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DMS 101- Ultrasound Physics > Test 3- Assignments and powerpoints > Flashcards

Test 3- Assignments and powerpoints Flashcards

Arrays 1 and 2 assingments. both powerpoints

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1
Q

T/F

Side lobes are created by array transducers.

A

False

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2
Q

T/F

The PRF (pulse repetition frequency) is determined/controlled by the number of lines per frame and the frame rate?

A

True

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3
Q

A sonographer who is using a phased array scanner changes from 4 focal zones to one. What is the most likely consequence of this action?

A)frame rate decreases
B)temporal resolution degrades
C) imaging depth increases
D) temporal resolution improves

A

D) temporal resolution improves

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4
Q

Which of the following forms of resolution improves when frame rate increases?

A) lateral resolution
B) longitudinal resolution
C) temporal resolution
D) spatial resolution

A

C) temporal resolution

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5
Q

The near zone length of a transducer depends on

A) propagation speed and frequency
B) frequency and transducer diameter
C) field of view and transducer diameter
D) path length and frequency

A

B) frequency and transducer diameter

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6
Q

Grating lobes in electronic array systems

A) increase with increased steering angle
B) decrease with increased steering angle
C) are eliminated at high frame rates
D) are not likley to produce artifacts

A

A) increase with increased steering angle

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7
Q

The frame rate of a real-time scanner that uses an electronic array depends on:

A) velocity of sound
B) the image depth
C) number of lines in the image
D) all of the above

A

D) all of the above

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8
Q

Which of the following has a fixed focus and uses two crystals; one for transmitting and one for receiving?

A) A-Mode
B) M-mode
C) continuous wave mode
D) pulse-echo mode

A

C) continuous wave mode

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9
Q

Of the choices below, which transducer would be well suited to intercostal scanning?

A) linear sequenced array, real-time
B) mechanical sector, real-time
C) static scanner with large diameter

A

mechanical sector, real-time

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10
Q

Which of the following transducers would be most useful for penetration of an obese patient?

A) 5 MHz, short focus
B) 3 MHz, long focus
C) 5 Mz, long focus
D) 2.5 MHz , short focus

A

B) 3 MHz, long focus

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11
Q

Beam thickness artifacts primarily depend on

A) position of the patient
B) gas bubbles
C) beam angulation
D) gravity

A

C) beam angulation

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12
Q

Which of the following varies with distance from the transducer?

A) SPL
B) axial resolution
C) frequency
D) lateral resolution
E) none of the above

A

D) lateral resolution

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13
Q

A longer near zone can be obtained by _______.

A) using a higher frequency transducer
B) using a lower frequency transducer
C) decreasing the diameter of the transducer
D) increasing damping

A

A) using a higher frequency transducer

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14
Q

T/F

Real time imaging is only possible with electronic arrays

A

False

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15
Q

T/F

It is not possible to steer an annular phased array electronically

A

True

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16
Q

T/F

The number of scan lines within a given area is called the line density

A

True

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17
Q

T/F

Linear phased array scanners need no form of mechanical focusing in the elevational plane because focusing is performed electronically

A

False

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18
Q

T/F

The beam diameter is constant in the near zone

A

False

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19
Q

T/F

An annular array scanner uses mechanical beam steering

A

True

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20
Q

T/F

A linear sequenced array can never be dynamically focused

A

False

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21
Q

Lateral Resolution

A) and ring-down are the same
B) depends on the beam diameter
C) determines penetration depth
D) cannot be measured in the far zone

A

B) depends on the beam diameter

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22
Q

T/F

The beam diameter is constant in the far zone

A

False

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23
Q

T/F

An annular array scanner uses mechanical beam steering

A

True

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24
Q

T/F

Line density is determined by the number of scan lines within a given area.

A

True

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25
Q

T/F

Phasing can be incorporated to allow for dynamic focusing

A

True

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26
Q

T/F

A lens must be used to create focusing in the elevational plane

A

True

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27
Q

T/F

Grating lobes are created by array transducers.

A

True

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28
Q

Lateral Resolution is very important in ultrasound. What fact do we associate with lateral resolution?

A) Lateral resolution and ring-down are the same
B) Lateral resolution depends on the beam diameter
C) Lateral resolution determines penetration depth
D) Lateral resolution cannot be measured in the far zone

A

B) Lateral resolution depends on the beam diameter

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29
Q

___________ is defined by the number of elements used (effective transducer width)

A

aperture

30
Q

True or false

to focus we must employ phasing

A

true

31
Q

general term for a transducer assembly consisting of a number of small, separate piezoelectric elements is :

A

an array

32
Q

the firing delay patterns of a linear phased array transducer ________

A

focus the sound beam during transmission

33
Q

the use of more active elements in order to receive reflections with a greater time of flight is called

A

dynamic aperature

34
Q

which of the following best describes the sound beam of an annular phased array transducer

A

mechanically steered and electronically focused

35
Q

which transducer creates a beam that is focused in all planes and at all depths

A

annular phased array

36
Q

annular array transducer steer the beam ________

A

mechanically

37
Q

T/F

if a probe that uses phasing, if one element malfunctions, the steering and focusing may become erratic

A

true

38
Q

information used to LOCATE reflectors in their proper position on a b-mode image display includes all of the following except

A) echo signal amplitude
B) speed of sound in the medium
C) echo arrival time
D) beam position/orientation

A

A) echo signal amplitude

39
Q

Which type of transducer?

Applying voltage pulses to all of the elements separately with small time delays

A

PHASING

40
Q

Delay pattern alters the orientation of the wavefront, causing beam to “steer” to a particular direction

A

phasing

41
Q

Transducer that scans by phasing is called a __________ array

A

phased

42
Q

Can phasing be applied to sequenced arrays to provide electronic focal control?

A

yes

43
Q

Annular focusing in all
directions both in plane
and transverse to the plane.

Linear focusing in the
imaging plane only.

A
44
Q

Beam can be focused electronically/mechanically by phasing

A

electronically

45
Q

greater curvature = close/deep focus

A

close

46
Q

Each pulse can focus at one/multiple depth requiring multiple pulses

A

one

47
Q

A linear sequenced array that emits pulses from different starting pints (sequencing) and in different directions (phasing)

A

vector array

48
Q

vector array also called

A

linear phased array

49
Q

Electronic outputs of the elements are timed so that the array “listens” at a particular depth

A

DYNAMIC FOCUSING

50
Q

DYNAMIC FOCUSING Also called

A

receiving focus depth

51
Q

Electronic focusing in the plane along the line of the transducer elements improves ___________ resolution as well as sensitivity by increasing the amount of energy in the focal zone.

A

lateral

52
Q

Beam width determined by:

3 things

A

Aperture size
Focal length
Wavelength

53
Q

Wider/narrow beam width produces a longer focal zone - better lateral resolution

A

wider

54
Q

____________ is need to control the section/slice thickness artifacts and improve the spatial resolution of the image

A

Focusing

55
Q

slice thickness focusing

Control is obtained in one of two ways:

By a fixed focal length lens attached to the array (Edelman calls this: external focusing)
The fixed lens can be set at different depths depending on transducer frequency and what depth you plan to be scanning. This is VERY important to note for small parts work:
For breast use 10mHz+ elevational plane at 1.5 cm
For vascular work 5mHz+ elevational plane at 3.0-4.0 cm

Also controlled by curving the ultrasound element (Edelman calls this: internal focusing)

A
56
Q

term (sequencing, phasing, or vector)

used to scan beam

A

sequencing

57
Q

term (sequencing, phasing, or vector)

indicates both sequencing and phasing are used to scan beam

A

vector

58
Q

term (sequencing, phasing, or vector)

used to scan, steer or focus the beam (steering is used with Doppler and color flow to change the direction of the beam to optimize the Doppler angle)

A

phasing

59
Q

All modern transducers that steer, do so by phasing

All modern transducers are focused by phasing

Mechanical transducers were NEVER able to focus (registry question)

A
60
Q

probe beam is scanned by sequencing AND phasing

A

vector

61
Q

Position (x,y) of reflector is determined by:
which crystal receives the echo
beam direction
echo arrival time
and speed of sound in the medium

Depth determined by:
time
and speed of sound in the medium

Level of brightness given to echo determined by strength of returning echo amplitude

A
62
Q

“A grouping or arrangement of parts forming a complete unit”

A

array

63
Q

Enables electronic beam steering with no mechanical motion of transducer parts

Enables electronic (dynamic) focusing and beam forming

Easier to vary electronically

A

advantages of arrays

64
Q

may be used for high intensity focused ultrasound (HIFU) to treat tumors

which type of transducer?

A

Annular

65
Q

have variable focusing in two dimensions and therefore reduces section thickness artifacts.

which type of transducer?

A

annular

66
Q

____________ array technology an important advance in ultrasonic cardiac imaging.

A

annular

67
Q

Information from areas between scan-lines is determined by averaging the amplitude of echoes of nearby scan-lines

Serves to smooth image so that individual scan-lines are not noticed

A

INTERPOLATION

68
Q

Size of the group of elements energized to produce one pulse

A

APERTURE

69
Q

Order in which the pulses are applied is called the _____________

A

firing sequence

70
Q

Beam travels perpendicular to the _____________

A

wavefront

DMS 101- Ultrasound Physics (6 decks)

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