Exam 4 Flashcards
1
Q
Ability to detect and display echo amplitude differences
A
Contrast resolution
2
Q
Better contrast resolution allows for differentiation of echoes that are
A
Very close together in amplitude to be shown as different SOG
3
Q
What is the gold standard for resolution
A
Ability to display fetal lip echoes at different SOG than fetal cheek echo
4
Q
What is the equation of contrast resolution
A
Dynamic range/SOG
5
Q
What are the units of contract resolution
A
dB/SOG
6
Q
Contrast resolution is determined by
A
Dynamic range and number of SOG it can store/display
7
Q
When echoes are further apart in amplitude and intensity they’re displayed as
A
Different shades
8
Q
Poor resolution echoes are ____ (Far or close) and are the same _____
A
Close and are same SOG
9
Q
Range of signals that a piece of equipment is processing
A
Dynamic Range
10
Q
The minimum dynamic range is detected by
A
Piece of equipment
11
Q
The maximum dynamic range can be
A
Processed without distoration
12
Q
What are the units of dynamic range
A
dB
13
Q
What is the equation for Nyquist criteria
A
PRF/2
14
Q
Analog numbers have _____ & _____ values
A
Unlimited and continuous
15
Q
What was the first type of scan converter
A
Analog
16
Q
Analog converted has good spatial resolution because of
A
Continous values being read and displayed
17
Q
What are the disadvantages of analog scan converter
A
Instability
Image flicker
Deterioration
Image fade
18
Q
What causes the instability in analog scan converter
A
Image is influenced by other factors such as room temp
19
Q
What causes the image flicker in analog scan converter
A
Constant need to read and write new info
20
Q
What causes the deterioration in analog scan converter
A
The older the image the more the image degrades
21
Q
What causes the image fade in analog scan converter
A
Electron charges dissipated and image becomes darker over time
22
Q
Digital numbers have _____ & _____ values
A
Distinct & Discrete Values
23
Q
T or F:
Digital numbers sample and store only some values
A
True
24
Q
What are the advantages of digital scan converter
A
Durability
Uniformity
Stability
Accuracy
25
What causes the durability for the digital scan converter
Quality of image doesn't deteriorate with age/heavy use
26
What causes the uniformity for the digital scan converter
Image has consistent grayscale throughout
27
What causes the stability for the digital scan converter
Image doesn't fade or drift
28
What causes the accuracy for the digital scan converter
Image is error free
29
T or F:
Convert D to A first
False
Convert A to D
30
Smallest part of digital picture that can be controlled
Pixel
31
Pixel is denisty per
Inch
32
High pixel density improves ____ ____ and results in an image with _____ (Good or poor) detail
Spatial resolution, better detail
33
How many bits are in 1 byte
8
34
Magnification is used to
Improve visualization f ROI
35
Performed while data is being read in, before storage in the scan converter
Write magnification
36
What are the 4 steps for write magnification
Scan
Convert A to D
Identify ROI & system discards data
U/S system rescans ROI & write new data
37
Finish the characteristics of write magnification:
Used to -
Number of pixels in ROI -
Increased number of pixels in -
Identify ROI discarded
Greater than ROI of original image
ROI improves spatial resolution
38
Performed after image is stored in scan converter
Read magnification
39
What are the 3 steps for read magnification
Scan
Convert A to D, store data
Select ROI, system reads & displays only that info
40
Finish the characteristics of read magnification:
Number of pixels in magnified image -
Spatial resolution -
Can be done -
Same as in original
Does not change
On frozen image
41
What is Bernoulli's equation
P + 1/2pv^2 + pgh
42
What does P stand for in Bernoulli's equation and what are it's units
Pressure
Pascals
43
What does p stand for in Bernoulli's equation and what is the equation for it
Density
Mass/volume
44
What does v stand for in Bernoulli's equation
Velocity
45
What does 1/2pv^2 stand for in Bernoulli's equation
Kinetic energy
46
What does pgh stand for and when is it cut out
Potential energy
Cut out in stenosis
47
What does capacitance look at
Change in volume
48
What is the equation for capacitance
Change in volume/Change in time
49
What is the equation for compliance
Change in volume/Change in pressure
50
The greek letter n or ____ is used to represent _____
Aeta
Viscosity
51
Define viscosity
Resistence to flow
52
What is the resistance expression
R = 8nl/pie x r^4
53
What is RN
Reynolds number
54
What does the Reynolds number 2,000 or 3,000 indicate
Turbulence
55
In a series you will have a larger
Final sum
56
In parallel you will always have a smaller
Final sum
57
Is pressure higher in your legs than in your arm?
Yes
58
CRT stands for
Also known as
Cathode Ray Tube
Electron gun
59
CRT's important component is the
Anode/focusing coil
60
What do focusing coils do
Eliminate stray electrons
61
Sweeping coils are ____ that do what to the electron beam
Magents that move electron beam to different regions across the screen
62
Draw the CRT diagram
Electron gun
Focusing coil
Sweeping coil
Electron beam
Phosphorus
63
RGB used to produce
All colors of rainbow
64
Substance that glows when activated by electron gun
Phosphorus
65
Define rastering
Sweeping of the beam across the display
66
What are the 4 characteristics of imaging
Normal incidence
High f improves resolution
PW only
Min 1 crystal
67
What are the characteristics of Doppler
0-180
Low f, avoid aliasing
PW & CW
Min of 1 for PW, 2 for CW
68
What does BART represent
Blue away, red towards
69
CW has the ____ (Highest or Lowest) velocity anywhere along ____ of beam
Highest
Length
70
What are the 4 characteristics of CW Doppler:
R
M
G
N
Range ambiguity
Most sensitive
Good temporal resolution
No aliasing
71
Why does CW Doppler have 2 elements
Transmitting always busy so necessary to have one for receiving
72
CW Doppler is produced by continuous application of
Alternating electrical current
73
CW Doppler is determined by
Frequency of alternating current
74
CW alternates current by
Flipping positive and negative charge
75
PW Doppler is good on
Location of flow
76
What are 4 characteristics of PW Doppler:
R
M
G
A
Range resolution
Moderate sensitivity
Good temporal resolution
Aliasing
77
What do CW and PW Doppler measure
Peak velocity
78
What is on the X-Axis and Y-Axis for PW Doppler
X-Axis - Time
Y-Axis - Frequency/Velocity
79
PW is produced by short
Repeated pulses with pauses between
80
Where are the positive and negative shifts shown on PW Doppler
Positive is above baseline
Negative is below baseline
81
What are the 3 ways of increasing aliasing
Faster blood flow velocity
High f transducer
Deeper gates/Low PRF
82
What are the 5 ways to clean up aliasing
Adjust max scale
Select new window with shallow simple volume
Use low f transducer
Use baseline shift
Use CW Doppler
83
How does adjusting max scale affect Nyquist limit
Increase
84
How does selecting a new window with shallow simple volume affect Nyquist limit
Increase
85
How does using low f transducer affect Doppler shift
Decrease
86
How does using baseline shift affect display
Display looks better
87
Using CW Doppler may avoid ____ but then you deal with ____ ____
Aliasing
Range ambiguity
88
With deep Doppler smaple gate and high velocity flow operator must choose between
Aliasing and range ambiguity
89
Deep ultrasound reflectors requires ____ (Long or Short) PRP and ____ (High or Low) PRF
Long, low
90
High velocity blood has high Doppler shifts requires ____ (high or low) PRF to avoid ____
High PRF
Avoid aliasing
91
Info from number of pulses required to estimate velocity of blood flow
Pulse packet
92
I iii I iii I
The i's represent
Echoes going and returning
93
Which return first shallow or deep
Shallow
94
The heart has __mm of mercury
0
95
What is the equation of continuity
Q = avg velocity x area
96
If you have a narrow region how does that affect your velocity
Faster velocity
97
If you have high velocity you will have a ____ (Small or big) area
Small
98
What are the 4 devices used for storage
Paper
Magnetic Media
Chemical Derived Photos
Optical media
99
What are the 5 order of receiver operations
Amplitfication
Compensation
Compression
Demodulation
Reject
100
What is the equation for parallel series
1/Reffective = 1/R1 + 1/R2
101
What does amplification do
Each signal returning from trip is larger
102
What does compensation do
Correct for attenuation
103
What does compression do
Keeps grayscale in content in regions of viewable shades
104
What does demodulation do
Electrical signal from receiver is made into suitable image
105
What does reject do
Suppresses spurious signals
106
How much is 1 byte of info
2^8 (256)
107
If you increase your length how will that affect your resistence
Increase
108
If you decrease your viscosity how will that affect your resistance
Increase
109
If your radius decreases how will that affect your resistance
Increase (To the 4th power)
110
If you radius is decrease of 1/16 then your resistence will be
Increase by 16
111
Blood flow is due to change in
Pressure
112
In CRT which do you sweep first, odds or evens?
Odds
113
If you have 0 compliance what will it do
Not change anything
114
Finite can increase
Volume
115
T or F:
Infinite does exist
False
Doesn't exist
116
What is the Hemo Law Equation
Change in pressure = Q (fluid flow) x Resistance
117
If you have a fixed change in pressure and your fluid flow (Q) is increased how will that affect your resistance
Decrease
