Print Options

Card layout: ?

← Back to notecard set|Easy Notecards home page

Instructions for Side by Side Printing
  1. Print the notecards
  2. Fold each page in half along the solid vertical line
  3. Cut out the notecards by cutting along each horizontal dotted line
  4. Optional: Glue, tape or staple the ends of each notecard together
  1. Verify Front of pages is selected for Viewing and print the front of the notecards
  2. Select Back of pages for Viewing and print the back of the notecards
    NOTE: Since the back of the pages are printed in reverse order (last page is printed first), keep the pages in the same order as they were after Step 1. Also, be sure to feed the pages in the same direction as you did in Step 1.
  3. Cut out the notecards by cutting along each horizontal and vertical dotted line
To print: Ctrl+PPrint as a list

185 notecards = 47 pages (4 cards per page)

Viewing:

Chapter 6 Artifacts notes

front 1

Artifact

back 1

anything that is not properly indicative of the structures or events

front 2

Benefits to artifacts

back 2

shadowing
enhancement

- tell the difference between solid and fluid
- characterize masses

front 3

Negative attributes of artifacts

back 3

improper location
wrong size
wrong shape
wrong acoustical properties
absent
present
absuring

front 4

Artifacts can be due to improper equipment settings

back 4

receiver gain
compensation settings
pre/post processing
range ambiguity

front 5

Artifacts can be due to ultrasound pysics

back 5

ring down
enhancement
edge shadowing
shadowing
reverberation
mirroring

front 6

Artifacts occur from assumptions

back 6

straight line
along the beam axis
amplitude related to the object struck
speed of sound in soft tissue

front 7

Doppler artifacts

back 7

incorrect spectral flow
aliasing
range ambiguity
mirror imaging
speckle

front 8

Slice thickness artifact

back 8

when 3D is flattened to convert to 2D external echoes show up in the image

front 9

Cause of slice thickness artifact

back 9

beam is not razor thin

front 10

AKA slice thickness artifact

back 10

section thickness
elevational resolution
partial volume artifact

front 11

What transducers are prone to slice thickness artifacts?

back 11

linear array

due to poor elevational resolution

front 12

why are machines good at axial resolution?

back 12

axial resolution does not change with depth

front 13

what artifacts is similar to multipath?

back 13

mirror

front 14

What causes multipath?

back 14

returning echoes do not return in a direct line

front 15

Multipath

back 15

gives wrong depth

front 16

cause of acoustic speckle

back 16

small amplitudes of sound waves interfering with each other

front 17

Acoustic speckle

back 17

liver

specular reflections

incorrect texture

front 18

How to improve acoustic speckle?

back 18

THI

front 19

What are the problems associated with acoustic speckle?

back 19

if too bad you will not be able to see (fat encompassing)

liver - pathological degrees of fatty filtration

front 20

Reverberation

back 20

bouncy ball

multiple echos (strong reflectors) that appear on the screen

multiple bounces between two or more surfaces

always equal distance

normal declining intensity

front 21

Ring down artifact

back 21

ring down occurs with gas filled loops of bowel

tends to occur with dirty shadowing

front 22

Comet trails

back 22

squeezed out reverberation

reflectors close

front 23

mirror image

back 23

and improper location caused by a change in propagation speed

caused by an adjacent strong reflector

front 24

What frequently causes mirror image?

back 24

diaphragm

front 25

Spectral mirroring

back 25

when spectral doppler appears in both sides of the baseline

front 26

what is a common cause of spectral doppler?

back 26

receiver gain too high

front 27

How do you fix spectral mirroring?

back 27

change angle
turn down receiver gain
change to higher frequency

front 28

What type of transducer produces side lobes?

back 28

single element

front 29

What type of transducer produces grating lobes?

back 29

array transducers

front 30

What causes lobes?

back 30

weak beams that might otherwise be ignored hit a strong reflector.

the reflected echoes become misplaced.

front 31

How do you get rid of lobes?

back 31

subdicing the element

using dynamic apodization

front 32

apodization

back 32

weakening of the outside elements

listening is decreased on the side

front 33

How do speed errors occur?

back 33

system works on the assumption that sound will make a round trip through soft tissue in 13 μs/cm

front 34

Where is the object placed if the speed is faster than 13 μs/cm?

back 34

closer

front 35

Where is the object placed if the speed is slower than 13 μs/cm?

back 35

farther

front 36

Split off artifact

back 36

object in front of another object causes the sound to travel faster or slower only on a portion of the second object. Part of the object usually the diaphragm is placed incorrectly and the object appears cut

front 37

step off artifact

back 37

aka split off artifact

front 38

cut artifact

back 38

aka split off artifact

front 39

What causes Range ambiguity?

back 39

caused by deep echoes from a previous pulse

front 40

what is range ambiguity?

back 40

object is placed closer and near the scan plane

front 41

How can you correct range ambiguity?

back 41

Change frequency

change depth

change PRF

most systems will adjust PRF

front 42

What is shadowing

back 42

shadows distal to strong attenuator

front 43

What causes shadowing?

back 43

strong reflector bouncing all sound back imediately

strong absorber - no echoes left to return

front 44

What causes edge shadowing?

back 44

reflections bouncing away when hitting a curved object - none return

front 45

Dirty shadowing

back 45

usually occurs with bowels

shadowing when internal echoes are present

front 46

What is enhancement

back 46

hyperechoic areas distal to a a weak attenuator

cysts

front 47

What causes enhancement

back 47

an unexpected increase in amplitude

front 48

focal enhancement

back 48

increased enhancement at the focus

front 49

What can you do to correct focal enhancement?

back 49

spacial compounding

front 50

what is thru transmission?

back 50

aka enhancement

front 51

Aliasing

back 51

peaks cut off and place on bottom

speeding ticket

blood travels faster than the nyquist limit

front 52

What can cause aliasing?

back 52

insufficient spatial sampling

insufficient temporal sampling

front 53

What can correct aliasing?

back 53

raise PRF - chance of range ambiguity

increase doppler shift

shift baseline - cosmetic

switch to continuous wave

front 54

What is the nyquist limit?

back 54

1/2 PRF

front 55

PRF

back 55

pulses per second

front 56

Artifact cause

axial resolution

back 56

pulse length

front 57

Artifact cause

lateral resolution

back 57

pulse width

front 58

Artifact cause

section thickness

back 58

pulse width

front 59

Artifact cause

speckle

back 59

interference

front 60

Artifact cause

reverberation

back 60

multiple reflections

front 61

Artifact cause

refraction

back 61

refraction

front 62

Artifact cause

multipath

back 62

multiple reflections

front 63

Artifact cause

mirror image

back 63

multiple reflections

front 64

Artifact cause

side lobes

back 64

side lobes

front 65

Artifact cause

grating lobes

back 65

grating lobes

front 66

Artifact cause

comet trail

back 66

reverberation

front 67

Artifact cause

ring down

back 67

resonance

front 68

Artifact cause

speed error

back 68

speed error

front 69

Artifact cause

range ambiguity

back 69

high PRF

front 70

Artifact cause

shadowing

back 70

high attenuation

front 71

Artifact cause

enhancement

back 71

low attenuation

front 72

Artifact cause

edge shadowing

back 72

refraction

front 73

Artifact cause

focal enhancement

back 73

focusing

front 74

Artifact cause

aliasing

back 74

low PRF

front 75

Artifact cause

spectral mirroring

back 75

high doppler gain

front 76

Which testing is the most challenging?

back 76

Doppler

front 77

What part of the system is most likely to break down?

back 77

transducer

electric shock

front 78

Why do we perform performance testing?

back 78

to prevent degradation of image

front 79

What do acoustic output testers evaluate?

back 79

beam former and transducer acting together as a source of ultrasound

front 80

what do flow testers evaluate?

back 80

Doppler

front 81

What do detail testers evaluate?

back 81

lateral and axial resolution

front 82

What so output testers evaluate?

back 82

sound output

front 83

What is the goal of system testers?

back 83

detect gradual changes in system performance

front 84

Who does the responsibility of quality assurance rest?

back 84

sonographer

front 85

How often should equipment be tested?

back 85

one a month

front 86

Perfecting these methods is _____ but must be done & must be ______.

back 86

difficult

repeatable

front 87

What do AIUM test objects test for?

back 87

slice thickness

beam width

detail resolution\depth accuaracy

measurement accuracy

dead zone

front 88

What is the main problem with AIUM test objects?

back 88

no attenuation properties

front 89

What is the AIUM test object usually filled with?

back 89

water

but sometimes no water

front 90

What is the main advantage of the AIUM test object

back 90

price

front 91

What does the tissue/cyst phantum test for?

back 91

detail resolution

dynamic range

time gain compensation

contrast resolution

front 92

What does the cyst phantom contain

back 92

columns of simulated cysts

front 93

How do you fix lateral smearing?

back 93

decrease depth (increases frame rate - improves temporal resolution)

front 94

Describe the constructions of the tissue phantum

back 94

rubber face & sides

plexiglass base

cosists of cystic, nylon other materials

front 95

What is the test phantom filled with?

back 95

gel - 1.54

rubber - 1.45

front 96

How would you test the dead zone?

back 96

front 97

How do you evaluate cysts

back 97

front 98

What does the cyst evaluation show?

back 98

size and depth variation

front 99

How would you evaluate axial resolution?

back 99

front 100

What does this test for?

back 100

axial resolution

smallest distance two pins can be seen as two separate pins

front 101

How would you evaluate vertical registration?

back 101

front 102

What does this test for?

back 102

vertical registration / range accuracy

ability to display echoes at the proper depth or top line

front 103

How would you evaluate Horizontal registration?

back 103

front 104

What does this test for?

back 104

Horizontal registration

the ability to position echoes in the their correct position along a line that is perpendicular to the ultrasound beam

front 105

How would you evaluate lateral resolution?

back 105

front 106

What does this test for?

back 106

lateral resolution

minimum distance two pins can be seen as two separate pins at a specific depth

front 107

How would you evaluate grey scale?

back 107

front 108

What does this test for?

back 108

grayscale / contrast resolution

the ability to discriminate between 2 different objects that have different shades of grey

front 109

What is the difference between these two test for contrast resolution?

back 109

the first one has size variation

the second one has depth variation

front 110

Minimum sensitivity

back 110

start by making TGC flat then increase gain from minimum value

the point the echo appears on screen is minimum sensitivity

front 111

Normal sensitivity

back 111

is the point in which all the pins on an AIUM test object are displayed

front 112

Sensitivity

back 112

is the range that echoes are barely visible to fully sensitivity

front 113

lateral resolution

back 113

the minimum distance that two rods are displayed as two separate images at a specific depth

front 114

Focal zone

back 114

the depth at which the intensity is the highest and beam is the narrowest

this may be found using beam profiler or hydrophone

front 115

Dynamic range / greyscale

back 115

change in gain should result in a change in greyscale

front 116

vertical registration / range accuracy

back 116

the machines ability to display echoes at the proper depth

front 117

depth calibration

back 117

the accuracy of B mode, m mode and A mode on displaying the depth of reflectors

front 118

horisontal calibration

back 118

the machines ability to position echoes in the correct postiion perpendicular to the U/S beam

front 119

longitudinal resolution

back 119

smallest distance at which two pins are displayed as two separate echoes in their position parallel to the beam

front 120

What do the Doppler performance tools evaluate?

back 120

the effective position of the Doppler beam (penetration)

accuracy of measured flow

accuracy volume and flow speed

front 121

What do we use for Doppler testing?

back 121

Blood tissue phantom

Doppler testing object

front 122

What is a Blood tissue phantom

back 122

Doppler testing the mimicks blood

  • sephadex in water
  • polystyrene microspheres in water/glycerol
  • water + machine cutting oil
  • starch suspensions

front 123

What is a Doppler testing object?

back 123

Doppler test object uses controlled movement of strings

  • moving solid object
  • usually a string ultrasound
    • pulsatile motions
    • reverse motion

front 124

What are the disadvantages of the Doppler string phantom?

back 124

  1. over estimates peak velocities
  2. causes artifactual spectral broadening

front 125

What does a Blood tissue phantom contain?

back 125

an image face

medium

a flow conduit

pump

blood mimick

reservoir

front 126

How does a Blood tissue phantom work?

back 126

complex

tube connects to a pump

pumps an echogenic fluid through out a known velocity simulates a stenosis.

front 127

What is a microprobe?

back 127

small transducer on a hollow needle

front 128

What is a hydrophone?

back 128

large piezoelectric membrane with electrodes on both sides

front 129

What are microprobe and hydrophone used for?

back 129

Measure intensity

produce a waveform on an oscilloscope

front 130

What do microprobe and hydrophone use as a piezoelectric material?

back 130

PVDF

front 131

How do microprobe and hydrophone work?

back 131

receive sound from all directions measure pressure at a given point within the beam in response to the varying pressure

the hydrophone produces a varying voltage

front 132

What is the voltage produced by a hydrophone displayed on?

back 132

oscilloscope

front 133

What does an oscilloscope display?

back 133

bandwidth

front 134

What do hydrophones measure?

back 134

frequency

PRF

duty factor

pressure amplitude

wavelength

SPL

intensity

front 135

Which type of U/S produces the greatest acoustic output?

back 135

Pulsed Spectral Doppler

Color Doppler

M mode

B mode

front 136

Intensity and output indexes have already been copulated using a ______.

back 136

hydrophone

front 137

What is the #1 assumption of risk?

back 137

U/S is energy and any energy applied to human cells can cause change

front 138

What is the rule of U/S?

back 138

risk benefit ratio

any possible benefit must outweigh possible risks

  • whenever possible
    • increase benefit
    • decrease risk

front 139

How do we increase benefit?

back 139

Better equipment

  • choose best greatest depth higher resolution - output gain will not need to be increased
  • harmonic imaging
  • appropriate transducer

Better operator

  • knowledgable
    • formal
    • informal learning
  • experience

front 140

How do we decrease risk?

back 140

decrease output/exposure

  • use only when indicated
  • minimize length of exam

decrease bioeffects

  • lower exposure intensity
  • decrease length of exam
  • use low output imaging methods

front 141

Do you need a Doctors orders for an ultrasound exam?

back 141

Yes

medical device regulates by the FDA

front 142

What are the two types of mechanical bioeffects?

back 142

cavitation

radiation

front 143

What is radiation?

back 143

the amount of force that a beam exerts on an absorber or reflector

front 144

What are the two types of bioeffects?

back 144

heating - attenuation of U/S is primary by heat

cavitation - motion of microbubbles

front 145

What is heating primarily due to?

back 145

absorption

front 146

Why does absorption cause heating?

back 146

absorption involves conversion of U/S to heat

front 147

U/S produce a temp. rise as it propagates through tissue

back 147

no data

front 148

What happens to heat when intensity goes up?

back 148

rises

front 149

What happens to heat when frequency goes up?

back 149

rises

front 150

What can Rayleighs scattering cause?

back 150

Thermal injury

front 151

Where are temperature elevations more likely to occur?

back 151

tissue-bone interface

front 152

What area is of great concern to thermal injury?

back 152

soft tissue adjacent to bone in a fetus

front 153

What is SPTA associated with?

back 153

tissue heating

front 154

What exam can be used without fear?

back 154

any exam that causes elevation in temperature of less than 2 degrees Celcius

front 155

What exam may cause harm in a fetus?

back 155

an exam that causes an elevation of temperature of greater than 41 degrees Celcius

front 156

What does Rayleigh scattering cause?

back 156

RBC to scatter

front 157

What is Rayleigh scattering?

back 157

when the wavelength of the incident sound beam is smaller than the size of the RBC

front 158

Which causes higher Temperature elevation Pulsed wave or Continuous wave?

back 158

CW causes higher temperature elevation

front 159

Which causes higher Temperature elevation Focused or unfocused?

back 159

unfocused causes higher temperature elevation

* focused has a narrow beam and heat is easily dispersed

front 160

What is cavitation?

back 160

the production and behavior of bubbles in a liquid medium

front 161

Where would a sound wave may cause cavitation?

back 161

Nucleation sites

tissue with gas bubbles

front 162

What are the two types of cavitation?

back 162

stable cavitation

transient cavitation

front 163

What is stable cavitation?

back 163

expand and contract

bubbles that oscillate in diameter with the passing pressure of a sound wave

bubbles don't burst

causes shear stress - cutting force

front 164

What does shear force cause?

back 164

microstreaming

front 165

What is microstreaming?

back 165

rapid rotational flow that occurs in intact blood vessels

front 166

What is shear stress?

back 166

cutting force

front 167

What is transient cavitation?

back 167

bubbles expand and collapse violently

bubbles burst

front 168

What is another name for transient cavitation?

back 168

Collapse / inertial cavitation

front 169

What does transient cavitation cause?

back 169

destructive effects

shockwaves

light emissions

high temperature

front 170

What is Thermal index?

back 170

heat production index -

deals with bioeffects caused by heating

front 171

If a machine can exceed thermal or mechanical indexes what must be?

back 171

acoustic output displayed

front 172

What is Mechanical index

back 172

Motion production index -

deals with bioeffects caused by cavitation

front 173

What is the thermal index measured in?

back 173

degrees celcius

front 174

Which display is preferred SPTA or Thermal index?

back 174

Thermal index - more accurate

front 175

What should SPTA be below?

back 175

720 mw/cm2

front 176

TIS

back 176

Thermal index soft tissue

front 177

TIB

back 177

Thermal index bone

front 178

TIC

back 178

Thermal index cranial

front 179

TI of 2 or less =

back 179

expected heating of 2 degrees or less

front 180

Mechanical index formula

back 180

MI = derated peak rarefractional pressure / sqrt (U/S center frequency

front 181

What is threshold for MI?

back 181

.3 or less

front 182

What is normal body temperature?

back 182

37 degrees C

front 183

What is the max body temp rise?

back 183

39 degrees C

front 184

C to F

back 184

37°C x 9/5 + 32 = 98.6°F

front 185

F to C

back 185

(98.6°F - 32) x 1.8 = 37°C

(98.6°F - 32) x 5/9 = 37°C