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LMC Ultrasound > PHY 2 FINAL > Flashcards

PHY 2 FINAL Flashcards

1
Q

What is the frequency of a transducer if the period is 25 million cycles/ sec?

A

25 MHz Pg. 21

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2
Q

What are the ranges for audible, ultrasound, and infrasound?

A

Infrasound - less than 20Hz Audible - 20Hz - 20 kHz Ultrasound - greater than 20kHz Pg. 22

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3
Q

What are the seven parameters to describe sound waves? Is it adjustable? What is is determined by?

A

Period (time)- not adjustable, determined by source
Frequency (Hz)- not adjustable, determined by source
Amplitude (dB)- adjustable, determined by source
Power (W)- adjustable, determined by source
Intensity (W/cm2)- adjustable, determined by source
Wavelength (distance)- not adjustable, determined by source and medium
Speed (m/s)- not adjustable, determined by medium

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4
Q

If intensity remains the same, while power is doubled, what happens to the beam area?

A

Doubled Pg 44

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5
Q

What are the acoustic variables?

A

Pressure (pascals)
Density (kg/cm^3)
Distance (cm,mm) Pg 12

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6
Q

What would create the longest wavelength?

A

The lower the frequency, the longer the wavelength pg. 34

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7
Q

What is the term used to describe from the start of a pulse to the end of a pulse?

A

Pulse duration Pg 49

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8
Q

What scale do we use for decibels?

A

Logarithmic Pg 77

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9
Q

What will intensity do if you have 3 dBs?

A

Intensity is doubled at 3dB Pg 78

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10
Q

If initial intensity is less than the final intensity, then what will the gain in decibels be?

A

Positive, the beam’s intensity is increasing pg. 79

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11
Q

Rayleigh scattering is related to ___.

A

Frequency^4

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12
Q

Soft tissue attenuation coefficient is directly related to ___.

A

Frequency Attenuation coefficient= 0.5dB/cm/MHz

pg. 85

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13
Q

What are the different speeds and attenuation we will find in different mediums?

A

Medium, Attenuation, speed water, extremely low, 1480m/s blood/urine/biological fluids, low, 1560m/s fat, low 1450m/s soft tissue, intermediate 1540m/s muscle, higher, 1600m/s bong and lung, even higher, 3500m/s (bone) 500m/s (lung) air, extremely high, 300m/s pg. 86 and 37

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14
Q

If two PZT are made from the same material, the thicker crystal will make a pulsed transducer that is ___.

A

Lower frequency pg. 127

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15
Q

What happens when we exceed the Curie point?

A

Depolarization Pg 120

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16
Q

Which component of a transducer reduces ringing of a pulse and is made of epoxy resin impregnated with tungsten filaments?

A

Backing material “Damping element” Pg 115

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17
Q

Know all about crystals and what they may produce (thick/thin crystals, high/low speeds).

A

Materials which convert sound into electricity and vice versa
Names: Piezoelectric, ferroelectric, PZT, lead zirconate titanate, ceramic, active element, & crystal
High frequency transducer: thinner PZT with higher speeds
Low frequency transducer: thicker PZT with lower speeds
pg. 113 & 125

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18
Q

What resolution is improved by damping material?

A

Axial Pg 115

Longitudinal pg. 126

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19
Q

The voltage of a pulsed transducer is 6 MHz, what will the frequency be?

A

Cannot be determined by electrical signal pg. 126

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20
Q

Frequency is given for a continuous wave probe is 6 MHz, what is the operating frequency? (what is the relationship between these two)

A

Identical (6MHz) pg. 127

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21
Q

What is the order of impedences from greatest to least? (matching layer, skin, gel, PZT)

A

PZT > matching layer > gel > skin pg. 116

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22
Q

Which component of a transducer contains cork and prevents vibrations in the case from inducing an electrical voltage in the PZT of the transducer?

A

Acoustic insulator Pg 115

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23
Q

What does the matching layer do?

A

Increases the percentage of transmitted sound between the active element and the skin; protects the active element pg. 115-116

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24
Q

How are frequency and near zone length related?

A

Directly Pg 135

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25
Q

Anatomy of a sound wave (5 questions)

A
  • Focus/focal point= where the beam is narrowest
  • Near Zone/field, Fresnel Zone= distance from the transducer to the focus
  • Near zone length/focal zone length/ focal depth= distance from the transducer face to the focus
  • Far zone/ field, Fraunhoffer zone= region deeper than the focus, where the sound beam diverges
  • Focal zone= region around the focus where the beam is relatively narrow, where the most accurate images come from
    pg. 131
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26
Q

How is the focal length of a sound beam determined?

A

1) Transducer diameter
2) Frequency of sound
pg. 135

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27
Q

What is the spread of a sound beam in the far field?

A

Divergence pg. 139

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28
Q

What will create the best lateral resolution in the far field based on frequency and diameter?

A

The largest diameter and highest frequency (least divergence)
pg. 153

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29
Q

LARRD (multiple questions)

A 
Longitudinal 
Axial 
Range 
Radial 
Depth 
-parallel to beam's axis 
-best with less ringing and high frequency pg. 146
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30
Q

LATA (multiple questions)

A 
Lateral 
Angular 
Transverse 
Azimuthal 
- perpendicular to beam's axis 
- best with decrease FOV and at focus 
pg. 153
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31
Q

What is lateral resolution?

A

the ability to distinguish 2 structures perpendicular to beam
pg. 151

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32
Q

Which intensity is most important when it comes to biological effects?

A

SPTA pg. 74

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33
Q

Which intensity is considered the maximum?

A

Peak Pg 69

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34
Q

What are the units for intensity?

A

W/cm^2 pg. 73

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35
Q

What are the six different kinds of intensity?

A 
SPTP
SATP
SPTA
SATA
SPPA
SAPA
p73
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36
Q

What is an incident of a sound wave?

A

The angle at which the wave strikes the boundary

p90

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37
Q

What is the difference between transmission, reflection, and incident intensity? (6 questions)

A

Incident intensity= the sound wave’s intensity immediately before it strikes a boundary
Reflected intensity= percentage of intensity that returns , after striking the boundary
Transmitted intensity=the percentage of intensity that continues forward after the boundary

Incident intensity= reflected intensity + transmitted intensity

pg 92

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38
Q

What is the half value layer thickness?

A

The distance sound travels in a tissue that reduces the intensity of sound to 1/2 of its original value. pg 87

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39
Q

What is the angle degree for normal incidence?

A

90

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40
Q

What is the intensity reflection coefficient? (3 questions)

A

The percentage of the intensity that bounces back when a sound beam strikes the boundary between 2 media.
In clinical imaging, very little of the sound wave’s intensity is reflected at the boundary between 2 soft tissues.
Greater percentage of the wave is reflected when it strikes a boundary between soft tissue and bode or air. pg 93

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41
Q

To have normal incidence, you have to have different what?

A

difference in acoustic impedance. pg 88

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42
Q

Specular reflections arise from what?

A

The sound is reflected in only one direction in an organized manner. When it strikes a smooth boundary. pg 81

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43
Q

What is the term used to describe transmission with a bend?

A

Refraction pg 100

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44
Q

What can happen with both oblique incidence and different propagation speeds?

A

Refraction pg 101

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45
Q

Snell’s Law describes what?

A

The physics of refraction pg. 102

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46
Q

What is it called when two sound waves are traveling towards something and they both arrive at the same time?

A

Interference Pg 18

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47
Q

Thumbs up and thumbs down rule (stiffness and density)

A

Stiffness directly related to speed
Density inversely related to speed
pg. 39
Stiff but not dense will have the fastest speed
Not stiff and very dense will have the slowest speed

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48
Q

What is attenuation?

A

Sound waves weaken as they propagate in a medium. A decrease in intensity, power and amplitude as the sound travels through the medium
pg 80

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49
Q

Impedence is a characteristic of what?

A

Medium only pg 88

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50
Q

What type of transducer and frequency do we use on different parts of the body?

A

Small parts: Linear, High frequency Abdomen: Convex, Lower frequency

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51
Q

What is the ability to distinguish between two structures lying close together called?

A

Resolution pg. 149

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52
Q

What is the best choice for attenuation coefficient in soft tissue?

A

one-half of the frequency pg 85

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53
Q

Attenuation is determined by what two factors?

A

1.path length
2.frequency
pg 80

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54
Q

What is the term used to describe the redirection of sound in many directions?

A

Scattering pg 82

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55
Q

What do we consider a rough boundary?

A

most interfaces in the body pg. 82

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56
Q

What is time of flight?

A

The elapsed time from pulse creation to pulse reception

pg. 107

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57
Q

What is Q-factor?

A

Q-factor = main frequency/bandwidth Imaging probes have a low-Q pg. 119

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58
Q

All the different names used to describe time of flight

A

Go return time pg. 107

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59
Q

What is the 13 microsecond rule?

A

When sound travels through soft tissue, for every 13 microseconds of go-return time, the object creating the reflection is 1 cm deeper pg. 108

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60
Q

When you change your depth, what happens to PRP?

A

Doubles Per Game Review
Shallow Depth = Short PRP
pg. 109

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61
Q

Axial resolution deals with structures that are located where on the sound beam?

A

Parallel Per Game Review pg. 145

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62
Q

What happens to the numerical value of LARRD as frequency increases?

A

Decreases Per Game Review pg. 148

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63
Q

If you are given a frequency, what will have the best axial resolution? # of cycles

A

High frequency (shorter wavelength)
Fewer cycles per pulse (less ringing)
pg. 148

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64
Q

Why is it difficult to study biological effects in living tissue?

A

Absorption (biggest reason), scattering and reflection pg. 170

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65
Q

What is the empirical approach?

A

Based on the acquisition and review of information from patients and animals exposed to ultrasound. Searches for a relationship between exposure and response pg. 407

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66
Q

What is the difference between stable cavitation and transient cavitation?

A

Stable:
oscillating
bubble microstreamng and shear stresses
lower MI

Transient:
normal, inertial 
bursting bubble 
shock waves and very high temperatures 
higher MI pg. 411
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67
Q

What is the primary investigative technique used in epidemiology?

A

Reviewing of the charts Per Game Review

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68
Q

What is the most common intensity that is involved with tissue heating?

A

SPTA pg. 74

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69
Q

How do we study biological effects of non-living things?

A

in vitro pg. 405

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70
Q

Which will have the least amount of temperature elevation, focused or unfocused sound beams?

A

Focused sound beams per Game Review

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71
Q

What should we do if we find a broken housing or a frayed wire on an ultrasound machine?

A

Do not use it

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72
Q

When is it okay to perform an ultrasound on a patient?

A

When the benefits outweigh the risks pg. 405

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73
Q

What is the x-axis and y-axis on A, B, and M Mode?

A

A-mode: x=depth, y=amplitude z=none
B-mode: x=depth, y=none, z=amplitude
M-mode: x=time, y=depth, z=none
pg. 163

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74
Q

A Mode

A

Amplitude Mode appearing as a series of upward spikes (big city skyline) pg. 159-160

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75
Q

B Mode

A

Brightness Mode appearing as a line of dots of varying brightness, first form of gray scale imaging pg. 161

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76
Q

M Mode

A

Motion Mode appearing as a group of horizontal wavy lines (heart rate) pg. 162
Only one that provides information about a reflector’s changing location with respect to time

77
Q

What must we have to have gray scale imaging?

A

scan converter Per Game Review

78
Q

What is the difference between pre-processing and post-processing?

A

Pre-processing is manipulation of image data before storage
Post-processing is manipulation of image data after stoarge
pg. 249

79
Q

What is spatial compouding?

A

method of using sonographic information from several different imaging angles to produce 1 single image pg. 254

80
Q

What is fill-in interpolation?

A

method of constructing new simulated data points to fill in the gaps pg. 257

81
Q

What is persistence?

A

AKA temporal compounding or averaging image processing technique that continues to display information from older images, which smooths the image pg. 256

82
Q

What is edge enhancement?

A

image processing method that makes pictures look sharper pg. 255

83
Q

What are the advantages of the PACS system?

A

virtually instant access to archived studies
no degradation of data ability to electronically transmit images and reports to remote sites
“store and forward”
pg. 259

84
Q

When sending the signal from the transducer to the receiver, what form is the information in?

A

analog to digital form pg. 247

85
Q

What do contrast agents need to be?

A 
Safe 
Metabolically inert 
Long lasting 
Strong reflector of ultrasound 
Small enough to pass through capillaries 
pg. 278
86
Q

What is harmonic imaging? (convert harmonic frequency to fundamental frequency)

A

harmonic imaging is the creatioin of an image from sound reflections at twice the frequency of the transmitted sound pg. 269

87
Q

What is the difference between pulsatile and phasic flow?

A

Pulsatile flow occurs when blood moves with a variable velocity. (cardiac contraction, arterial)
Phasic flow occurs when blood moves with a variable velocity (respiration, venous) pg. 286

88
Q

What are the different types of laminar flow?

A

Plug flow: all layers and blood cells travel at the same velocity
Parabolic flow: flow has bullet-shaped profile pg. 287

89
Q

What is the Reynold’s number for turbulent flow?

A

greater than 2000 pg. 288

90
Q

What are the effects of a stenosis?

A 
Change in flow direction 
Increased velocity as vessel narrows 
Turbulence downstream from the stenosis 
Pressure gradient across the stenosis 
Loss of pulsatility pg. 292
91
Q

What is the hyrdrostatic pressure in different parts of the body while standing and laying supine?

A 
Standing: 
Finger in air: -50 mmHg 
Heart: 0 mmHg 
Waist: 50 mmHg 
Knee: 75 mmHg 
Ankle: 100 mmHg 
pg. 298

Supine: 0 mmHg everywhere
pg. 297

92
Q

What is coaptation?

A

Compressing a vessel Per Beth

93
Q

What happens to the pressure in different parts of the body while inhaling and exhaling?

A 
Inspiration: 
Diaphragm moves down 
Thoracic pressure decreases 
Abdominal pressure increases 
Venous return to heart increases 
Venous flow in legs decreases 
Expiration: 
Diaphragm moves up 
Thoracic pressure increases 
Abdominal pressure decreases 
Venous return to heart decreases 
Venous flow in legs increases pg. 301
94
Q

What is the Doppler shift called when the sound source and the receiver are moving farther apart?

A

Negative Doppler shift pg. 305

95
Q

What is the typical range for a Doppler shift?

A

20 Hz - 20,000 Hz pg. 304

96
Q

What is the phenomenon called when high velocities appear negative?

A

Aliasing pg. 315

97
Q

What are five ways that we can eliminate aliasing? Which is for appearance only?

A
  1. Adjust scale to its maximum
  2. Select a new ultrasonic view with a shallower sample volume
  3. Select a lower frequency transducer
  4. Use baseline shift - for appearance only
  5. Use continuous wave Doppler
    pg. 319 and 322
98
Q

What are the x-axis and y-axis for Doppler on a spectral analysis?

A

x-axis: time

y-axis: velocity pg. 307

99
Q

Doppler shift is inversely related to ___.

A

Propagation speed pg. 306

100
Q

What is unidirection Doppler?

A

Either flow away or towards the transducer? pg. 311

101
Q

If red blood cells are traveling toward the transducer, what kind of Doppler shift is this?

A

Positive Doppler shift pg. 304

102
Q

What is the primary advantage of pulsed Doppler?

A

Being able to see the exact location where the velocity is being measured called range resolution, range specificity, or freedom from range ambiguity artifact pg. 314

103
Q

What is the primary advantage of continuous wave Doppler?

A

accurately measures very high velocities pg. 312

104
Q

What is the disadvantage of using color Doppler?

A

aliasing pg. 325

105
Q

The area of interrogation on Doppler is called what?

A

sample volume pg. 339

106
Q

What tool has increased sensitivity to low flow states?

A

Power Doppler pg. 333

Continuous wave pg. 313

107
Q

Know all describing factors of an ultrasound image

A 
Hyperechoic 
Hypoechoic 
Anechoic 
Isoechoic 
Homogeneous 
Heterogeneous pg. 356
108
Q

Why do we have artifacts?

A

error in imaging from violation of assumptions
equipment malfunction/poor design
physics of ultrasound
operator error pg. 355

109
Q

Which artifact has equally spaced parallel lines?

A

Reverberation pg. 357

110
Q 
Which artifact is unrelated to the dimensions of ultrasound? 
A. Lateral resolution 
B. Depth resolution 
C. Slice Thickness 
D. Refraction
A

Refraction pg. 378

111
Q 
What artifact produces an incorrect number of reflectors? 
A. Propagation speed error 
B. Multipath 
C. Enhancement 
D. Side Lobes
A

Side lobe artifact pg. 377

112
Q

What is mirror image?

A

When sound reflects off a strong reflector and is redirected toward a second structure appears deeper than true reflector on a straight line pg. 363

113
Q

What kind of transducer do side lobes and grating lobes come from?

A

Side lobes created by mechanical probes Grating lobes created by array transducers pg. 367

114
Q

What are axial and lateral resolution artifacts?

A

Lateral occurs when a pair of side-by-side reflectors are closer than the width of the sound beam and they appear as 1.
Axial occurs when a long pulse strikes 2 closely spaced structures where one is in front of the other they appear as 1. pg. 370

115
Q

Where does edge shadow come from?

A

curved reflector pg. 360

116
Q

What is focal banding?

A

AKA focal enhancement

Hyperechoic side-to-side region from increased intensity at the focus pg. 362

117
Q

What is enhancement?

A

hyperechoic region below structure from the result of too little attenuation pg. 361

118
Q

What are speed errors?

A

When sound wave propagates through a medium at a speed other than that of soft tissue pg. 364

119
Q

What is speckle?

A

Noise resulting from the constructive and destructive interference of small sound wavelets pg. 374

120
Q

What is range ambiguity artifact?

A

Occurs when a reflecting structure is located deeper than the imaging depth of the image; reflector is located shallower on the image pg. 373

121
Q

What is cross talk?

A

mirror image artifact that appears on a spectral Doppler display pg. 363

122
Q

What is a tissue equivalent phantom? (2 questions)

A

Used to evaluate characteristics such as gray scale and tissue texture, and multi-focus and adjustable-focus phased array transducers Gray scale is evaluated pg. 382

123
Q

What are the rules for informed consent?

A

Patient must be competent and consent must be voluntary the goal is to allow patients to be knowledgeable of their health care pg. 393

124
Q

A perfect technique for example, MRI or Angio, that would deem 100% accurate with ultrasound is called what?

A

Gold Standard Per Beth

125
Q

What are we testing with quality assurance?

A

Validates the consistency of ultrasound images and the accuracy of measurement devices pg. 379

126
Q

According to the AIUM and FDA bioeffects intensity limits, what is the difference between focused and unfocused sound beams?

A

Unfocused beam is more likely to cause a rise in temperature because the beam spreads over a broad area pg. 549

127
Q

What is the first thing you should do when entering a patient’s room?

A

It is important to treat patients with respect. Therefore, the first action should be to introduce themselves to the patient.
p399

128
Q

What kind of transducer, if it’s crystals get destroyed, will have the whole image compromised?

A

mechanical pg 167

129
Q

What transducer is focused in all planes and at all depths?

A

Annular Phased Array Per Game Review

130
Q

What is the advantage of a 1.5 dimensional array transducer? What type of dimension are we looking at?

A

3D/4D.

Has the advantage of Elevational Resolution. pg 188

131
Q

What is the image shape for a vector array?

A

Trapezoidal

132
Q

What type of transducer has elements that are in a straight line?

A

Linear

133
Q

What transducer has circular rings and a common center?

A

Annular pg 179

134
Q

Which transducer has it’s elements in a bow shape?

A

Curved

135
Q

What does phased array mean?

A

adjustable pg 170

136
Q

Dropout of an image from top to bottom is produced by what type of transducer?

A

Linear Sequential Array

Convex/curve pg 180

137
Q

Dropout of an image from side to side is produced by what type of transducer?

A

Annular phased array pg 179

138
Q

Know all about mechanical probes

A

single crystal sector shaped image mechanical steering fixed focus pg 167

139
Q

What is dynamic aperture?

A

the “listening hole” it is a technique used to make a sound beam narrow over a greater range of depths. pg 194

140
Q

The ability to accurately locate a moving structure at any point or time is what?

A

Temporal Resolution Per Game Review

141
Q

What will degrade temporal resolution?

A

low frame rates pg 372

142
Q

If we double our depth of view, what happens to the frame rate?

A

1/2 Per Game Review

143
Q

What degrades temporal resolution?

A

low frame rates pg 372

144
Q

With a given Hz, how long will it take to make a single frame?

A

reciprocals, so for example given frequency is 30 Hz, it will take 1/30 sec to create a frame pg. 214

145
Q

Lateral resolution will improve with ___.

A

High frequency

Large Diameter Per Game Review

146
Q

The depth of a scan is 15 cm, there are 100 lines in the image. What are the number of pulses that make up the scan?

A

100 pulses pg. 213

147
Q

What is consistent with increased or improved spatial resolution?

A

high line density pg 372

148
Q

Which ultrasound system component organizes and times the functions?

A

Master Synchronizer Per Game Review

149
Q

What component of an ultrasound system creates the electrical signal that excites the PZT?

A

Pulser Per Game Review

150
Q

Know the anatomic areas of the TGC curve

A 
near gain 
delay 
slope 
knee 
far gain pg 228
151
Q

On a TGC curve, what location does attenuation take place?

A

Slope

152
Q

What creates the firing pattern for a phased array transducer?

A

Beam Former Per Game Review

153
Q

Of receiver functions, which treats signals differently depending on depth?

A

Compensation Per Game Review

154
Q

If an image is too dark or too bright the sonographer should decide between output power and receiver gain keeping what in mind?

A

ALARA Per Game Review

155
Q

Which receiver function affects only the weak signals, leaving the strong signals unchanged?

A

Reject Per Game Review

156
Q

If an image is dark in the near field but you can still see what’s in the far field, what should be adjusted?

A

TGC Per Game Review

157
Q

Which function will affect the strength of every pulse transmitted into the body?

A

Output Power Per Game Review Amplification Pg. 224

158
Q

What is signal to noise ratio?

A

a comparison of the meaningful information (signal) in an image, compared to the amount of contamination (noise) pg 219

159
Q

What are the describing words for intensity?

A

Bigness or spatial peak average temporal pulsed pg 69

160
Q

What is the dominating contributor to attenuation?

A

Absorption pg84

161
Q

How do you calculate attenuation?

A

total attenuation= attenuation coefficient x distance pg 85

162
Q

When can a patient revoke their consent?

A

Any time pg. 393

163
Q

Bigness parameters

A

Amplitude
Power
Intensity

164
Q

Five parameters to describe pulsed wave. It is adjustable? What is it determined by?

A

Pulse duration (time)- not adjustable, determined by source
Pulse repetition period (time)- adjustable, determined by source
Pulse repetition frequency (Hz)- adjustable, determined by source
Duty factor- adjustable, determined by source and medium
Spatial pulse length (distance)- not adjustable, determined by source

165
Q

Every 10 dB change means that the intensity will

A

increase ten times

166
Q

A reduction in the intensity of a sound beam to one-half of its original value is

A

-3 dB

167
Q

What is positioned in front of the PZT, is a 1/4 wavelength thick?

A

Matching layer

p 115

168
Q

If the frequency of the electrical excitation voltage of a pulsed wave transducer is 6 MHz, then the operating frequency of the transducer is 6 MHz.

A

False. With pulsed wave transducers, the frequency of sound is not determined by the electrical signal.
p 126

169
Q

If the frequency of the electrical excitation voltage of a continuous wave transducer is 6 MHz, then the operating frequency of the transducer is 6 MHz.

A

True. The frequency of the electrical voltage and the frequency of the sound beam are identical with continuous wave transducer.
p 127

170
Q

Which of the following probes creates a beam with the shallowest focus?

A

Smaller diameter, low frequency

p 138

171
Q

Which of the following probes creates a beam with the deepest focus?

A

Larger diameter, higher frequency

p136

172
Q

The impedance of a transducer active element is 1,900,000 Rayls, and the impedance of the skin is 1,400,000 Rayls. What is an acceptable impedance for the matching layer?

A

1,750,000
The impedance of the matching layer is between that of the active element and the skin
p 127

173
Q

With a pulsed wave transducer, frequency is determined by what two factors

A
  1. speed of sound in the PZT
  2. thickness of the PZT
    p123
174
Q

Which component helps determines the focal length of the sound beam?

A

Active element

p 131

175
Q

Intensities from largest to smallest

A

SPTP -> Im -> SPPA -> SPTA -> SATA

p74

176
Q

PORNN

A 
Perpendicular
Orthogonal
Right angle
90 degrees
Normal
177
Q

Thin half value vs Thick half value

A

Thin:

  • high frequency sound
  • media with high attenuation rate

Thick:

  • low frequency sound
  • media with low attenuation rate

p87

178
Q

Half value layer thickness depends on two factors

A

-the medium
-the frequency of sound
p87

179
Q

A sound wave with an intensity of 30 W/cm^2 strikes a boundary and is totally reflected. What is the intensity reflection coefficient?

A

100%

p94

180
Q

A sound wave with an intensity of 40 W/cm^2 strikes a boundary and is totally reflected. What is the reflected intensity?

A

40 W/cm^2

p94

181
Q

Contributors to attenuation

A
  1. Reflection
  2. Scattering
  3. Absorption
    p81
182
Q

Mechanistic Approach

A

A proposal that a specific mechanism has the potential to produce bioeffects.
Searches for a relationship between cause and effect.
p407

183
Q

Steady flow

A

Occurs when a fluid moves at a constant speed or velocity

p286

184
Q

Turbulent flow

A

Characterized by chaotic flow patterns in many different directions and at many speed
p288

185
Q

Velocity indicates

A

The speed or swiftness of a fluid moving from one location to another
“how fast?”
p285

186
Q

Low line density has a _____ sector

A

narrow

187
Q

High line density has a _____ sector

A

wide

188
Q

Multi-focusing improves

A

Lateral resolution

189
Q

Higher line density improves

A

Spatial resolution

LMC Ultrasound (32 decks)

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