element
  3. backing material
  4. matching layer
A

1

through timing of the voltage applied to the elements, the pulser electronically focuses the beam to improve lateral resolution

thinner elements produce higher frequencies with improved spatial resolution

47
Q

*Some US TDR arrays allow you to the reduce thickness of the beam as an additional type of focusing. what effect will his change have on the image?

  1. improved elevational resolution
  2. decreased beam attenuation
  3. improved contrast resolution
  4. decreased temporal resolution
A

1

*focusing that occurs along the thickness of the beam will decrease the slice thickness and improve elevational resolution

48
Q

*As the TDR frequency increases, the quality factor _____

  • decreases
  • increases
  • does not change
  • changes only is a different PE element is used
A

increases

*imaging probe have a low Q factor and a wide bandwidth of frequencies

CW and therapeutic US probes have high Q factor and narrow bandwidth due to the continuous production of the wave at the main frequency.

the probe frequency is directly related to the Q factor and indirectly related to bandwidth. the higher the frequency, the higher the Q factor and narrower the bandwidth

49
Q

*Which if the following terms can be used to describe the waveform displayed?

  1. low resistance
  2. phasic
  3. tardus parvus
  4. biphasic
A

low resistance

*low resistance flow demonstrates increased diastolic flow with a slower acceleration to peak and deceleration to end diastolic flow.

No flow reversal occurs in diastole. antegrade flow is present throughout the cardiac cycle

50
Q

*increasing ______ will improve detail resolution the most on the lateral sides of the image.

  • beam width
  • overall gain
  • image depth
  • line density
A

line density

*increasing line density will improve detail resolution the most on the lateral sides of the image. By using more scan lines, the image is created from more reflected information that allows for improved detail

51
Q

*Dynamic focusing refers to:

  1. using the time of flight of pulses to improve resolution
  2. the type of focusing used in a mechanical array
  3. a combination of electronic and mechanical focusing
  4. a combination of frequency compounding and receive focusing
A

1

*dynamic focusing refers to using the time of flight of pulses to improve resolution. It uses a combination of transmit and receive focusing

52
Q

***According to the attached color map, what color will be demonstrated for blood that is moving toward the probe at an average velocity of 100cm/s?

  • yellow
  • red
  • white/light blue
  • blue
A

white/light blue

*flow moving toward the TDR would normally demonstrate red, but when the velocity of the flow exceeds the scale. aliasing occurs.

The white or light blue color of the blue color bar will be seen and is related to the “wrap around” of the color display.

If the flow was moving at 100 cm/s in a direction away from the TDR, the color display would be red/orange because of aliasing. the best wat to fix aliasing on color Doppler is to increase the PRF or velocity scale

53
Q

*Which of the following system controls is used mainly in cardiac imaging to correct for dropout on the sides of the image?

  • 2D priority
  • 3D image rendering
  • lateral gain
  • post-processing
A

lateral gain

*lateral gain: the image is divided into multiple “vertical” zones that are parallel to the axis of the beam.

Potentiometers are assigned to adjust amplification in each vertical zone.

It is commonly used in cardiac imaging to correct for dropout on the lateral aspect of the image to better visualize wall motion and chamber size

54
Q

*Which of the following correctly describes a limitation of the fast Fourier transformer?

  1. cannot process more than two samples per cycle
  2. cannot correctly process a frequency shift that is less than half the TDR frequency
  3. required a minimum of two samples per cycle to process and produce a Doppler tracing
  4. cannot correctly process a frequency shift that is less than one half of the PRF
A

3

*FFT requires a minimum of two samples per cycle to process and produce a Doppler tracing.

most systems obtain 100-400 Doppler samples per scan line. it also cannot correctly process frequency shift that is greater than one half of the PRF and aliasing occurs.

55
Q

*Which of the following will increase the risk of aliasing?

  1. decreasing the image depth
  2. intercept angle of 90 degrees
  3. increase transmit frequency
  4. low velocity blood flow
A

increase transmit frequency

*increasing the transmitted frequency will increase the risk of aliasing on PW Doppler.

Aliasing occurs when the Doppler shift exceeds ½ PRF of the system.

lower Doppler shifts produce lower velocities which would have a lower risk of aliasing.

If the Doppler intercept angle is a 90 degrees, on flow will be displayed.

reducing the imaging depth, will produce a higher PRF and a higher Nyquist limit which will reduce risk of aliasing

56
Q

*What console control should be adjusted to improve the quality of the Doppler tracing?

  1. reduce the wall filter setting
  2. raise the baseline
  3. increase the PW Doppler scale
  4. adjust the placement of the Doppler cursor so it is more parallel to the blood flow
A

4

The image can be improved in multiple ways.

the Doppler cursor is nearly perpendicular to the flow in the vein. By moving the Doppler cursor to the portion of the vessel on the left side of the image, the flow would be more parallel to the sound beam.

The highest quality and most accurate Doppler tracing will be produced when the Doppler cursor is parallel to the flow.

The PW scale could be reduced to help the waveform fill the Doppler area and improve the display of the low flow velocity.

57
Q

***note: attenuation coefficient for soft tissue is ½ frequency

A

A: 2.5dB

½f = 1.25dB

1.25dB x 2cm = 2.5 dB

58
Q

***What is the period for a 5MHz TDR?

A

0.2 microseconds

period = ½f

1/5000000Hz = 0.2 microseconds

59
Q

!!! Which system component improves lateral resolution?

A

pulser

*through the timing of the voltage applied to the elements, the pulser electronically focuses the beam to improve lateral resolution

60
Q

!!!

A
61
Q

!!!

A

distance to reflector = ½ (time to and from) x propagation speed

62
Q

***If the time to produce each frame rate is 0.05 second, what is the frame rate?

A

20Hz

*time to produce a frame x frame rate = 1

0.05 x FR = 1.0

FR = 1/0.05 = 20Hz

63
Q
A

a highly attenuating structure inhibits the transmission of sound which produces an anechoic area posterior to the structure = shadowing

64
Q

!!!Which system component is responsible for 3D image acquisition and presentation?

A

image processor is responsible for preprocessing, post processing, storing images/cine loops, gray scale maps, color maps, 3D image acquisition and presentation, and digital to analog conversion of the signal

65
Q

!!! All of the following are flow characteristics demonstrated with a Doppler tracing, except:

  1. phasicity
  2. intensity
  3. velocity
  4. pulsatility
A

intensity

66
Q

!!! For an US system to produce a real time flicker free image the minimum frame rate required is..

  • 10Hz
  • 60Hz
  • 15Hz
  • 30Hz
A

15Hz

*the frame rate for real time systems varied from 15Hz to 60 Hz. A minimum of 15Hz is required to produce a flicker free image for the human eyes

67
Q

@!!!

A

anterior-posterior

68
Q

***

A

frequency compounding

69
Q

!!!

A

spatial compounding

70
Q

!!! Which of the following causes range ambiguity?

  • element damage
  • refraction
  • high PRF
  • electrical interference
A

high PRF

71
Q

*** As the TDR frequency increases, the Q factor _____

A

Increases

*the higher the frequency, the higher the Q factor

72
Q

!!!

A

accurate but it takes longer to process

73
Q
A

accurate but it takes longer to process

74
Q

!!!

A
75
Q

!!!

A
76
Q

!!!

A

Ultrasound Physiscs (18 decks)

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