Week 6 - Range, Displays, Dynamic range, Harmonics, and Contrast

Question 1

In order to create a dot on the image, a pulse of sound must what?

Answer 1

travel to a reflector and return to the transducer

Question 2

The time it takes to go and return from a reflector is known as what?

Answer 2

Time of Flight

Question 3

Time of Flight is what?

Answer 3

the round trip of a pulse

Question 4

The total distance a beam and echo travels is what?

Answer 4

twice the depth of the reflector

Question 5

What is the speed of US?

Answer 5

1.54 mm/µsec

Question 6

What MUST you do to accurately calculate the reflector depth?

Answer 6

divide the round-trip distance by 2

Question 7

How long does it take US to travel 1 cm?

Answer 7

13 µsec

Question 8

4 cm would take how long to travel?

Answer 8

52 µsec

Question 9

How can you adjust the amount of time between pulses?

Answer 9

by adjusting the depth

Question 10

What do PRP and PRF stand for?

Answer 10

pulse repetition period, pulse repetition frequency

Question 11

What is PRP?

Answer 11

the length of time between pulses

Question 12

Relation. PRP and depth.

Answer 12

Directly

Question 13

What is PRF?

Answer 13

the number of pulses sent per sec (Hz)

Question 14

Relation. PRF and depth.

Answer 14

Inversely

Question 15

As depth increases, the frequency of pulses __________.

Answer 15

decreases, since they need more time to travel

Question 16

A low PRF is (GOOD or BAD). Why?

Answer 16

BAD, because something may have been missed by sending fewer pulses which results in less information

Question 17

A high PRP is (GOOD or BAD). Why?

Answer 17

BAD, because more time between pulses means less information resulting in something being missed

Question 18

You should use the _________ depth when scanning.

Answer 18

least amount of

Question 19

You should use the _________ depth when scanning.

Answer 19

least amount of

Question 20

What are 3 major ways to display US image data?

Answer 20

A mode, B mode, M mode

Question 21

What does A mode display?

Answer 21

the AMPLITUDE of each echo on a graph

Question 22

In A mode, the Y axis measures __________ and the X axis measures ___________.

Answer 22

amplitude, depth

Question 23

What does B mode display?

Answer 23

gray scale imaging

Question 24

In B mode, the Y axis is the ___________ of the reflector, and the X axis is ______________.

Answer 24

depth, each point the transducer sent a soundwave

Question 25

What does brightness represent in B mode?

Answer 25

the strength of the echo

Question 26

What is M mode used to measure and how is it displayed?

Answer 26

M mode measures the motion of a structure (esp. the heart) and it is displayed with wavy and straight lines.

Question 27

Dynamic range describes what?

Answer 27

the number of grays available for imaging

Question 28

What changes the dynamic range?

Answer 28

Compression

Question 29

A __________ dynamic range = many shades of gray and _________ contrast. This is helpful to see differences in _________.

Answer 29

wide, low, plaque

Question 30

A __________ dynamic range = few shades of gray and _________ contrast. This is helpful to see ____________.

Answer 30

narrow, high, vein compressions

Question 31

Harmonic images are created from reflections that are __________ the frequency of the probe.

Answer 31

twice

Question 32

A 2 MHz fundamental frequency would create a Harmonic frequency of __________.

Answer 32

4 MHz

Question 33

The best use of harmonic imaging is in ___________.

Answer 33

Deeper structures

Question 34

Strength of the harmonic wave ___________ as sound travels.

Answer 34

increases

Question 35

Microbubbles are ___________, and they are used to do what?

Answer 35

contrast agents, create stronger reflectors

Question 36

Microbubbles are used to see ___________ better in small spaces

Answer 36

blood flow

Question 37

Microbubbles have a _____________ behavior, meaning that they do what?

Answer 37

non-linear, grow and shrink when hit with soundwaves

Question 38

Low _______ and high _________ will increase harmonics.

Answer 38

frequency, amplitude

Question 39

The mechanical index estimates the amount of what?

Answer 39

harmonics created

Question 40

What is a common, short-lived contrast agent?

Answer 40

Agitated Saline