Lesson 17 (Part 2) Flashcards Preview

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Flashcards in Lesson 17 (Part 2) Deck (37)
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1

Spatial compounding

Hitting the same object from different angles

2

What is the benefit of spatial compounding? (3)

1. Clears out cysts
2. Sharpens borders
3. Smoother images

3

What does spatial compounding have more of?

More pulses per image

4

Sector image

Phasing of a very small group of elements

5

What can sector imaging be used to assess?

Large areas through very small windows

6

Vector array

Phasing can be applied to each element group in a linear sequenced array

7

What do vector array's do?

Steer pulses in various directions

8

How does vector array initiate pulses?

At various starting points across the array

9

What makes up a linear array? (2)

Linear array + phased array

10

What does a vector array have?

A flat top

11

What is vector array a combination of? (2)

1. Sequencing
2. Phasing

12

What is another word for sector?

Widescreen

13

What is a sector used to measure?

Larger organs

14

What is vector array?

Phasing applied to a linear sequenced array

15

What is kept the same for each group in vector array?

Delays

16

How are beams sent out in vector array?

In an angled direction

17

What kind of display is vector array?

Parallelogram shaped display

18

When is vector array used?

In Doppler ultrasound

19

Are all elements if a phased array used to generate all pulses?

No

20

What are smaller groups of arrays used for?

Shorter focal lengths

21

What are larger groups of array used for?

For foci located at increasing depths

22

Side lobes

Usually represent unwanted radiation in undesired directions

23

Grating lobes

Are the maxima of the main beam, as predicted by the pattern multiplication theorem

24

What kind of interactions come from grating lobes?

Interelement interactions

25

What can happen in grating lobes?

It can hit a strong reflector and produce strong echoes

26

What are strong reflector examples the grated lobe can hit? (3)

1. Diaphragm
2. Gas
3. Fetal bone

27

What do grating lobes show as?

Artifacts

28

What do grating lobes look like?

Amniotic bands

29

How do you fix grating lobes? (3)

1. Apodization
2. Subdicing
3. THI

30

Apodization

Optical filtering technique