Physics 2 Final Exam Flashcards
1
Q
What is the frequency of a transducer if the period is 25 million cycles/ sec?
A
25 MHz
Pg. 21
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
3
Q
What are the ultrasound parameters? Which are determined by only the sound source and which are determined by both the sound source and the medium?
A
Sound Source: Period Frequency Amplitude Power Intensity Pg.40 Pulse duration PRP PRF Duty Factor Pg 63
Sound Source & Medium: Wavelength Pg. 40 Spatial Pulse Length Pg. 63
4
Q
If intensity remains the same, while power is doubled, what happens to the beam area?
A
Doubled
Pg 44
5
Q
What are the acoustic variables?
A
Pressure (pascals)
Density (kg/cm^3)
Distance (cm,mm)
Pg 12
6
Q
What would create the longest wavelength?
A
The lower the frequency, the longer the wavelength
pg. 34
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
8
Q
What scale do we use for decibels?
A
Logarithmic
Pg 77
9
Q
What will intensity do if you have 3 dBs?
A
Intensity is doubled at 3dB
Pg 78
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
11
Q
Rayleigh scattering is related to ___.
A
Frequency^4
12
Q
Soft tissue attenuation coefficient is directly related to ___.
A
Frequency
Attenuation coefficient= 0.5dB/cm/MHz
pg. 85
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
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
15
Q
What happens when we exceed the Curie point?
A
Depolarization
Pg 120
16
Q
Which component of a transducer reduces ringing of a pulse?
A
Backing material
“Damping element”
Pg 115
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)
18
Q
What resolution is improved by damping material?
A
Axial
Pg 115
Longitudinal
pg. 126
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
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
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
22
Q
Which component of a transducer contains cork?
A
Acoustic insulator
Pg 115
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
24
Q
How are frequency and near zone length related?
A
Directly
Pg 135
25
Anatomy of a sound wave (5 questions)
- 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
26
How is the focal length of a sound beam determined?
1) Transducer diameter
2) Frequency of sound
pg. 135
27
What is the spread of a sound beam in the far field?
Divergence
| pg. 139
28
What will create the best lateral resolution based on frequency and diameter?
The largest diameter and highest frequency
| pg. 153
29
LARRD (multiple questions)
```
Longitudinal
Axial
Range
Radial
Depth
-parallel to beam's axis
-best with less ringing and high frequency
pg. 146
```
30
LATA (multiple questions)
```
Lateral
Angular
Transverse
Azimuthal
- perpendicular to beam's axis
- best with decrease FOV and at focus
pg. 153
```
31
What is lateral resolution?
the ability to distinguish 2 structures perpendicular to beam
pg. 151
32
Which intensity is most important when it comes to biological effects?
SPTA
| pg. 74
33
Which intensity is considered the maximum?
Peak
| Pg 69
34
What are the units for intensity?
W/cm^2
| pg. 73
35
What are the six different kinds of intensity?
```
spatial
peak
average
temporal
pulsed
pg 69 only found 5
```
36
What is an incident of a sound wave?
The angle at which the wave strikes the boundary.
```
Normal (PORNN)
perpendicular
orthogonal
right
90
```
Oblique=anything other than 90degree
37
What is the difference between transmission, reflection, and incident intensity? (6 questions)
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
pg 92
38
What is the half value layer thickness?
the distance sound travels in a tissue that reduces te intensity of sound to 1/2 of its original value.
pg 87
39
What is the angle degree for normal incidence?
90
40
What is the intensity reflection coefficient? (3 questions)
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
41
To have normal incidence, you have to have different what?
difference in acoustic impedance.
| pg 88
42
Specular reflections arise from what?
The sound is reflected in only one direction in an organized manner.
When it strikes a smooth boundary.
pg 81
43
What is the term used to describe transmission with a bend?
refraction
| pg 100
44
What can happen with both oblique incidence and different propagation speeds?
Refraction
| pg 101
45
Snell's Law describes what?
The physics of refraction
| pg. 102
46
What is it called when two sound waves are traveling towards something and they both arrive at the same time?
Interference
| Pg 18
47
Thumbs up and thumbs down rule (stiffness and density)
Stiffness directly related to speed
Density inversely related to speed
pg. 39
48
What is attenuation?
a decrease in intensity, power and amplitude as the sound travels through the medium
pg 80
49
Impedence is a characteristic of what?
Medium only
| pg 88
50
What type of transducer and frequency do we use on different parts of the body?
Small parts: Linear, High frequency
| Abdomen: Convex, Lower frequency
51
What is the ability to distinguish between two structures?
resolution
| pg. 149
52
What is the best choice for attenuation coefficient in soft tissue?
one-half of the frequency
| pg 85
53
Attenuation is determined by what two factors?
path length
frequency
pg 80
54
What is the term used to describe the redirection of sound in many directions?
Scattering
| pg 82
55
What do we consider a rough boundary?
most interfaces in the body
| pg. 82
56
What is time of flight?
the elapsed time from pulse creation to pulse reception
| pg. 107
57
What is Q-factor?
Q-factor = main frequency/bandwidth
Imaging probes have a low-Q
pg. 119
58
All the different names used to describe time of flight
Go return time
| pg. 107
59
What is the 13 microsecond rule?
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
60
When you change your depth, what happens to PRP?
Doubles
Per Game Review
Shallow Depth = Short PRP
pg. 109
61
Axial resolution deals with structures that are located where on the sound beam?
Parallel
| Per Game Review pg. 145
62
What happens to the numerical value of LARRD as frequency increases?
Decreases
| Per Game Review pg. 148
63
If you are given a frequency, what will have the best axial resolution? # of cycles
High frequency
Fewer cycles per pulse
pg. 148
64
Why is it difficult to study biological effects in living tissue?
Absorption (biggest reason), scattering and reflection
| pg. 170
65
What is the empirical approach?
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
66
What is the difference between stable cavitation and transient cavitation?
Stable
oscillating bubble
microstreamng and shear stresses
lower MI
Transient (normal, inertial)
bursting bubble
shock waves and very high temperatures
higher MI
pg. 411
67
What is the primary investigative technique used in epidemiology?
Reviewing of the charts
| Per Game Review
68
What is the most common intensity that is involved with tissue heating?
SPTA
| pg. 74
69
How do we study biological effects of non-living things?
in vitro
| pg. 405
70
Which will have the least amount of temperature elevation, focused or unfocused sound beams?
Focused sound beams
| per Game Review
71
What should we do if we find a broken housing or a frayed wire on an ultrasound machine?
Do not use it
72
When is it okay to perform an ultrasound on a patient?
When the benefits outweigh the risks
| pg. 405
73
What is the x-axis and y-axis on A, B, and M Mode?
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
74
A Mode
Amplitude Mode appearing as a series of upward spikes (big city skyline)
pg. 159-160
75
B Mode
Brightness Mode appearing as a line of dots of varying brightness, first form of gray scale imaging
pg. 161
76
M Mode
Motion Mode appearing as a group of horizontal wavy lines (heart rate)
pg. 162
77
What must we have to have gray scale imaging?
scan converter
| Per Game Review
78
What is the difference between pre-processing and post-processing?
Pre-processing is manipulation of image data before storage
Post-processing is manipulation of image data after stoarge
pg. 249
79
What is spatial compouding?
method of using sonographic information from several different imaging angles to produce 1 single image
pg. 254
80
What is fill-in interpolation?
method of constructing new simulated data points to fill in the gaps
pg. 257
81
What is persistence?
AKA temporal compounding or averaging
image processing technique that continues to display information from older images, which smooths the image
pg. 256
82
What is edge enhancement?
image processing method that makes pictures look sharper
| pg. 255
83
What are the advantages of the PACS system?
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
When sending the signal from the transducer to the receiver, what form is the information in? (refer to the analog to digital diagram on pg. 247)
analog to digital form
| pg. 247
85
What do contrast agents need to be?
```
Safe
Metabolically inert
Long lasting
Strong reflector of ultrasound
Small enough to pass through capillaries
pg. 278
```
86
What is harmonic imaging? (convert harmonic frequency to fundamental frequency)
harmonic imaging is the creatioin of an image from sound reflections at twice the frequency of the transmitted sound
pg. 269
87
What is the difference between pulsatile and phasic flow?
Pulsatile flow occurs when blood moves with a variable velocity (arterial)
Phasic flow occurs when blood moves with a variable velocity (venous)
pg. 286
88
What are the different types of laminar flow?
Plug flow: all layers and blood cells travel at the same velocity
Parabolic flow: flow has bullet-shaped profile
pg. 287.vr t
89
What is the Reynold's number for turbulent flow?
greater than 2000
| pg. 288
90
What are the effects of a stenosis?
```
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
What is the hyrdrostatic pressure in different parts of the body while standing and laying supine?
```
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
What is coaptation?
Compressing a vessel
| Per Beth
93
What happens to the pressure in different parts of the body while inhaling and exhaling?
```
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
What is the Doppler shift called when the sound source and the receiver are moving farther apart?
Negative Doppler shift
| pg. 305
95
What is the typical range for a Doppler shift?
20 Hz - 20,000 Hz
| pg. 304
96
What is the phenomenon called when high velocities appear negative?
Aliasing
| pg. 315
97
What are five ways that we can eliminate aliasing? Which is for appearance only?
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
What are the x-axis and y-axis for Doppler on a spectral analysis?
x-axis: time
y-axis: velocity
pg. 307
99
Doppler shift is inversely related to ___.
Propagation speed
| pg. 306
100
What is unidirection Doppler?
Either flow away or towards the transducer?
| pg. 311
101
If red blood cells are traveling toward the transducer, what kind of Doppler shift is this?
Positive Doppler shift
| pg. 304
102
What is the primary advantage of pulsed Doppler?
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
What is the primary advantage of continuous wave Doppler?
accurately measures very high velocities
| pg. 312
104
What is the disadvantage of using color Doppler?
aliasing
| pg. 325
105
The area of interrogation on Doppler is called what?
sample volume
| pg. 339
106
What tool has increased sensitivity to low flow states?
Power Doppler
pg. 333
Continuous wave
pg. 313
107
Know all describing factors of an ultrasound image
```
Hyperechoic
Hypoechoic
Anechoic
Isoechoic
Homogeneous
Heterogeneous
pg. 356
```
108
Why do we have artifacts?
```
error in imaging from
violation of assumptions
equipment malfunction/poor design
physics of ultrasound
operator error
pg. 355
```
109
Which artifact has equally spaced parallel lines?
Reverberation
| pg. 357
110
```
Which artifact is unrelated to the dimensions of ultrasound?
A. Lateral resolution
B. Depth resolution
C. Slice Thickness
D. Refraction
```
Refraction
| pg. 378
111
```
What artifact produces an incorrect number of reflectors?
A. Propagation speed error
B. Multipath
C. Enhancement
D. Side Lobes
```
Side lobe artifact
| pg. 377
112
What is mirror image?
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
What kind of transducer do side lobes and grating lobes come from?
Side lobes created by mechanical probes
Grating lobes created by array transducers
pg. 367
114
What are axial and lateral resolution artifacts?
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
Where does edge shadow come from?
curved reflector
| pg. 360
116
What is focal banding?
AKA focal enhancement
Hyperechoic side-to-side region from increased intensity at the focus
pg. 362
117
What is enhancement?
hyperechoic region below structure from the result of too little attenuation
pg. 361
118
What are speed errors?
When sound wave propagates through a medium at a speed other than that of soft tissue
pg. 364
119
What is speckle?
Noise resulting from the constructive and destructive interference of small sound wavelets
pg. 374
120
What is range ambiguity artifact?
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
What is cross talk?
mirror image artifact that appears on a spectral Doppler display
pg. 363
122
What is a tissue equivalent phantom? (2 questions)
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
What are the rules for informed consent?
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
A perfect technique for example, MRI or Angio, that would deem 100% accurate with ultrasound is called what?
Gold Standard
| Per Beth
125
What are we testing with quality assurance?
Validates the consistency of ultrasound images and the accuracy of measurement devices
pg. 379
126
According to the AIUM and FDA bioeffects intensity limits, what is the difference between focused and unfocused sound beams?
Unfocused beam is more likely to cause a rise in temperature because the beam spreads over a broad area
pg. 549
127
What is the first thing you should do when entering a patient's room?
greet patient and wash your hands???
128
What kind of transducer, if it's crystals get destroyed, will have the whole image compromised?
mechanical
| pg 167
129
What transducer is focused in all planes and at all depths?
Annular Phased Array
| Per Game Review
130
What is the advantage of a 1.5 dimensional array transducer? What type of dimension are we looking at?
3D/4D. Has the advantage of Elevational Resolution.
| pg 188
131
What is the image shape for a vector array?
Trapezoidal
132
What type of transducer has elements that are in a straight line?
Linear
133
What transducer has circular rings and a common center?
Annular
| pg 179
134
Which transducer has it's elements in a bow shape?
Curved
135
What does phased array mean?
adjustable
| pg 170
136
Dropout of an image from top to bottom is produced by what type of transducer?
Linear Sequential Array
Convex/curve
pg 180
137
Dropout of an image from side to side is produced by what type of transducer?
Annular phased array
| pg 179
138
Know all about mechanical probes
```
single crystal
sector shaped image
mechanical steering
fixed focus
pg 167
```
139
What is dynamic aperture?
the "listening hole" it is a technique used to make a sound beam narrow over a greater range of depths.
pg 194
140
The ability to accurately locate a moving structure at any point or time is what?
Temporal Resolution
| Per Game Review
141
What will degrade temporal resolution?
low frame rates
| pg 372
142
If we double our depth of view, what happens to the frame rate?
1/2
| Per Game Review
143
What degrades temporal resolution?
low frame rates
| pg 372
144
With a given Hz, how long will it take to make a single frame?
reciprocals, so for example given frequency is 30 Hz, it will take 1/30 sec to create a frame
pg. 214
145
Lateral resolution will improve with ___.
High frequency
Large Diameter
Per Game Review
146
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?
100 pulses
| pg. 213
147
What is consistent with increased or improved spatial resolution?
high line density
| pg 372
148
Which ultrasound system component organizes and times the functions?
Master Synchronizer
| Per Game Review
149
What component of an ultrasound system creates the electrical signal that excites the PZT?
Pulser
| Per Game Review
150
Know the anatomic areas of the TGC curve
```
near gain
delay
slope
knee
far gain
pg 228
```
151
On a TGC curve, what location does attenuation take place?
Slope
152
What creates the firing pattern for a phased array transducer?
Beam Former
| Per Game Review
153
Of receiver functions, which treats signals differently depending on depth?
Compensation
| Per Game Review
154
If an image is too dark or too bright the sonographer should decide between output power and receiver gain keeping what in mind?
ALARA
| Per Game Review
155
Which receiver function affects only the weak signals, leaving the strong signals unchanged?
Reject
| Per Game Review
156
If an image is dark in the near field but you can still see what's in the far field, what should be adjusted?
TGC
| Per Game Review
157
Which function will affect the strength of every pulse transmitted into the body?
Output Power
Per Game Review
Amplification
Pg. 224
158
What is signal to noise ratio?
a comparison of the meaningful information (signal) in an image, compared to the amount of contamination (noise)
pg 219
159
What are the describing words for intensity?
```
Bigness or
spatial
peak
average
temporal
pulsed
pg 69
```
160
What is the dominating contributor to attenuation?
Absorption
| pg84
161
How do you calculate attenuation?
total attenuation= attenuation coefficient x distance pg 85
162
When can a patient revoke their consent?
Any time
| pg. 393
