Week 13- 2 Dimensional imaging Part 2

Question 1

What does resolution refer to?

Answer 1

refers to the accuracy in imaging.

Question 2

What is slice thickness?

Answer 2

elevational thickness

Question 3

Image resolution deals with three dimensional space how?

Answer 3

1. Shallow to deep
2. side to side
3. above to below the imaging plane.

Question 4

What shape active element creates the best elevational resolution?

Answer 4

Disc-shaped crystals

Question 5

What does Elevational resolution or Slice thickness refer to?

Answer 5

The height of the beam.

Question 6

What axis does Elevation sit on?

Answer 6

z axis

Question 7

Elevational resolution is best with what kind of crystal?

Answer 7

smaller crystals

Question 8

What transducer has the best elevational resolution?

Answer 8

Annual phased array transducer

Question 9

What are side lobes?

Answer 9

off-axis sound beams made by single-element transducers.

Question 10

Where are side lobes found?

Answer 10

in the far field.

Question 11

Do side lobes degrade or make lateral resolution better?

Answer 11

Degrades lateral resolution.

Question 12

What are grating lobes?

Answer 12

Off axis sound beams that extend outside of the main beam.

Question 13

What kind of transducers create grating lobes?

Answer 13

Array Transducers

Question 14

What is apodization?

Answer 14

the altering of electrical spike voltages that reduce lobe strength. Reduces Side and grating lobes.

Question 15

Side lobes

Answer 15

1. sound is omnidirectional
2. Some sound is directed off the main beam
3. Structures within side lobes can generate reflections that create artifacts.
4. Degrades Lateral resolution

Question 16

Grading Lobes

Answer 16

1. Sound is omnidirectional
2. Sound is directed off the main beam.
3. Structures with grating lobes can generate reflections that create artifacts.
4. Degrades Lateral resolution

Question 17

What are 3-D images made of?

Answer 17

Voxels

Question 18

What 3 imaging planes does 3-D imaging use?

Answer 18

1. Axial
2. Lateral
3. Elevational

Question 19

What is Subdicing?

Answer 19

Active elements are cut into smaller pieces called sub elements.

Question 20

What does subdicing reduce?

Answer 20

reduces grating lobes.

Question 21

What is the aperature?

Answer 21

the “listening hole” or the number of elements used to create sound beams or to receive reflected echoes.

Question 22

What does dynamic aperture change?

Answer 22

changes the shape of the sound beam.

Question 23

Which of the following is an advantage of 1 1/2 D (dimensional) arrays?

Answer 23

reduced slice thickness

Question 24

True or False, linear arrays create sound beams that are parallel and are evenly spaced at all depths.

Answer 24

True

Question 25

True or False: A machine that displays a 2D image and Doppler is called a duplex scanner.

Answer 25

TRUE

Question 26

Which of the following best describes the sound beam of an annular phased array transducer?

Answer 26

mechanically steered and electronically focused

Question 27

The firing delay patterns of a linear phased array transducer:

Answer 27

focus the sound beam during transmission

Question 28

What is a typical value for the electrical signal delays in a curvilinear phased array transducer?

Answer 28

10 ns

Question 29

Which transducer creates a beam that is focused in all planes and at all depths?

Answer 29

annular phased array

Question 30

Which transducer will improve elevational resolution?

Answer 30

1 1/2 dimensional array

Question 31

What kind of transducer produces side lobes?

Answer 31

Single element transducers. Mechanical

Question 32

What kind of transducers create grating lobes?

Answer 32

Array transducers.