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

1
Q

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

A

travel to a reflector and return to the transducer

2
Q

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

A

Time of Flight

3
Q

Time of Flight is what?

A

the round trip of a pulse

4
Q

The total distance a beam and echo travels is what?

A

twice the depth of the reflector

5
Q

What is the speed of US?

A

1.54 mm/µsec

6
Q

What MUST you do to accurately calculate the reflector depth?

A

divide the round-trip distance by 2

7
Q

How long does it take US to travel 1 cm?

A

13 µsec

8
Q

4 cm would take how long to travel?

A

52 µsec

9
Q

How can you adjust the amount of time between pulses?

A

by adjusting the depth

10
Q

What do PRP and PRF stand for?

A

pulse repetition period, pulse repetition frequency

11
Q

What is PRP?

A

the length of time between pulses

12
Q

Relation. PRP and depth.

A

Directly

13
Q

What is PRF?

A

the number of pulses sent per sec (Hz)

14
Q

Relation. PRF and depth.

A

Inversely

15
Q

As depth increases, the frequency of pulses __________.

A

decreases, since they need more time to travel

16
Q

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

A

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

17
Q

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

A

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

18
Q

You should use the _________ depth when scanning.

A

least amount of

19
Q

You should use the _________ depth when scanning.

A

least amount of

20
Q

What are 3 major ways to display US image data?

A

A mode, B mode, M mode

21
Q

What does A mode display?

A

the AMPLITUDE of each echo on a graph

22
Q

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

A

amplitude, depth

23
Q

What does B mode display?

A

gray scale imaging

24
Q

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

A

depth, each point the transducer sent a soundwave

25
Q

What does brightness represent in B mode?

A

the strength of the echo

26
Q

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

A

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

27
Q

Dynamic range describes what?

A

the number of grays available for imaging

28
Q

What changes the dynamic range?

A

Compression

29
Q

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

A

wide, low, plaque

30
Q

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

A

narrow, high, vein compressions

31
Q

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

A

twice

32
Q

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

A

4 MHz

33
Q

The best use of harmonic imaging is in ___________.

A

Deeper structures

34
Q

Strength of the harmonic wave ___________ as sound travels.

A

increases

35
Q

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

A

contrast agents, create stronger reflectors

36
Q

Microbubbles are used to see ___________ better in small spaces

A

blood flow

37
Q

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

A

non-linear, grow and shrink when hit with soundwaves

38
Q

Low _______ and high _________ will increase harmonics.

A

frequency, amplitude

39
Q

The mechanical index estimates the amount of what?

A

harmonics created

40
Q

What is a common, short-lived contrast agent?

A

Agitated Saline