# Test 2 Flashcards Preview

## Physics II > Test 2 > Flashcards

Flashcards in Test 2 Deck (80)
1
Q

What are the 3 variables of the range equation?

A
• Time
• Distance
• Speed
2
Q

What is the time from a pulse being sent to a pulse being recieved called?

A

Time of flight.

3
Q

When is time of flight short? in superficial or deep structures?

A

Superfical.

4
Q

The time-of-flight is directly related to what?

A

Depth.

5
Q

What is the range equation?

A

Depth (mm)=(1.54 mm/usec x time-of-flight (us))/2

6
Q

For every 13us of time-of-flight, the object creating the reflection is how much deeper?

A

1cm

7
Q

What is the reflectors depth if a pulses time-of-flight is 26 us?

A

2 cm deep.

8
Q

How do you find period?

A

1/f

9
Q

How do you find the frequency?

A

1/t

10
Q

What is PRP?

A

It is the time from the start of one pulse to the start of the next pulse.

11
Q

When the depth of view is shallow, what type of PRP would it have?

A

Short.

12
Q

When the depth of view is deep, what does it PRP look like?

A

Long.

13
Q

What is the equation for PRP?

A

PRP=imaging depth (cm) x 13us/cm

14
Q

What is PRP directly related to?

A

Maximum imaging depth.

15
Q

When the depth of view is shallow, how is the PRF?

A

High.

16
Q

When the depth of view is deep, PRF is like?

A

Low.

17
Q

What is the equation for PRF?

A

PRF (Hz)= 77,000 cm/s/image depth (cm)

18
Q

PRF is inversely related to what?

A

Imaging depth.

19
Q

What is “duty factor”?

A

It counts how long a pulse is on duty.

20
Q

What is the equation of Duty Factor?

A

DF %=(Pulse duration/PRP) x 100

21
Q

What are the advantages of a Pencil probe/Pedof probe?

A
• Sensitive
• Inexpensive
• Inexpensive electronics necessary
22
Q

What are the disadvantages of the Pencil probe/Pedof probe?

A
• No image
• Manual steering
• Fixed focus for transmiting and receiving.
23
Q

Describe a Mechanical transducer: single element

A
• First generation (static scanners)
• Mechanical steering-single element.
24
Q

What are the advantages to a mechanical transducer: single element?

A
• 2D image
• Wide field
25
Q

What are the disadvantages to a Mechanical transucer: single element?

A
• No steering
• Fixed transmitig and recieving focus.
• Parts wear out/break,
• Motion artifacts
26
Q

What are the advantages to a Mechanical transducer: Annular array?

A
• 2D
• Variable focus (lateral, elevation)
• Wide field
27
Q

What are the disavantages to a Mechanical transducer: Annular array?

A
• Motion artifact
• Parts wear out
• Limited temporal resolution
28
Q

What are the advantages of a Linear Switched Array?

A
• 2D
• Electronic switches
• Wide field.
29
Q

What are the disadvantages of the Linear Switched Array?

A
• No steering
• Fixed focus (lateral, elevation)
30
Q

What is the Linear Phased Array associated with?

A

Hugen’s principle.

31
Q

What are the advantages of the Linear Phased Array?

A
• 2D image
• Electronic pulsed sequencing
• Variable focus (lateral)
• Steering.
32
Q

What are the disadvantages of the Linear Phased Array?

A
• Expensive
• Fixed focus (elevation)
33
Q

What are the advantages of the Sector Phased Array?

A
• Viable focus in lateral
• Has a small footprint which aids in intercostal access.
• 2D
34
Q

What are the disadvantages to a Sector Phased Array?

A
• Fixed elevation focus
• Expensive
• No steering in elevation direction.
35
Q

What are 4 other types of transducers?

A
1. Transesophogeal
2. transrectal
3. Intravascular
4. Waterpath-standoff
36
Q

What 4 things can cause damage to transducers?

A
1. Heat
2. Dropping
3. Delamination
4. Cable damage
37
Q

How does heat damage the transducers?

A

It causes:

• Depolarization
38
Q

How does dropping damage the transucer?

A

It causes:

• Cracking case
• Electrical exposure
• Loss of probe sensitivity
39
Q

How does delamination damage the transducer?

A

It causes:

• Caustic solvents
• Loss of probe sensitivity
40
Q

How does cable damage, damage the transducer?

A

It causes:

• Loss of probe sensitivity.
41
Q

What is frame rate also known as?

A

Frame frequency.

42
Q

What is the time it takes to shoot one image called?

A

“frame time”

43
Q

What is the equation for Frame Rate?

A

FR=1/FT

44
Q

What is the equation for line time?

A

LT=13us/cm x depth cm

45
Q

What is the equation for frame time?

A

FT= Line time x # of lines.

46
Q

What does color add to frame time?

A

47
Q

What is the equation for packet time?

A

PT=( Line time x # lines repeated )/packet.

48
Q

What happens to the frame frequency and temporal resolution if the frame time increases?

A

They both decreases.

49
Q

What are 3 ways to impove frame rate?

A
1. Decrease depth
2. Turn off color
3. Decrease width of color box.
50
Q

What does decreasing the width of the color box do?

A

It reduces amount of times a packet has to shoot.

51
Q

What does the transmitter/pulser do?

A

It turns electropotential energy into PZT then into pressure and vice versa.

52
Q

What does the transmitter/pulser sensitivity aid it?

A

Detecting the weakest signal.

53
Q

Increased power transmitted and intensity results in?

A

Improved sensitivity.

54
Q

What happens if you increase the power?

A

It increases exposure to patient.

55
Q

What is power porpotional to?

A
• Intensity
• Amplitude (brightness)
56
Q

Gain is _____

A

Power.

57
Q

What is the equation for gain?

A

Gain=20 Log Amax/Amin

58
Q

What is the “signal-to-noise” ratio?

A

It is a comparison of meaningful information (signal) in an image, compared to the amount of contamination (noise).

59
Q

When is the signal much stronger than the noise AND the image is of high quality?

A

When the signal-to-noise ratio is high.

60
Q

When is the signal strength closer to the the strength of noise? The image will contain a larger amount of visible contamination.

A

When the signal-to-noise ratio is low.

61
Q

What does increased power do to the signal-to-noise ratio?

A

It increases the signal-to-noise ratio.

62
Q

What does the beam former do?

A
• It creates appropriate phase delays to transmitted signal.
• Applies appropriate phase delays to recieved signal.
63
Q

What are 3 characteristics of a beam former?

A
1. Stable
2. Programmable
3. Accepts large bandwidth
64
Q

What is apodization?

A

It is when the beam former adjust electrical spike voltages to reduce lobe artifacts.

65
Q

What does apodization do to lobes?

A

It decreases lobes.

66
Q

What is the most important thing to remember of a reciever?

A

Reciever functions do not affect exposure to patients.

67
Q

What are the 5 functions of the reciever?

A
1. Amplification
2. Compensation
3. Compression
4. Demodulation
5. Rejection
68
Q

What does a recievers amplification do?

A
• It raises strength of attenuated reflections
• Strength increases equally for all reflections
69
Q

What does a recievers compensation do?

A
• It corrects for attenuation as depth increases
70
Q

What is a function that can be used for compensation?

A
1. TGC
2. DGC
3. TDC
71
Q

What does a recievers compression do?

A
• It maintains “relative” difference in reflection.
• Considers limitations of viewer (shades of grey)
72
Q

What does a recievers demodulation do ?

A
• It changes signal into suitable form for monitor
• Rectification→Flips
• Smoothing→Simplifies the echo
73
Q

What does a recievers reject do?

A
• Removes :
• Low-level reflections
• Non-meaningful information/noise
74
Q

What are 6 different types of imagining modes?

A
1. A-Mode
2. B-Mode
3. C-Mode
4. M-Mode
5. Real-time
6. Grey scale
75
Q

What is A-Mode?

A
• Amplitude
• it is mainly used in opthamology.
76
Q

What is M-Mode?

A
• Motion
• Used in echo.
77
Q

What is C-Mode?

A
• Constant
• Doppler and color.
78
Q

What is the equation for dynamic range?

A

dB=20 Log10Amax/Amin

79
Q

How many dB is in US?

A

100

80
Q

How many dB in the human eye?

A