SPI Boards Practice Last

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created 5 years ago by Annabelle
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updated 4 years ago by Annabelle
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1

Variable

Pressure

Density

Distance

temperature

2

Synonyms Axial Resolution

LARRD

longitudinal

axial

radial

range

Depth

3

Synonyms Lateral Resolution

LATA

Lateral

azimuthal

transverse

angular

4

How do you get better axial resolution?

  • 1/2 SPL
  • shorter pulses
    • Higher frequency
    • less ringing - backing
5

How does the far field diverge less (shorter NZL)?

high frequency = smaller beam = better lateral res

6

Deep Focus

frequency?

diameter?

Higher frequency

larger diameter crystal

7

Demodulation

Rectification and Smoothing

8

typical frame rate

Between 5 Hz and 40 Hz

9

If the thickness of the 2 substances forming the interface is increased then the amount of beam reflected is…?

unchanged

10

Dynamic Range

contrast

11

Top of head to ankle

CP + HP

BP + HP

-30

0

50

75

100

12

Why are Contrast agents useful?

strong reflectors

13

Where is pre amplification done?

near element

14

What does the Receiver do?

Amplification - gain

Compensation – TGC

Compression – grayscale mapping – Syn. Dynamic range

Demodulation

  • Rectification = negV to posV
  • Smoothing = enveloping

Reject – threshold, suppression – gets rid of weak echoes

15

Amplification?

Gain

16

Compensation

TGC

17

Compression

grayscale mapping – Syn. Dynamic range

18

Rectification

negative Voltage to positive Voltage

A part of Demodulation

19

Smoothing

enveloping

A part of Demodulation

20

Reject

Synonyms - threshold, suppression

gets rid of weak echoes

21

threshold

Synonyms - Reject, suppression

gets rid of weak echoes

22

suppression

Synonyms - threshold, Reject

gets rid of weak echoes

23

Display

    • Preprocessing before storage in scan converter
    • A to D
    • Write magnification
  • Scan converter –
    • Read Magnification = same pixels, bigger pixels
    • D to A
    • Postprocessing
24

Which comes first

analog to digital

digital to analog

Analog to Digital

25

Write magnification

more pixels, same size pixels

26

What happens before storage into the Scan converter?

  • Preprocessing
  • A to D
  • Write magnification
27

What happens before storage into the Scan converter?

  • Read Magnification = same pixels, bigger pixels
  • D to A
  • Postprocessing
28

Read Magnification

same pixels, bigger pixels

29

What happens to PRF going deeper?

lower PRF

30

What happens to PRF going superficial?

higher PRF

31

Typical input voltage

10 μvolts

32

Bit

grayshades - contrast resolution

33

Pixel

image detail - spatial resolution

34

Which transducer have the best elevational resolution?

1 ½

subdicing from top to bottom

35

What is the shape of the linear switched array?

rectangular

36

What is the shape of the convex transducer?

blunted sector

37

What is the shape of the vector transducer?

trapezoidal

38

What is the shape, steering and focus of the mechanical transducer?

sector, mechanical, fixed

39

What is the shape, steering and focus of the annular array transducer?

sector, mechanical, electronic

40

Stable Cavitation causes

shear stress

41

Transient cavitation causes

shock waves and high temps

42

What are synonyms of transient cavitation?

normal, inertial

43

Unfocused SPTA =

100 mW/cm2

.1 W/cm2

44

Focused SPTA =

1000 mW/cm2

1 W/cm2

45

mechanistic

cause effect

46

emprical

exposure response

47

Autocorrelation

Spectral analysis

faster

48

Cosine

  • 90 = 0
  • 60 = .5
  • 0 = 1
49

Doppler grayscale

# RBCs

50

Coaptation

vessel collapse

51

Velocity mode Vs Variance mode

Velocity mode = direction/ speed

Variance mode = direction/ speed + laminar from turbulent

52

Comet trail =

reflection

53

Aliasing =

high frequency, large gate, fast blood (Not in CW)

54

Focal enhancement =

focusing

55

Shadow =

high attenuation

56

Acoustic Speckle =

interference

57

Divergence / large diameter / high frequency

less divervence

58

Beam uniformity coefficient

SP/SA factor

spread of beam

1 or more

unitless

59

tissue heating intensity

SPTA

60

intensity of a continuous wave what is =

TA = PA

SPTA = SPPA

SATA = SAPA

61

Im

averaged over most intense half cycle

62

Pa

on time average

63

Intensity high to low

SPTP

Im

SPPA

SPTA

SATA

64

Rayleigh =

f4

65

Half value =

medium and frequency

66

Impedance of ST =

19 megaRayls

67

Reflection at 90o

must have different impedances

68

Refraction

oblique incidence and different speeds

69

Snell’s =

transmission with oblique incidence

70

CW PZT thickness =

2NZL

71

Water speed

1480

72

blood / liver speed

1560

73

mucles speed

1600

74

tendon speed

1700

75

bone speed

4080

76

fat speed

1450