Lesson 18 (Part 2) Flashcards Preview

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Flashcards in Lesson 18 (Part 2) Deck (30)
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1

Elevation resolution

Minimum reflector separation perpendicular to scan plane to produce separate echoes
- 3rd dimension

2

What does the beam have in elevation resolution?

Section thickness / elevational plane

3

What can elevation resolution produce?

A section thickness artifact

4

What is a section thickness artifact also known as?

Partial volume artifact

5

What do partial volume artifacts fill? (4)

1. Cysts
2. Gallbladder
3. Vessels
4. Bladder

- anechoic structures

6

What will poor elevational resolution show?

Echoes from outside the intended scan plane
- especially within anechoic structures

7

How do we fix elevational resolution artifacts? (2)

1. THI
- harmonics
2. Spatial compounding

8

What THI is better for fixing elevation resolution artifacts?

Narrower and thinner beam

9

Why are narrower and thinner beams better for THI?

Less likely to pick up echoes from other planes

10

Spatial compounding

Scanning at different angles help to deal with anechoic structures

11

Temporal resolution

Being able to separate echoes in time

12

How is poor temporal resolution visualized?

As a lag

13

Contrast resolution

Being able to separate 2 different shades of grey

14

Is having more shades of gray better or worse in contrast resolution?

Better

15

What is the useful frequency range for diagnostic applications?

2-20 MHz

16

What do higher frequencies do? (2)

1. Increase resolution
2. Decrease the maximum imaging depth

17

What happens if you have less than 2MHz?

You are losing resolution/image quality

18

What happens if you have more than 20MHz?

You will not penetrate as well

19

How can focus be achieved?

In 3D (perpendicular to the scanning plane) with a lens or curved elements

20

What does phasing need to be applied to focus the 3D electronically?

At least 3 rows of elements

21

What does electronic focusing eliminates?

The need for the lens or curved elements

22

What is 3D imaging?

Volume imaging

23

What is the down side of 3D compared to 2D?

It lags

24

What do 2D arrays have the ability to do?

Steer and focus in 2 dimensions

25

What kind of image does 1D array produce?

2D imaging

26

What kind of image does 2D array produce?

3D imaging

27

Transmit steering

Sending pulses with a delay

28

What are 2 other terms for 3D imaging?

1. Volume imaging
2. Volumetric scanning

29

What is 3D scanning mots common for?

Obstetrics
- breasts

30

What makes up 4D imaging?

3D imaging + time