Lesson 18 (Part 2)

Question 1

Elevation resolution

Answer 1

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

Question 2

What does the beam have in elevation resolution?

Answer 2

Section thickness / elevational plane

Question 3

What can elevation resolution produce?

Answer 3

A section thickness artifact

Question 4

What is a section thickness artifact also known as?

Answer 4

Partial volume artifact

Question 5

What do partial volume artifacts fill? (4)

Answer 5

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

• anechoic structures

Question 6

What will poor elevational resolution show?

Answer 6

Echoes from outside the intended scan plane

- especially within anechoic structures

Question 7

How do we fix elevational resolution artifacts? (2)

Answer 7

1. THI
   - harmonics
2. Spatial compounding

Question 8

What THI is better for fixing elevation resolution artifacts?

Answer 8

Narrower and thinner beam

Question 9

Why are narrower and thinner beams better for THI?

Answer 9

Less likely to pick up echoes from other planes

Question 10

Spatial compounding

Answer 10

Scanning at different angles help to deal with anechoic structures

Question 11

Temporal resolution

Answer 11

Being able to separate echoes in time

Question 12

How is poor temporal resolution visualized?

Answer 12

As a lag

Question 13

Contrast resolution

Answer 13

Being able to separate 2 different shades of grey

Question 14

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

Answer 14

Better

Question 15

What is the useful frequency range for diagnostic applications?

Answer 15

2-20 MHz

Question 16

What do higher frequencies do? (2)

Answer 16

1. Increase resolution

2. Decrease the maximum imaging depth

Question 17

What happens if you have less than 2MHz?

Answer 17

You are losing resolution/image quality

Question 18

What happens if you have more than 20MHz?

Answer 18

You will not penetrate as well

Question 19

How can focus be achieved?

Answer 19

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

Question 20

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

Answer 20

At least 3 rows of elements

Question 21

What does electronic focusing eliminates?

Answer 21

The need for the lens or curved elements

Question 22

What is 3D imaging?

Answer 22

Volume imaging

Question 23

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

Answer 23

It lags

Question 24

What do 2D arrays have the ability to do?

Answer 24

Steer and focus in 2 dimensions

Question 25

What kind of image does 1D array produce?

Answer 25

2D imaging

Question 26

What kind of image does 2D array produce?

Answer 26

3D imaging

Question 27

Transmit steering

Answer 27

Sending pulses with a delay

Question 28

What are 2 other terms for 3D imaging?

Answer 28

1. Volume imaging

2. Volumetric scanning

Question 29

What is 3D scanning mots common for?

Answer 29

Obstetrics

- breasts

Question 30

What makes up 4D imaging?

Answer 30

3D imaging + time