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ultrasound > ultra sound first set of questions made by class > Flashcards

ultra sound first set of questions made by class Flashcards

1
Q

Why do we use phased array?

a) To minimise heat
b) To steer the beam of sound
c) To change AC – DC
d) To reduce artifacts

A

b) To steer the beam of sound

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2
Q

How do you control the shape of the beam being produced?

A

Change the focus of the beam

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3
Q

What does TCG stand for?

A

Time gain compensation

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4
Q

What does A stand for?

A

Amplitude

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5
Q

What does focus control?

a) Penetration depth
b) Region of best resolution
c) Enlarges ROI
d) Pulse repetition frequency

A

b) Region of best resolution

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6
Q

When does refraction occur?

A

Deviation is in the path of a beam, it occurs when the beam passes through interfaces between tissues of differing speeds of sound, when the angle of incidence to an interface is not 90o

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7
Q

As the pulse travels through the body it loses energy due to what?

A

Backing material

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8
Q

What are the 6 steps for processing?

A
  1. Detection
  2. Preamplification
  3. Time gain compensation
  4. compression
  5. rectification and envelope detection
  6. rejection
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9
Q

What will too much preamplification produce?

A

introduce excessive noise into the subsequent analysis

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10
Q

The machine is calibrated so that the speed of sound is what?

A

1540 m/s which is the speed of sound in soft tissue

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11
Q

What does the speed in which the pulse travels through the body depend on?

A

The tissue type e.g. fat muscle blood and bone

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12
Q

If rejection threshold is too low what happens?

A

leads to many echoes which don’t represent anatomy

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13
Q

We look at data through a what?

A

window

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14
Q

Name 2 advantages of A mode:

A

Very quick as only 1 pulse needs to be sent out

Can give a clear picture on the anatomical boundaries

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15
Q

Name 2 disadvantages of A mode:

A

Small amount of data means less to interpret

Only 1 dimensional

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16
Q

What takes longer to produce A or M mode?

A

M Mode

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17
Q

What type of pulse will produce a wide range of frequency’s?

A

Narrower pulses

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18
Q

Define the term axial resolution:

A

The ability to display small targets along the path of the beam as separate entities

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19
Q

Define pulse length and wave length:

A
  • Pulse length is determined by number of cycles in one pulse and length of each cycle (ie: wavelength)
  • inversely proportional to frequency (c=fλ) so higher frequencies generate shorter wavelengths and therefore shorter pulse lengths
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20
Q

What is a backing material made from?

A

epoxy resin with rubber powder embedded in the epoxy

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21
Q

What is a phased array used for?

a) Increase frequency
b) Steer the bandwidth
c) Decrease the signal
d) Steer the sound beam

A

d) Steer the sound beam

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22
Q

What is a transducer and what is its purpose?

A

transducer in an ultrasound instrument

changes electrical energy into sound energy, and it can change sound energy into electrical energy.

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23
Q

What do piezoelectric crystals respond to?

A

to an electric field by producing pressure

24
Q

basic transducer consists of 3 main parts

A
  1. The case
  2. The crystal
  3. The damping material – more on that soon
25
Q

The input to a transducer is called what?

A

Signal

26
Q

Electrical signal coming in to the transducer produces?

a) Sound at a different frequency
b) Stays at an electrical signal
c) Sound at the same frequency
d) Returning echos

A

d) Returning echos

27
Q

Explain the superposition principal:

A

When more than one wave is present at a given point we can simply add the value of the waves together at that point

28
Q

Why is coupling gel needed in USS examinations?

a) Decrease noise
b) Remove impedance difference
c) Lubrication to reduce friction
d) Increase impedance difference

A

b) Remove impedance difference

29
Q

What is the chosen wavelength difference for the matching layer?

A

¼ wavelength

30
Q

The longer the pulse the ……………… the bandwidth.

A

Narrower

31
Q

The ALARA principle is still relevant is USS:

a) True
b) False

A

a) True

32
Q

What is not a type of interaction in USS?

a) Thermal
b) Mechanical
c) Photoelectric

A

c) Photoelectric

33
Q

Give settings that will affect heating:

A
  1. Output power
  2. Frequency
  3. Duration
  4. Mode (scanned or unscanned)
  5. Focal zone position
  6. Field of view
34
Q

Which one isn’t a form of recording method?

a) Static imager
b) Reverberation
c) Cine loop
d) Pacs storage

A

b) Reverberation

35
Q

Give USS assumptions:

A
  1. Sound travels in strait lines
  2. Echos originate only from objects along the beams axis
  3. The intensity of the echos relates directly to the reflecting or scattering properties of distant objects
  4. Sound travels at a fixed speed in the body
  5. The attenuation is the same for all tissues being imaged
  6. Tissue that should look the same does look the same
36
Q

The USS machine assumes sound travels at what speed?

A

1540 m/s-1

37
Q

What is one of the main biological effects of USS?

a) Nausea
b) Heating
c) Radiation dose
d) None of the above

A

b) Heating

38
Q

Gives examples of in vivo biological effects:

A
  1. Foetal weight loss
  2. Foetal death
  3. Blood flow anomalies
  4. Lung haemorrhage
39
Q

Give examples of in vitro biological effects:

A

1) Mitosis rates altered
2) Cell membranes ruptured
3) Change in cell motility
4) Cell death
5) Degradation

40
Q

How does edge shadowing appear?

a) A line that appears brighter
b) A darker line is shown tangential to edge
c) 3 or more lines shown perpendicular to each other
d) A brightened area

A

b) A darker line is shown tangential to edge

41
Q

Depth artefacts include:

a) Reverberation
b) Side lobes
c) Side width
d) Comet tail
e) A & D

A

e) A & D

42
Q

Describe the appearance of comet tail artefact:

A

Loss of energy with reverberation cycle which results in a rapid brightness of the artefact.

43
Q

When does refraction occur?

a) Where the echoes are presumed to have come from along the original beam path and are therefore place in an incorrect position on the ultrasound image.
b) When the lobe are circumferential around the main lobe
c) Where there is misregisistration by half the band width
d) When there is a short range of reverberation effect

A

a) Where the echoes are presumed to have come from along the original beam path and are therefore

44
Q

What is an artefact?

A

An appearance in an ultrasound image that does not accurately represent the anatomy or structure of the section in the path of the beam.

45
Q

What is not a cause of artefact?

a) Violation of assumtions (acoustic artefact)
b) Faulty equipment
c) Electrical interference
d) Bandwidth

A

d) Bandwidth

46
Q

Define shadowing:

A

Caused by a high degree of attenuation of the beam at an interface.

47
Q

How does shadowing appear?

A

Darkened line cast behind a region of greater attenuation than surrounding tissue.

48
Q

Enhancement is?

a) Brightened line behind a region of low attenuation than surrounding tissue.
b) Darkened line behind a region of high attenuation than surrounding tissue.

A

a) Brightened line behind a region of low attenuation than surrounding tissue.

49
Q

How does edge shadowing appear?

a) A line that appears brighter
b) A darker line is shown tangential to the edge
c) 3 or more lines shown perpendicular to eachother
d) A brightened area

A

b) A darker line is shown tangential to the edge

50
Q

What does colour Doppler flow indicate?

A

Flow direction and speed

51
Q

What are the four ways blood can flow in a vessle?

A

1) Plug flow
2) Lamina flow
3) Disturbed flow
4) Turbulent flow

52
Q

What are the 5 stages the system goes through when receiving Doppler information?

A

1) Amplification
2) Compensation
3) Compression
4) Demodulation
5) Rejection

53
Q

What is used in pulse wave Doppler to select a window in time during which echoes are allowed to pass to the receiver?

1) Window
2) Gate
3) Tunnel
4) Channel

A

1) Window

54
Q

The shorter the pulse the better the ……………. Resolution

a) Longitudinal
b) Lateral
c) Transverse
d) Axial

A

a) Longitudinal

55
Q

What is aliasing?

A

The rate at which we sample the signal can cause the sonographer to miscalculate the rate of motion in the body.

56
Q

What is half the Doppler PRF?

A

Nyquist limit

ultrasound (1 decks)

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