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Sonographic Topics > Chapter 3: Imaging Principles and Instrumentation > Flashcards

Chapter 3: Imaging Principles and Instrumentation Flashcards

1
Q

A mode

A

amplitude mode

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2
Q

x- axis =

A

depth

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3
Q

y-axis =

A

strength of reflector

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4
Q

B mode

A

Brightness mode

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5
Q

displays brightness of echoes at dots of varying brightness

A

B mode

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6
Q

very strong reflectors

A

hyperechoic

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7
Q

very weak reflectors

A

hypoechoic

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8
Q

no return echo

A

anechoic

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9
Q

amplitude of B mode is represented on the ____

A

z-axis

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10
Q

states that the distance to the reflector is equal to the propagation speed multiplied by the round trip time

A

range equation

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11
Q

d=0.77t

A

range equation

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12
Q

it takes __s for sound to travel to a depth of 1 cm and return

A

13

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13
Q

motion of reflectors on a single scan line

A

m mode

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14
Q

m mode

A

motion mode

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15
Q

one scan line represented over time with depth along the y-axis and time along the x-axis

A

M-mode tracing

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16
Q

controls timing of signals sent to individual elements for steering and focusing of the beam

A

beam former

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17
Q

determine sequence of voltage pulses sent to the individual elements in an array transducer

A

beam former

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18
Q

used to decrease risk of grating lobes; works by decreasing strength of voltage pulse sent to outermost elements

A

apodization

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19
Q

transmitter or pulse generator

A

pulser

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20
Q

controls strength, or amplitude, of electricity striking the elements, as well as the PRF and PRP

A

pulser

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21
Q

controls amount of power entering patient

A

output power

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22
Q

ALARA

A

as low as reasonably achievable

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23
Q

sends a series of encoded pulses to form one scan line instead of the one pulse per scan line technique; allows for multiple focal zones, improved penetration, speckle reduction, B-flow imaging, and improved contrast resolution

A

coded excitation

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24
Q

soft tissue imaged at various frequencies and averaged

A

frequency compounding

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25
Q

part of the machine responsible for controlling the timing of the echo

A

master synchronizer

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26
Q

tells pulser to send out a pulse and pays attention to when echoes come back to determine range

A

master synchronizer

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27
Q

the deeper a wave travels, the more deformed it becomes

A

nonsinusoidal

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28
Q

multiples of the fundamental frequency

A

tissue harmonic imaging

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29
Q

If the harmonic signal is very narrow, this results in _____ lateral resolution

A

excellent

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30
Q

also referred to as signal processor

A

receiver

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31
Q

increases the relatively weak signal coming from the transducer

A

preamplification

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32
Q

overall gain; increases or decreases the strength of all the returning echoes equally

A

amplification

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33
Q

also referred to as TGC; compensates for attenuation

A

compensation

34
Q

needed to decrease difference between largest and smallest amplitudes within signal (dynamic range)

A

compression

35
Q

Compression is ______ related to dynamic range

A

inversely

36
Q

processes signal to make it easier for machine to handle

A

demodulation

37
Q

Two components of demodulation

A

rectification
smoothing

38
Q

turns negative voltages into positive voltages

A

rectification

39
Q

wraps an envelope around signal to make it less “bumpy”

A

smoothing

40
Q

discards signal amplitudes below a certain threshold to reduce image noise

A

rejection

41
Q

ensures electrical signals travel in the correct direction

A

transmit/receive switch

42
Q

ensures the pulser voltages go to the transducer, and the received voltages from the transducer go to the signal processor

A

transmit/receive switch

43
Q

part of the machine that makes gray-scale imaging possible

A

scan converter

44
Q

responsible for storage of image data

A

scan converter

45
Q

utilizes only zeroes and ones instead of numbers 0 through 9
0 represents “off” - black echo
1 represents “on” - white echo

A

binary system

46
Q

black and white images

A

bistable

47
Q

consists of analog to digital converter, computer memory, digital to analog converter

A

scan converter

48
Q

occurs in A-to-D converter, incoming signals assigned shades of gray based on their amplitudes, image still “live”

A

preprocessing

49
Q

machine guesses what pixel should be placed between gaps in scan lines

A

fill-in interpolation

50
Q

smallest amount of computer memory

A

Bit

51
Q

8 bits =

A

1 byte

52
Q

The number of bits determines:

A

the number of shades of gray possible

53
Q

Number of shades of gray =

A

2x number of bits

54
Q

picture element

A

pixel

55
Q

smallest part of any picture

A

pixel

56
Q

More pixels = better _____ resolution

A

spatial

57
Q

volume element

A

voxel

58
Q

signal converted back to analog form so it can be sent to PACS

A

D-to-A converter

59
Q

preprocessing function, enlarges image by redrawing it

A

write zoom

60
Q

postprocessing function, enlarges images by magnifying pixels

A

read zoom

61
Q

use of an electron gun to send a stream of electrons toward a phosphor coated screen; beam steered via use of magnetic reflector coils

A

Cathode Ray tube

62
Q

works with a light source positioned behind two polarized filters with liquid crystals sandwiched between them; twisting or untwisting of the crystal determines if light shines through to face of display

A

LCD or flat panel display

63
Q

uses RAID to store large quantities of data

A

PACS

64
Q

imaging computers that use a standardized format to communicate with each other and exchange data

A

DICOM

65
Q

echoes on the screen that are not representative of actual anatomic features or occur when there are anatomic structures in the body that are not displayed on the screen

A

imaging artifacts

66
Q

occurs when the sound bounces back and forth between two close together strong specular reflectors

A

reverberation

67
Q

“step ladder” like appearance

A

reverberation

68
Q

can be caused by small structures like surgical clips or adenomyomatosis within gallbladder wall

A

comet tail

69
Q

caused by sound interacting with small air bubbles, causing the bubbles to vibrate

A

ring-down artifact

70
Q

occurs when the sound is aimed toward a large specular reflector that acts like a mirror and directs some of the sound in a direction other than back to the transducer

A

mirror image artifact

71
Q

causes artifacts as the beam is directed away from the path in which it was originally intended to go

A

refraction

72
Q

seen when sound strikes a curved reflector

A

edge shadowing

73
Q

eliminates beam hits structure at different angles

A

spatial compounding

74
Q

Side lobes occur with _____ transducers

A

all

75
Q

Grating lobes occur with _____ transducers

A

linear

76
Q

tissue propagation speed less than 1540 m/s, objects are

A

displayed too far away

77
Q

tissue propagation speed more than 1540 m/s, objects are

A

displayed too close

78
Q

occurs when sound travels through an area of higher attenuation compared with surrounding tissue

A

shadowing

79
Q

occurs from sound traveling through areas of lower attenuation

A

acoustic enhancement

80
Q

occurs because the beam scanned through both the cyst and soft tissue adjacent to the cyst, causing both to appear on the image

A

slice-thickness artifact

81
Q

presence of electrical equipment near the ultrasound; causes arc-like bands that move across the screen as long as the machine is in the proximity of unshielded equipment

A

electrical interference

82
Q
A

Sonographic Topics (35 decks)

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