11 Contrast, Spatial + Temporal Resolution

Question 1

What is contrast resolution?

Answer 1

Visualizing a variety of gray shades in an image

Few grade shades = poor contrast resolution

Question 2

What is spatial resolution?

Answer 2

Visualizing detail in an image

Limited detail = poor spatial resolution

Question 3

What is real-time imaging?

Answer 3

The production of a motion picture

Question 4

What is temporal resolution?

Answer 4

The ability to accurately locate moving structures at any particular instant of time

Question 5

What is temporal resolution determined by?

Answer 5

Frame rate

More images/sec improves temporal resolution

Question 6

What is the typical value of temporal resolution?

Answer 6

20–100 Hz

Question 7

What are the two factors that determine frame rate?

Answer 7

Imaging depth
# of pulses per image

Question 8

What are two factors that limit frame rate?

Answer 8

The speed of sound in medium

Imaging depth

Question 9

What is a fundamental limitation of temporal resolution?

Answer 9

Speed

Question 10

What are four settings that a sonagrapher controls that affect temporal resolution?

Answer 10

Maximum imaging depth
# of pulses per scanline
Sector size
Line density

Question 11

List 2 questions to determine the effect on temporal resolution.

Answer 11

Is the image shallower?

Is the image comprised of fewer pulses?

Question 12

With regard to maximum imaging depth, what will create a frame in less time?

Answer 12

Shallow depth of view makes a frame faster

Question 13

With regard to pulses per scan line, which will create a frame with fewer pulses?

Answer 13

Single focus systems use fewer pulses

Question 14

What will create the best temporal resolution?

Answer 14

Single focusing
Narrow sector
Low line density
Higher frame rate
Shallow imaging
Fewer pulses per image

Question 15

How does multi-focus affect lateral and temporal resolution?

Answer 15

Improves lateral resolution

Reduces frame rate and degrades temporal resolution

Question 16

With regard to sector size, what will create a frame with fewer pulses?

Answer 16

Smaller sector angle creates images with fewer pulses

Question 17

With regard to line density, what will create a frame with fewer pulses?

Answer 17

Low line density images use fewer pulses

Question 18

What does lower line density degrade?

Answer 18

Spatial resolution

Question 19

What is line density in a sector image?

Answer 19

Number of scan lines per degree of sector

Question 20

What does improved temporal resolution degrade?

Answer 20

Image quality

Question 21

What is Tf?

Answer 21

Time required to make a frame

Question 22

What is the relationship between Tf and frame rate?

Answer 22

They are reciprocals

Tf x FR = 1