Lesson 18 (Part 1)

Question 1

Resolution (2)

Answer 1

1. To create a better picture

2. Being able to separate distinct echoes

Question 2

What are 3 examples imaging resolution?

Answer 2

1. Detail/spatial
   - transducer
2. Contrast
   - instrument
3. Temporal
   - instrument

Question 3

What kind of resolution is better?

Answer 3

Smaller

- tinier details can be discerned

Question 4

What happens if 2 reflectors are not separated sufficiently?

Answer 4

They produce overlapping echoes

- smear

Question 5

What is axial resolution also known as? (4)

Answer 5

1. Longitudinal
2. Radial
3. Depth
4. Range

Question 6

Axial resolution

Answer 6

Minimum reflector separation along scan lines to produce separate echoes

Question 7

What happens to the image when distance between the structures is greater than the axial resolution?

Answer 7

It will appear as a single structure

- smear

Question 8

What happens to the image when the distance between the structures is lower than the axial resolution?

Answer 8

You will get separate structures

Question 9

What is the formula for axial resolution?

Answer 9

AR = SPL/2

• AR = axial resolution
• SPL - spatial pulse length

Question 10

How do you get the best axial resolution?

Answer 10

Smaller SPL

Question 11

What is the unit for axial resolution?

Answer 11

mm

Question 12

How do we reduce SPL? (3)

Answer 12

1. Reducing the number of cycles
2. Reducing the wavelength
3. Increase frequency

Question 13

How do you reduce the number of cycles?

Answer 13

Applying damping

Question 14

What does increasing frequency affect?

Answer 14

Penetration

Question 15

What is lateral resolution also known as? (3)

Answer 15

1. Angular
2. Transverse
3. Azimuthal

Question 16

Lateral resolution

Answer 16

Minimum reflector separation perpendicular to scan line to produce separate echoes
- horizontal line

Question 17

What is the formula for lateral resolution?

Answer 17

LR = Wb

• LR = lateral resolution
• Wb = width of beam

Question 18

What is the unit for lateral resolution?

Answer 18

mm

Question 19

What happens in lateral resolution of the resolution is too high?

Answer 19

You get a smearing effect

Question 20

What happens if the beam is narrower than reflector separation in lateral resolution?

Answer 20

You get 2 distinct structures

Question 21

What is the lateral resolution at the focus?

Answer 21

Same as what is the beam width at the focus

Question 22

What is the formula for beam width?

Answer 22

1/2 of the aperture

Question 23

What is the best lateral resolution?

Answer 23

The smaller the better

Question 24

How is lateral resolution improved?

Answer 24

By reducing beam width

Question 25

How can you reduce the beam width in lateral resolution?

Answer 25

By adjusting the focus

- making it more narrower

Question 26

Where can you move the focus?

Answer 26

Near zone length

- NZL

Question 27

Where cant you move the focus?

Answer 27

Far zone length

Question 28

What can you change in the FZL?

Answer 28

Aperture size