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1
Q

What are the advantages of backing material?

A

Improves axial resolution
Shortens pulse length
Increase bandwidth
Decrease Q factor

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2
Q

Frequency is determined by

A

Thickness of crystal

Prop speed of crystal

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3
Q

Spatial resolution consists of

A

Longitudinal and Lateral resolution

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4
Q

What is longitudinal resolution?

A

Distinguish two structures that are close to each other parallel to the sound beam
•-•. •-•

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5
Q

Longitudinal resolution is improved by?

A

Increased damping material (less ringing)
Higher frequency (shorter pulse)
Shorter wavelength

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6
Q

The longitudinal resolution value ranges from?

A

0.05 to 0.5 mm

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7
Q

What is lateral resolution?

A

Minimum distance that two structures are separated by side-to-side that produce two distinct echos

•
|
•

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8
Q

Lateral resolution is best at the?

A

Near zone length

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9
Q

What improves lateral resolution?

A

Focusing

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10
Q

What is temporal resolution?

A

Read resolution pertaining to time

It is the time spent to make a frame

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11
Q

What is frame rate?

A

The number of frames ultrasound machine displays in one second

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12
Q

Frame rate is good for what type of resolution?

A

Temporal resolution

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13
Q

As temporal resolution increases image quality what resolution decreases?

A

Spatial resolution

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14
Q

If less time is needed to create an image the frame rate will?
While temporal resolution?

A

Increase

Improves

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15
Q

What improves temporal resolution?

A

Single focus transducer
Less depth of penetration
Narrow sector angle
Less line density (less scan line)

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16
Q

Gain is a ratio of

A

Output and input electrical power

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17
Q

What is contrast resolution?

A

Described as ability to distinguish between slightly different shades of gray

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18
Q

Dynamic range is also known as

A

Compression

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19
Q

What is dynamic range?

A

Ratio in dB from largest to smallest power that a system can handle

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20
Q

A wide dynamic range displays more?

A

Shades of gray

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21
Q

A narrow dynamic range results in more

A

Black and white appearance of the image

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22
Q

What is bandwidth?

A

A range of frequencies below and above the main frequency.

it is the difference between the highest and lowest frequency emitted from transducer

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23
Q

A wide bandwidth is created from a

A

Short pulse

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24
Q

A short pulse is created by the use of more

A

Damping material

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25
The damping process on transducer
Decreases PD Decreases SPL Shorter pulses produce less ringing
26
What is quality factor?
Unitless number that represents the degree of damping
27
What is the formula for Q factor?
Q= operating frequency/ BW
28
What is specular reflection?
Very smooth Flat boundary Wavelength is larger compared to the boundary roughness Create grayscale image artifact called mirror
29
What is non specular or diffuse scattering?
Very rough Irregular borders When wavelength is smaller compared to the boundary roughness
30
In soft tissue the depth of penetration decreases when
Frequency increases | Attenuation coefficient increases
31
Half layer thickness depends on the
Frequency of sound | Medium through which a sound is propagating
32
What is impedance?
Is the acoustic resistance a countered when sound travels propagates through the medium
33
What is the formula for impedance?
Z= p x c
34
What is incidence?
Angle between incidence and direction in a line perpendicular to or oblique to the boundary of the medium
35
What is perpendicular incidence?
Boundaries between media with and different impedance has part of the sound is reflected in part is transmitted
36
Incident intensity is?
Intensity that the sound wave has before it hits a boundary
37
What is reflected intensity?
Remains after hitting the boundary and a second return back in the same direction that it came from
38
What is transmitted intensity?
Intensity that continues the path after striking the boundary through the second medium
39
Oblique incidence is?
Not at right angle | Not 90 degrees
40
Reflection can only be calculated with
Normal incidence | Different impedances
41
Refraction occurs with
Oblique incidences | Different prop speeds
42
Transmission occurs with
Normal or oblique incidence
43
What is specular reflection?
Two media are smooth | Wavelength is small compared to the boundary dimension
44
What is speckle artifact?
Displayed dot that does not represent scatters
45
What is persistence button?
Average has consecutive frames for produces a smoother image
46
What is Fast Fourier Transform?
Range if velocities found in beam
47
When does aliasing occur?
When Doppler shift exceeds the Nyquist limit which is one half of PRF
48
How to correct aliasing?
``` Decrease the baseline Increase scale Increase Doppler effort (angle) Increase the frequency Switch to cw ```
49
What does color Doppler imaging or color flow image use?
``` Determines presence of flow Direction of flow Type of vessel Flow characteristic (laminar, turbulent) Absence of flow (testicular torsion) Increase perfusion (possible malignancy) Determine if it is a cystic structure or vessel ```
50
Color power doppler or ultrasound angio or color Doppler energy or color power angio is?
Color flow display according to strength. | Free of aliasing, not angle dependent, high sensitivity to flow in small vessels
51
What is color Doppler?
Pulsed wave Changing color means velocity change or aliasing Information about velocities Velocities converted into color
52
What is color bar?
Color used to describe flow velocity
53
Where is the color bar located?
Upper left side of screen
54
The higher the position of color on the bar
Greater velocity flow of RBC toward transducer
55
The lower the position of color on the bar
Greater velocity away from the transducer
56
What are the two types of modes on the color bar?
Velocity mode | Variant mode
57
What is velocity mode?
Multiple velocity such as red, black, blue
58
What is variance mode?
Measure spectral (color)
59
In color Doppler absence of green means?
Velocities are the same
60
In color Doppler the presence of green means?
Change in velocity or presence of turbulence
61
What is color flow processing?
Velocity detection for color Doppler
62
What is auto correction?
Obtaining mean Doppler shift frequency
63
Package size is also known as?
Ensamble length
64
What is packet size?
Group of pulses Number of pulses per color line Compose of 3 to 20 pulses
65
The larger the package size
Lower the frame rate
66
When a packet has more pulses, the following results occur?
Velocity measurement more accurate More time required to collect data from each scan line which degrades temporal resolution More poses are needed to make a single frame
67
What is hemodynamics?
Study of motion and the force of blood
68
The human circulatory system consists of?
``` Heart Arteries Arterioles Capillaries Venules Veins ```
69
How many liters of blood is in the circulatory system?
5 L
70
What is stroke volume?
Volume of blood that is ejected by the left ventricle into aorta. Each heartbeat equals to 75 to 80 ml
71
Blood consists of
Plasma 90% water 10% protein RBC 90% cells contain hemoglobin WBC protect body Platelets smaller blood cell, helps in blood clotting
72
What are the two important characteristics of blood?
Density | Viscosity
73
What is density?
Equal to Mass per unit of volume
74
What is the formula for density?
D=M/V
75
What is viscosity?
Resistance to blood in motion
76
Viscosities unit is
Poise
77
Viscosity blood is about?
0.035 poise
78
What is pulsatile flow?
Normal in arterial circulatory system
79
what is plug flow?
Entrance of the vessel, blood travels at the same speed at the center or next to the blood vessel wall at distance, plug flow changes to parabolic flow
80
What is laminar flow?
Particles are parallel to each other and the highest velocity of blood flow is in the center of the vessels slowing by the wall of vessel
81
What is parabolic flow?
Develop in a long vessel with steady flow | It is a laminar flow with parabolic cone shape
82
What is Disturbed flow?
Not steady flow Occurs after bifurcation Narrowing of the vessel stenosis or in the small vessel
83
What is turbulent flow?
Occurs when Reynold's number exceeds 2000 | Baker's ad vessel bifurcation or stenosis
84
Blood flow occurs between differences in
Energy and pressure which is called gradients
85
Blood pressure is higher in the legs when standing or when sitting down
In the legs
86
What is pressure gradient?
blood flow to occur between any two points in the circulatory system there has to be different than the energy level pressure between the two points
87
What are the two types of pressures the circulatory system consists of?
``` High pressure (Arterial) Low pressure (venous) ```
88
What are the two systems that are connected by a micro circulation?
Capillaries | Resistance vessels
89
Both pressure and energy increase or decrease when blood moves from the arterial system to the venous system
Decrease
90
CWD measures anywhere along the length of the beam which is called?
Range ambiguity
91
PWD selects sample called
Range Resolution
92
CWD measures what type of velocity?
High velocity | Above 2.0 m/s
93
PWD measures
Low velocity | Below 2.0 m/s
94
Aliasing occurs in CWD or PWD
PWD
95
Why can't CWD have aliasing?
Cannot measure high velocity accurately. No PRF
96
PWD has how many crystals?
1 sending and receiving
97
CWD has how many crystals?
2 only receiving
98
What is heart?
4 Chambers . Engine of system
99
What are arteries?
Main conduit. Media consists of elastin
100
What are arterioles?
Mostly muscular tissue on the wall and is responsible for 68% of the lower extremity (peripheral resistance)
101
What part of the circulatory system have the highest resistance to blood flow?
Arterioles Venules Capillaries
102
What are capillaries?
Found by only one layer of cells. | Brings nutrients and oxygen to the cells
103
What is venules?
Take cell waste products and deoxygenated blood from
104
What are veins?
Low resistance, Low fow and low pressure vessels Reservoir of the circulatory system

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