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Ultrasonography > Part II > Flashcards

Part II Flashcards

1
Q

Function of the distance to the UTZ machine
Penetration into the deeper tissues [longer it takes, deeper]

A

Depth

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2
Q

Volume of returning echo/intensity
The louder the return echo, the brighter [quiter, darker]

A

Brightness

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3
Q

-provide energy to crystal
-known as the pulses
-function: control the rate of pulses emitted by the transducer or PRF & provides voltage

A

Transmitter

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4
Q

-produces and detects UTZ
-where piezoelectric effect occurs

A

Transducer

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5
Q

-range of frequency produced by a given transducer
-if broad - improve CR
-if narrow - speckle

A

Bandwidth

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6
Q

-“pressure electricity”

A

Piezoelectric

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7
Q

Explain PIEZOELECTRIC EFFECT

A

Electricity is applied to piezoelectric material → vibrates (expands & contracts) to produce mechanical sound or pressure waves → reflected waves (echoes) go back to transducer, thus converting mechanical back to electrical

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8
Q

Parts of a transducer

A

Physical housing
Electrica connections
Piezoelectric Elements
Backing Material
Acoustic Lens
Matching Layers

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9
Q

Structural support of the transducer that serves as the electrical and acoustic insulator

A

Physical Housing

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10
Q

Placed in front & back of crystal
Thin film of Ag and Au

A

Electrical Connections

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11
Q

-discovered by Jacques an Pierre (1820)
-mechanical force will induce some material to be electrically polarized

A

Piezoelectric Element

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12
Q

Piezoelectric element can be destroyed by exceeding beyond the [..]

A

Curie Temperature

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13
Q

Act as an electrode for non conducting piezoelectric element

A

Thin silver on sides

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14
Q

Reason for mechanical vibration: [..]

A

Crystal change in shape/produce sound waves

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15
Q

Piezoelectric Element
Natural: [..]
Man-made: [..]

A
  1. Quartz - first material used,
  2. Tourmaline - black mineral/prism crystals in granites and rocks
  3. Rochelle Salt/ Potassium Sodium Tartrate Tetrahydrate
  4. PZT- Lead Zirconate Titanate (also used in ceramic capacitors)
  5. Barium Titanate -piezoelectric material for microphones and transducer
  6. Lead Metaniobate - ceramics
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16
Q

-used to clean transducer because alcohol disrupts transducer

A

Ethyleneoxide

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17
Q

-reduce vibrating
-broadens the bandwidth and shorten the pulses
-improves axial resolution

A

Backing Material

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18
Q

Composition of backing material

A

Tungsten/ rubber in epoxy resin

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19
Q

Importance of backing material

A
  1. Eliminate back face vibration
  2. Control vibrations in front face
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20
Q

-located in front of transducer
-reduce the beam width of the transducer
-improv lateral resolution

A

Acoustic Lens

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21
Q

Materials of acoustic lens

A

Aluminum, Perspex, polystyrene

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22
Q

-interface between transducer and the tissue
-minimize acoustic impedance differences between the transducer

A

Matching Layer

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23
Q

-used between matching layer and patient’s skin to eliminate air pockets that could attenuate and reflect the UTZ beam
-hypoallergenic

A

Acoustic Coupling Gel

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24
Q

Types of transducer

A

Linear Array (Sequential)
Phased Array
Curvilinear Array

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25
Q

-produces beam by firing a subset of the total no of transducer elements as a group
-individual beams interact to produce collimated array
-f = 4 MHz

A

Linear Array (Sequential)

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26
Q

Linear Array example part of interests

A

Breast, thyroid, MSK, Obstetrics, Vessels

27
Q

-produces a beam from all of the transducer elements fired with fractional time delays in order to steer and focus the beam
-f = 2-7.5 MHz

A

Phased Array

28
Q

-diverge and allow wider field of view
-produce diverging images that originate in a curved arc
-f = 3.5 MHz

A

Curvilinear Array

29
Q

Curvilinear Array example part of interests

A

-abdominal and obstetrical scanning
-deep lying structures

30
Q

[utz beam properties]
-adjacent to transducer
-near field of UTZ beam
-used for UTZ imaging

A

Fresnel Zone

31
Q

[utz beam properties]
-far field
-UTZ imaging does not extend to this area

A

Fraunhofer Zone

32
Q

-region over which the beam id focused

A

Focal Zone

33
Q

Distance from transducer toward focal zone

A

Focal length

34
Q

-converging beam profile
-adjacent to the transducer face
-equal to focal distance
-at the end, region for best lateral resolution

A

Near Field

35
Q

-diverging beam profile
-Fraunhofer Zone
-UTZ intensity decrease with distance

A

Far Field

36
Q

Crystal relationship with near and far field

A

CRYSTAL NEAR FIELD FAR FIELD
NARROW decrease Increase
WIDE increase decrease

37
Q

Frequency relationship with near and far field

A

FREQUENCY NEAR FIELD FAR FIELD
INCREASE long less
DECREASE short more

38
Q

Types of Resolution

A

Spatial Resolution
Axial/Longitudinal
Lateral/Azimuthal
Elevation Resolution
Contrast Resolution
Temporal Resolution

39
Q

Ability to differentiate two closely situated objects lying along axis of beam

A

Spatial Resolution

40
Q

Ability to separate two objects along axis of beam

A

Axial/Longitudinal Resolution

41
Q

-resolution in the plane perpendicular to the beam and transducer
-determined by slice thickness
-transducer directly related to elevation

A

Elevation/Azimuth Resolution

42
Q

Ability of imaging system to differentiate between body tissues and display them as different shades of gray

A

Contrast Resolution

43
Q

Display events that occur at different times as separated images
-frame rate

A

Temporal Resolution

44
Q

Detects and amplifies voltage signals from the transducer

A

Receiver

45
Q

-ability to compensate for attenuation of the transmitted beam as the sound wave travels through tissues in the body
-signals compensate for differences in echo strength

A

Time Gain Compensation (TGC)

46
Q

-adapts the dynamic range of backscattered signal intensity (returning echoes/to correspond to the dynamic range of the display

A

Compression and Remapping of Data

47
Q

Ratio of the highest to lowest amplitude

A

Dynamic range

48
Q

Display UTZ signals depends on the different operational modes
CRT, LCD, LED

A

Image Display

49
Q

Operational Modes

A
  1. A- Mode
  2. B- Mode
  3. Real-time
  4. M-mode
50
Q

-Displays depth on the horizontal axis and echo intensity (pulse amplitude) on the vertical axis
-Displayed in CRT
-Echo, peaks and distance between various structures is measured
-Reliable in Axial Resolution

A

Static Imaging
A-mode (Amplitude)

51
Q

-shows all the tissue travelled of the beam of UTZ scan
-2D
-appear as black and white images
-shown as series of dots in CRT

A

Static Imaging
B-Mode (Brightness)

52
Q

-display changes in echo amplitude and position with time
-eval of rapidly moving structures (cardiac valves, chamber walls) -ultrasonic cardiography
-another way of displacing motion
-time on the horizontal axis and depth on the vertical axis

A

Real Time Imaging/Time Mode TM/ M-Mode (Motion)/ Position Mode PM)

53
Q

-2D, real time, gray scale
-image is built by TZ pulses sent down a series of successive line scans
-entire image is created 15-60 times per sec

A

Real Time Imaging
B-Mode

54
Q

He described Doppler Effect

A

Christian Johann Doppler

55
Q

-based on Doppler effect
-“UTS Stethoscope”

A

Doppler Mode

56
Q

-change in a frequency resulting from moving sound source

A

Doppler Effect

57
Q

Identification of blood flow vessels

A

Doppler Ultasound

58
Q

Explain STATIONARY TARGET (Doppler Effect)

A

-If reflecting interface is stationary, the backscattered UTS has the same frequency or wavelength as transmitted sound
-reflected and transmitted energy as equal

59
Q

Explain TARGET MOTION towards transducer

A

-difference in reflected and transmitted frequencies in greater than zero

60
Q

-use color map to display information based on the detection of frequent shifts from moving targets
-determine vessel if artery of vein
-shows arterial or venous supply of organ
-full of noise, limited sensitivity

A

Color Flow Doppler Imaging (CD)

61
Q

BART

A

Blue away, Red towards

62
Q

-uses color map to show distribution of the power/amplitude of the Doppler signal
-flow direction and velocity info are not provided
-noise is reduced with improved sensitivity for flow detection

A

Power Mode Doppler

63
Q

-reduces noice and scatter of image
-improves spatial resolution

A

Tissue Harmonic Imaging

64
Q

-combines images contained by isonating the target from multiple angles
-improves contrast
-speckle

A

Spatial Compunding

Ultrasonography (10 decks)

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