Ch. 13 Physics: Real- Time imaging

Question 1

True or false:
two-dimensional images were created through a time-consuming process called static scanning and is still used today.

Answer 1

False
Today all modern ultrasound instruments are capable of real-time imaging.

Question 2

describes a systems ability to create numerous frames (images) each second.

Answer 2

Frame rate

Question 3

Frame rate is determined by …..

Answer 3

Sound speed within the medium – most important

Imaging depth

Question 4

Frame Rate is ___________ to Temporal Resolution

Answer 4

Proportional

Question 5

What is the typical frame rate per second?

Answer 5

30 - 60 frames per second

Question 6

Maximum imaging depth determines frame rate with speed of sound in soft tissue considered at a constant ________.

Answer 6

1.54km/s

Question 7

What is frame rate measured in?

Answer 7

Hz

Question 8

Accuracy in time – the ability to precisely position moving structures from instant to instant

Answer 8

Temporal resolution

Question 9

Temporal resolution is determined by what?

Answer 9

Frame rate

Question 10

_______ frame rate improves temporal resolution

Answer 10

High

Question 11

_______ frame rate reduces temporal resolution

Answer 11

Low

Question 12

If it takes 1/30 of a second to make a frame, then the frame rate is ……

Answer 12

30 frames per sec, or 30 Hz

T frame x frame rate = 1

Question 13

Is the temporal resolution controlled or not controlled by the sonographer?

Answer 13

Controlled

Question 14

How is temporal resolution controlled?

Answer 14

Imaging depth

Number of pulses per frame

Question 15

Imaging depth and frame rate are _________ related

Answer 15

inversely

Question 16

What is the formula for image depth?

Answer 16

Tframe = # pulses x PRP

Question 17

Shallow depths allow for a _______ frame rate

Answer 17

higher

Question 18

Deeper imaging requires more time to create and results in ______ frame rate

Answer 18

slower

Question 19

To maintain better temporal resolution, we would want the most ________ image.

Answer 19

Shallow

Question 20

_________________ also affects the frame rate since the more pulses needed to create an image would take more time….then the temporal resolution would decrease.

Answer 20

Pulses per image

Question 21

What are the three factors that determine the number of pulses needed to create the image?

Answer 21

Number of pulses per scan line (multi-focus vs. single focus)

Sector size

Line density

Question 22

What increases lateral resolution, but only at a trade off reducing temporal resolution?

Answer 22

Multi-focus

Question 23

Also known as field of view

Answer 23

Sector size

Question 24

By expanding the ___________, more pulses are required to create an image so temporal resolution decreases

Answer 24

sector size

Question 25

The number of scan lines in the sound beam.

Answer 25

Line density

Question 26

So what do you think happens to the temporal resolution with
increased line density?

Answer 26

It would decrease

Question 27

what would happen to our spatial resolution with increased line density?

Answer 27

It would increase

Question 28

More lines = increased detail (spatial resolution), but _____ frame rate (decreased temporal resolution)

Answer 28

slower

Question 29

Few lines = decreased detail (spatial resolution), but _____ frame rate (increased temporal resolution)

Answer 29

faster