Chapter 18 Flashcards

(43 cards)

1
Q

Resolution

A

The ability to image fine detail

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

____ resolution is better

A

Smaller

Tinier details can be discerned

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

If two reflectors are not seperated sufficiently they produce

A

Overlapping echoes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Axial resolution aka

A

Longitudinal, radial, depth and range

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Axial resolution is

A

Minimum reflector seperation along scan line to produce separate echoes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Axial resolution = ____ mm

A

2mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Structures place 1 mm apart will be seen as a

A

Single structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Axial resolution equation

A

AR= SPL/2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

The smaller the AR the

A

Better

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

To improve AR we need to

A

Reduce SPL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Lateral resolution aka

A

Angular, transverse, azimuthal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Lateral resolution is

A

Minimum reflector seperation perpendicular to scan line to produce separate echoes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Lateral resolution occurs when _____=____

A

LR=Wb

Lateral resolution = width of beam

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

LR=3mm

A

Reflector seperation is less than Wb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

LR=1mm

A

BEAM IS NARROWER THAN REFLECTOR SEPERATION

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

WHAT IS BETTER SMALL OR LARGE LR

A

Smaller

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

LR is improved by

A

Reducing the wb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Elevation resolution

A

Minimum reflector separation perpendicular to scan plane to produce separate echoes

Operates in 3 dimension

19
Q

Elevational resolution has ____

A

Slice thickness aka section thickness / elevational plane

20
Q

Elevational resolution can preoduce

A

Section thickness artifact aka partial volume artifact

Can fill in cysts or other anechoic structures

21
Q

Poor elevation resolution will show

A

Echoes from outside the intended scan plane

Especially within anechoic structures

22
Q

HOW DO WE FIX elevational resolution artifact

A

THI—> narrower and thinner beam

Less likely to pick up echoes from other plane

Spatial compounding

23
Q

AR is less than _____mm to distinguish two seperate objects

24
Q

Temporal resolution

A

Being able to separate echoes in time

Poor temporal resolution is visualized as lag

25
Contrast resolution
Being able to separate two different shades of grey
26
Usefull frequency range
2 to 20 MHz
27
Higher freq increase _____ and decrease ________
Resolution Max imaging depth
28
Up to _____ Mhz can be used for ophthalmologic, dermatologic, and intravascular imaging
50 MHz
29
Focus can be achieved in the third dimension by
Lens or curved elements
30
What is third dimension
Perpendicular to the scanning plane
31
How many rows of elements needed for phasing to be applied to focus the third dimension electronically
At least three
32
Electronic focusing eliminates the need for
A lens or curved elements
33
2D arrays have the ability to _____ and _____ in two dimensions
Steer and focus
34
1D array =
2D imaging
35
2D array ->
3D imaging
36
3D imaging aka
Volume imaging | Volumetric scanning
37
3D imaging mainly used for
OBSTETRICS AND BREAT
38
4D imaging =
3D imaging + time
39
Echoes arriving to the transducer can be ________ as well
Delayed or phased
40
Reception steering
Listening from a particular direction
41
Dynamic focusing
Continual change of the focus with increasing depth
42
Dynamic aperture
As the focus continues to change during echo reception, the aperture will increase to maintain a constant focus with
43
Annular arrays
Concentric rings Piezoelectric material carved out in rings Go from smallest to largest Not used anymore