Physics 2 Final

Front 1

Heterogeneous

Back 1

This term refers to tissue that is of mixed echogenicities

Front 2

Isoechoic

Back 2

Two tissues that are of the same echogenicity

Front 3

How many basic assumptions does the US machine operate under?

Back 3

7

Front 4

An artifact will appear if...

Back 4

Any one of the basic assumptions is violated

Front 5

Anechoic

Back 5

Without echo (black)

Front 6

What is an artifact

Back 6

An error in imaging

Front 7

7 basic assumptions

Back 7

Sound travels in straight line

Sound travels directly to a reflector and back

Sound always travels at 1540 msec in soft tissue

Reflections displayed are found only in main beams path

Imaging plane is extremely thin

Reflectors are as bright as the reflectors characteristics depict

All echoes are received before the next pulse is sent

Front 8

What type of object is created when two objects sit less that 1/2 SPL apart

Back 8

Appears as one object

Axial resolution

Front 9

How to correct an object less than 1/2 SPL apart

Back 9

Increase frequency to lower SPL

Front 10

Which resolution is affected by beam width

Back 10

Lateral resolution

Front 11

Lateral resolution

Back 11

If two objects are closer than the width of the beam they will appear as one

Front 12

Where is the width of the beam narrowedt

Back 12

At the focal point

Front 13

What type of xducer is the best at reducing slice thickness artifacts

Back 13

1 1/2 D array

Front 14

What type of interference is caused by other machines and equipment

Back 14

Electronic

Front 15

This artifact is created between two strong reflectors creating equally spaced artifacts down the image

Back 15

Reverberation

Front 16

What is reverberation

Back 16

An artifact that is created when sound bounces between two reflectorso

Front 17

What is ring down artifact

Back 17

Spaces similar to reverberation but squeezed out. Due to small gas bubbles that start to "ring"

Front 18

What artifact is created when sound bounces off of a strong reflector, creating an exact replica on the opposite side

Back 18

Mirror image

Front 19

Which vessel is the true vessel

Back 19

The artifact is always deeper to the true anatomy

Front 20

In multi-path artifact the assumption that is violated is the sound travels to a reflector and __________back to the transducer

Back 20

Directly

Front 21

What is multi-path reflector

Back 21

When sound bounces around reflectors before returning to the xducer

Not exact replicas

The image is a combination of all the things the sound hit before returning to the xducer

Front 22

When refraction artifact is displayed, the the anatomy sits_______ to the false anatomy

Back 22

Laterally

Front 23

What is refraction artifact

Back 23

When some sound travels in the correct direction that displays the correct anatomy, but the bent sound tells the machine to display anatomy to the side

Front 24

This artifact can be corrected through application and subdicing

Back 24

Love artifact

Front 25

What is lobe artifact

Back 25

When strong reflectors outside of the main beam are displayed because they have been insinuated by weak grating or side lobes.

Front 26

Side lobes are created by single crystal and mechanical xducers. ________ are created by array xducers

Back 26

Grating lobes

Front 27

Apodization

Back 27

Causes the beam former to send stronger electrical spikes to the center crystals so the main beam is strongest. Weaker spike are sent to side crystals reducing strength of the grating lobes

Front 28

This artifact is created when there is a difference in propagation speeds causing the sound beam to either travel faster or travel slower

Back 28

Speed error

Front 29

Speed error artifact

Back 29

If sound travels faster through a medium, the machine will display the anatomy more superficial. (Go-return time is shorter) slower sound will result in anatomy displayed deeper due to longer go-return timr

Front 30

This is the general term for artifacts that cause the go-return time to be affected

Back 30

Propagation artifact

Front 31

This is the general term that refers to artifacts that alter the rate at which sound weakens

Back 31

Attenuation artifact

Front 32

Attenuation artifact

Back 32

If sound weakens abnormally fast, we see hyperechoic tissue behind. If a structure does. It cause sound to weaken, the tissue appears hyperechoic

Front 33

This artifact occurs behind objects that absorb sound

Back 33

Shadowing

Front 34

Shadowing srtifact

Back 34

Typically with bone (sound absorber)

Front 35

Hypoechoic lines that extend off the sides of a curved structure due to simultaneous refraction and divergence

Back 35

Edge shadow

Front 36

Edge shadowing artifact

Back 36

Sound beam becomes very weak after it refracts and diverges off the side of the curved structures. This creates shadowing off the edge of the structure

Front 37

Enhancement artifact

Back 37

Happens behind structures that have abnormally low attenuation. We leave enhancement when it aids in a diagnosis

Front 38

What artifact occurs when the same wave form is displayed on both sides of the baseline

Back 38

Cross talk

Front 39

How to correct cross talk

Back 39

Reducing Doppler gain or trying a different angle

Front 40

Aliasing is an artifact because the machine incorrectly displays the velocity of the blood. Aliasing occurs when the velocity is over the ________

Back 40

Nyquist limit

Front 41

Aliasing displays:

Back 41

Flow direction incorrectly due to "wrap around" effect

Front 42

What artifact mimics an incorrectly placed TGC

Back 42

Focal banding

Front 43

Focal banding artifact

Back 43

The beam is strongest at the focal point. The display may show a band of hyperechoic tissue at the level of the focal point

Front 44

Using the machine incorrectly like using the wrong xducer or not optimizing gain is what type of error

Back 44

Operator error- a sonographer that is unfamiliar with their machine will produce suboptimal pictures

Front 45

Is no corrective actions fix an artifact on the display, this may be a ______ malfunction

Back 45

Machine- broken crystals can not be corrected and are a common cause of machine malfunction

Front 46

A common way to fix artifacts on our display is to try scanning at a different ______

Back 46

Angle

Front 47

This term means "no echoes" we strive for blood filled structures to appear this way

Back 47

Anechoic

Front 48

This artifact occurs in the near field due to wavelets interfering with each other

Back 48

Speckle

Front 49

This program is a legal and medical necessity that ensures the US systems are optimal

Back 49

QA

Front 50

Who can perform QA

Back 50

Physicist, biomedical engineers and sonographers

Front 51

QA programs must be performed periodically and _______

Back 51

Routinely. QA is done in set intervals, every month, every 3 months as predetermined by the QA program

Front 52

________ maintenance includes cleaning the US system components like the keyboard and track ball as well as running diagnostic test on the computer

Back 52

Preventative.

Front 53

Helps keep the machine running optimally.

Back 53

Preventative maintenance

Front 54

One reason for QA programs is to ________ proper operation of the US machine

Back 54

Guarantee

Front 55

One purpose of a QA program is to ______ gradual changes

Back 55

Detect

Front 56

When a QA program is in place, the machine will most likely be operating at its best, which reduces ______\

Back 56

Downtime

Front 57

A good QA program will improve patient care by ______ the number of non diagnostic exams and need for repeat exams

Back 57

Reducing

Front 58

QA methods must be ________

Back 58

Consistent

Front 59

These type of standards are preferred when testing. They are based in fact and are repeatable

Back 59

Objective

Front 60

Objective standards are

Back 60

Measurable and not based on opinion. This results in consistency

Front 61

This type of standard is based on opinion and may not be repeatable

Back 61

Subjective

Front 62

Subjective standards are

Back 62

Opinions and not based on factual information.

Front 63

What type of phantom measures the thickness of the beam

Back 63

Beam profiler

Front 64

Beam profiler measures the _________ ___________ of the beam

Back 64

Elevational thickness

Front 65

This type of phantom allows the US to travel at 1540 m/s

Back 65

Soft tissue

Front 66

This type of phantom comes in three different variations: vibrating string, vibrating belt and flow pattern

Back 66

Doppler

Front 67

When QA is done with the machine set at clinically appropriate settings, this tests the machines _______

Back 67

Sensitivity

Front 68

QA is performed with the same ________ each time. QA is also performed with the machines parameters _________

Back 68

Sensitivity, "maxed out"

Front 69

This area of the image is usually in the first few mm of the picture and is considered to be inaccurate

Back 69

Dead zone

Front 70

To compensate for a dead zone, a _____ _______ ______is used. The dead zone is tested by phantoms with pins that are very near the imaging surface

Back 70

Stand off pad

Front 71

________ accuracy tests the machines ability to display vertical and horizontal reflectors as well as correctly sized reflectors at various depth and lateral placement

Back 71

Registration

Front 72

The result of using ultrasound on living tissue can have adverse _______

Back 72

Bioeffects

Front 73

This device, also known as a microphone, can test multiple features of an ultrasound beam

Back 73

Hydrophone

Front 74

Measuring this type of force can indicate the intensity of the beam

Back 74

Radiation

Front 75

This method of beam testing uses light to see the shadow of the sound beam

Back 75

Acoustic- optics

Front 76

This device measures the total power of a beam by observing absorption

Back 76

Calorimeter

Front 77

This device is a small thermometer that measures the power of the beam in specific areas

Back 77

Thermocouple

Front 78

The ________ can be moved within a beam to test the power where it is located and the tip has absorbing material in it

Back 78

Thermocouple

Front 79

This method of testing US beams uses a substance that changes color based on the heat that is applied

Back 79

Liquid crystals

Front 80

This term refers to studies that are done on living subjects

Back 80

In-vivo

Front 81

In- vivo studies are performed on

Back 81

Lab animals- very few human studies are available

Front 82

This term refers to studies that are performed outside of a living subject

Back 82

In-vitro

Front 83

What approach to studies tries to find a relationship between cause and effect

Back 83

Mechanistic

Front 84

What type of studies look at exposure and effect

Back 84

Empirical

Front 85

This mechanism of bioeffects is concern because we know sound converted into heart as it is absorbed by soft tissue and because we know the body operates beast at 37 c

Back 85

Thermal

Front 86

Which interface is more Duce problem to heating

Back 86

TissueA bone interface. Bone absorbs a lot of sound and is more likely to heat up

Front 87

What term describes the j Tera Timon of small gas bubbles and Ultrasound

Back 87

Cavitstion

Front 88

What machine parameter measures the likelihood of cavitation occurrence

Back 88

Mechanical index

Front 89

Low MI vs high MI

Back 89

Lo MI's are more likely to cause stable cavitation. Higher MI's are going to lead to normal to inertial cavitation and increase the chance of bioeffects

Front 90

What term describes the interaction of small gas bubbles and ultrasound

Back 90

Cavitation

Front 91

This occurs when a sound source is moving towards or away from an object

Back 91

Doppler shift

Front 92

Doppler shifts are in the range of 20 Hz to 20,000 Hz. This means that they are in the _______ range

Back 92

Audible

Front 93

Which Doppler shift has an increased reflected frequency

Back 93

Positive

Front 94

What Doppler shift has a decreased reflected frequency

Back 94

Negative

Front 95

When speed and direction are known, what are we able to meausre

Back 95

Velocity

Front 96

What does velocity tessnu

Back 96

Speed (distance/time) and direction of flow

Front 97

What does the 3 in the Doppler equation account fir

Back 97

Transmit and receive frequencies

Front 98

1540 m/s is a constant number in ultrasound that is used for part of the Doppler equation

Back 98

Propagation speed

Front 99

Doppler shift relatikns

Back 99

If the Doppler shift increases or decreases, so must at least one of the other parameters

Front 100

The cosine of 0=1 when we are at a 0 degree or 180 degree incidence. This means the sound beam is ________ to the direction of flow

Back 100

Parallel

Front 101

What is the Doppler shift when cosine = 0

Back 101

Zero

Front 102

How many speakers does bidirectional Doppler use?

Back 102

2

Front 103

What is phase quadarture

Back 103

Above the baseline is typically positive Doppler shifts and below the baseline is typically negative

Front 104

What type of Doppler requires two crystals and cannot produce an atomic images and can measure high velocities

Back 104

Continuous wave

Front 105

Continuous wave Doppler is good at measuring high velocities, the pitfall is that the sonographer cannot choose exactly where they are sampling. This is referred to as______ _________

Back 105

Range ambiguity

Front 106

This type of imaging allows for Doppler and anatomical imaging to occur simultaneously

Back 106

Duplex imaging

Front 107

This type of Doppler allows for exact location of sample, but is not good at measuring high velocities

Back 107

Pulse wave doppler

Front 108

What term is defined as 1/2 PRF

Back 108

Nyquist limit

Front 109

How to increase PRF?

Back 109

Switch to a lower frequency xducer. This will also increase the nyquist limit

Front 110

PW xducers have this. It causes low q- factor, low sensitivity, and high dandwidths. Dedicated CW xducers do not have this. They have high q- factor, high sensitivity, and low bandwidths

Back 110

Backing material

Front 111

If you only have one xducer and adjusting PRF and the baseline do not correct aliasing, what else can you change

Back 111

Depth

Front 112

A sonographer has the Doppler gain set too high. How will any velocity measurements take. With this spectral waveform be

Back 112

Overestimated

Front 113

This machine setting will reduce the number of low level echoes displayed on the spectral tracing

Back 113

Wall filter

Front 114

Changing the ____ _____ can clean up the spectral display by getting rid of extra noise.

Back 114

Wall filter

Front 115

The type of color map where yellow is on the top and red is on the bottom is

Back 115

Velocity color map

Front 116

Velocity color map

Back 116

Assigns color to the average velocity found within the vessel

Front 117

What type of color map has red on the left and yellow on the right

Back 117

Variance color map

Front 118

Variance color map

Back 118

Show velocity and type of flow. Left side= laminar flow

Front 119

What does the black bar mean in between the red and blue on a color map

Back 119

No doppler shift

Front 120

This term is also known as ensemble. When they are large, color Doppler is more sensitive, but the frame rate decreases

Back 120

Packets

Front 121

What type of Doppler is also known as energy mode and does not indicate speed or direction

Back 121

Power

Front 122

To get an appropriate angle she. Using color Doppler, what can we do to the color box

Back 122

Steer

Front 123

This equation helps the machine to filter all the information coming back from blood vessels to create a waveform

Back 123

Fast Fourier transform

Front 124

This equations help the machine to determine the average velocity and choose a color to display during color doppler

Back 124

Autocorrelation

Front 125

Study of clips flow through the circulatory system is called

Back 125

Hemodynamics

Front 126

This type of flow is found mainly in arteries and has variable validities due to cardiac contradictions

Back 126

Pulsating flow

Front 127

This type of flow is found in the veins and changes velocity due to respiratory actions

Back 127

Phasic flow

Front 128

This type of flow is a constantly streaming st a steady velocity with no affect of the heart of respiration

Back 128

Steady flow

Front 129

What type of flow is predicted when Reynolds number is <1500

Back 129

Laminar flow

Front 130

Laminar flow can be described as _______ or ________

Back 130

Plug or parabolic

Front 131

What type of flow has all blood layers traveling at the same speed

Back 131

Plug flow

Front 132

What type of flow is slower on the outside (toward walls) and faster at the center

Back 132

Parabolic flow

Front 133

Parabolic flow is said to have a ________ profile

Back 133

Bullet

Front 134

What type of flow exhibits chaotic flow with vortices and eddies

Back 134

Turbulent flow

Front 135

Reynolds number greater than ______ will predict turbulent flow

Back 135

>2000

Front 136

This is a sound that is heard by the doctor during a physical exam when turbulent blood flow is present

Back 136

Bruit

Front 137

What is a thrill

Back 137

A palpable vibration over a turbulent area. Commonly felt over the anastomoses in a dialysis fistula

Front 138

What type of energy do moving blood cells possess

Back 138

Kinetic

Front 139

Kinetic energy

Back 139

Found in objects that are moving. Dependent on the objects mass and speed

Front 140

What type of energy is the main type of energy in the circulatory system

Back 140

Pressure

Front 141

Pressure energy

Back 141

Must overcome resistance for blood flow. PE has the potentiometer to do work. As the pressure energy increases above resistance, the PE is chance into kinetic energy

Front 142

What type of energy is related to the elevation of an object

Back 142

Gravitational

Front 143

Gravitation energy

Back 143

Is also potentiometer energy. As an object loses its elevation, it is turned into kinetic energy

Front 144

This term is measures in Poise and tells the thickness of a liquid

Back 144

Viscosity

Front 145

Hematocrit tells_______

Back 145

How thick the blood is

Front 146

As blood cells come in contact with vessel walls, some energy is converted into heat because of __________ energy loss

Back 146

Frictional

Front 147

This Tyler of energy loss occurs with pulsatilla flow, phasic flow, and flow through a stenosis

Back 147

Inertial

Front 148

Turbulent flow is expected_______ of a stenosis

Back 148

Down stream

Front 149

Bernoulli principle tells us that blood flow velocity increases in a stenosis and pressure ______

Back 149

Decreases

Front 150

A patient who is 🕰______ has the same hydrostatic pressure at every level

Back 150

Supine

Front 151

Hydrostatic pressure is relative to the heart level. Pressure at the level of the ears in the standing patient would be________ mmHg

Back 151

Negative

Front 152

This muscle moves up into the thorax during expiration and down into the abdomen during inhalation

Back 152

Diaphragm

Front 153

During this action, blood flow from the head and arm veins increases and blood return from the legs cease

Back 153

Inspiration

Front 154

During this action, blood return from the legs increases and blood return from the arms ceases

Back 154

Expiration

Front 155

What pressure is added to hydrostatic pressure to get measures pressure

Back 155

Circulatory pressure

Front 156

What lab test measures the viscosity of blood

Back 156

Hematocrit

Front 157

Hematocritu gives the % of blood that is made up of _______

Back 157

RBC's

Front 158

During expiration

Back 158

Pressure in thorax increases and abdominal pressure decreases

Front 159

During inspirstion

Back 159

Pressure in the thorax decreases and abdominal pressure increases

Front 160

If the heart is 0 mmHg, the ears would be -50 mmHg. Anything below the heart would be positive and increase towards the_______

Back 160

Ankles

Front 161

4 types of artifacts

Back 161

Resolution

Propagation

Attenuation

Doppler

Front 162

Resolution artifacts

Back 162

Axial/lateral

Slice thickness

Speckle/noise

Front 163

Propagation artifacts

Back 163

Reverberation

Ring down

Mirror

Shadowing

Multi path

Refraction

Lobe

Speed error

Range ambiguity

Front 164

Another name for ring down

Back 164

Comet tail

Front 165

Attenuation artifacts

Back 165

Shadowing

Edge shadowing

Enhancement

Focal banding

Front 166

PW and color Doppler artifacts

Back 166

Mirror/cross talk

Aliasing

Ghosting/clutter

Twinkle

Front 167

QA program goals

Back 167

Guarantee proper operation

Detect gradual changes

Minimize down time

Reduce non diagnostic exams

Reduce repeat scans

Front 168

Beam profiler

Back 168

Slice thickness phantom

Assesses effect of slice thickness on image accuracy and determines elevational resolution

Front 169

Tissue equivalent phantom

Back 169

Similar to soft tissue. Useful in evaluation of gray scale

Front 170

Small needle type structure with PZT attached to its end

Back 170

Hydrophone

Front 171

Small needle type structure with PZT attached to its end

Back 171

Hydrophone

Front 172

A sound wave can exert small, but measurable force in the object it strikes is known as

Back 172

Radiation firce

Front 173

Based on sound and light

Shadowing system called a schlieren

Back 173

Acoustic- optics

Front 174

Acoustic optics allows us to see the sago of a sound beam in a medium

Back 174

True

Front 175

Acoustic optics allows us to see the sago of a sound beam in a medium

Back 175

True

Front 176

_________ measures the total output power in a sound beam by observing absorption

Back 176

Calorimeter

Front 177

Tiny electric thermometer where absorbing material is placed within the sound beam to measure power of beam at specific location

Back 177

Thermocouple

Front 178

Tiny electric thermometer where absorbing material is placed within the sound beam to measure power of beam at specific location

Back 178

Thermocouple

Front 179

These crystals change color based on temperature and give insight to power of beam as energy changes to hear

Back 179

Liquid crystals

Front 180

Tiny electric thermometer where absorbing material is placed within the sound beam to measure power of beam at specific location

Back 180

Thermocouple

Front 181

These crystals change color based on temperature and give insight to power of beam as energy changes to hear

Back 181

Liquid crystals

Front 182

Mechanistic approach

Back 182

Searches for a relationship between cause and effect

Front 183

Tiny electric thermometer where absorbing material is placed within the sound beam to measure power of beam at specific location

Back 183

Thermocouple

Front 184

These crystals change color based on temperature and give insight to power of beam as energy changes to hear

Back 184

Liquid crystals

Front 185

Mechanistic approach

Back 185

Searches for a relationship between cause and effect

Front 186

Empirical approach

Back 186

Searches for the relationship between exposure and response

Front 187

Tiny electric thermometer where absorbing material is placed within the sound beam to measure power of beam at specific location

Back 187

Thermocouple

Front 188

These crystals change color based on temperature and give insight to power of beam as energy changes to hear

Back 188

Liquid crystals

Front 189

Mechanistic approach

Back 189

Searches for a relationship between cause and effect

Front 190

Empirical approach

Back 190

Searches for the relationship between exposure and response

Front 191

Three forms of thermal index (TI)

Back 191

TIS soft tissue thermal index

TIB bone thermal index

TIC cranial bone thermal index

Front 192

Each image is made up of multiple ___________, these are lines the sound pulses are sent down to create an image

Back 192

Scan lines

Front 193

A ________ consists of one PZT crystal and one wire connected back to the machine electronics

Back 193

Channel

Front 194

Linear array refers to

Back 194

Straight line

Front 195

Linear array refers to

Back 195

Straight line

Front 196

Annular array refers to

Back 196

Concentric circles

Front 197

Linear array refers to

Back 197

Straight line

Front 198

Annular array refers to

Back 198

Concentric circles

Front 199

Convex array refers to

Back 199

Curved or bowed line

Front 200

Mechanical transducer

Back 200

1 PZT disc shaped

Steering:mechanical

Focus: fixed

Shape: sector

Damaged: whole image gone

Front 201

Mechanical transducer

Back 201

1 PZT disc shaped

Steering:mechanical

Focus: fixed

Shape: sector

Damaged: whole image gone

Front 202

Linear phases transducer

Back 202

100-300 PZT, small and rectangular

Steering: electronic

Focus: electronic

Shape: sector

Damaged: erratic steering and focusing (not obvious)

Front 203

Mechanical transducer

Back 203

1 PZT disc shaped

Steering:mechanical

Focus: fixed

Shape: sector

Damaged: whole image gone

Front 204

Linear phases transducer

Back 204

100-300 PZT, small and rectangular

Steering: electronic

Focus: electronic

Shape: sector

Damaged: erratic steering and focusing (not obvious)

Front 205

When a sonographer uses _________, multiple sound beams with different foci are created

Back 205

Multi focus

Front 206

Annular phased array transducer

Back 206

Multiple ring shaped PZT

Steering: mechanical

Focus: electronic

Shape: sector

Damaged: band of dropout across sector @bottom

Front 207

Linear sequential array transducer

Back 207

120-250 PZT, larger and rectangular

Steering: electronic

Focus: electronic

Shape: rectangle

Damaged: band of drop out down image

Front 208

Combed or curvilinear array transducer

Back 208

120-250 PZT, rectangular

Steering: electronic

Focus: electronic

Shape: blunted sector

Damaged: band of dropout down image

Front 209

Combed or curvilinear array transducer

Back 209

120-250 PZT, rectangular

Steering: electronic

Focus: electronic

Shape: blunted sector

Damaged: band of dropout down image

Front 210

Vector or virtual array transducer

Back 210

120-350 PZT, rectangular

Steering: electronic

Focus: electronic

Shape: trapezoidal

Damaged: need large group to show

Front 211

Formula for PD

Back 211

PD= # cycles x period

Both increases in cycles and period increase PD

Front 212

Formula for PD

Back 212

PD= # cycles x period

Both increases in cycles and period increase PD

Front 213

Formula for SPL

Back 213

SPL= # cycles x wavelength

Axial resolution= 1/2 SPL

Front 214

Shorter pulse duration equals better___________

Back 214

Axial resolution

Front 215

________ affects frame rate and temporal resolution

Back 215

PRF

Front 216

Duty factor formula

Back 216

DF%= PD/PRP

Front 217

Six major components of pulses echo

Back 217

Transducer

Pulser or beam former

Receiver

Display

Storage

Master synchronizer

Front 218

Six major components of pulses echo

Back 218

Transducer

Pulser or beam former

Receiver

Display

Storage

Master synchronizer

Front 219

What type or transducer requires a beam former

Back 219

Array

Front 220

What is a descriptor or pulser

Back 220

Output power

Front 221

Protects the receiver from strong electrical energy sent out during transmission

Back 221

Switch

Front 222

______________ aka ____________ every returning signal is made larger or smaller

Back 222

Amplification, Receiver gain

Front 223

______________ aka ____________ every returning signal is made larger or smaller

Back 223

Amplification, Receiver gain

Front 224

________ adjusts the picture to account for attenuation

Back 224

Compensation (TGC)

Front 225

___________ or __________ keeps electrical signals within the accuracy range of the system

Back 225

Compression, dynamic range

Front 226

Second compression keeps gray scale within detectable range for _________

Back 226

Humans, different than first compression

Front 227

__________ changes the electrical signal into information that can be displayed on a monitor

Back 227

Demodulation

Front 228

__________ changes the electrical signal into information that can be displayed on a monitor

Back 228

Demodulation

Front 229

Demodulation inviles

Back 229

Rectification and smoothing or enveloping

Front 230

Machine and sonographer decide if very low signals are important or extra noise

Back 230

Reject

Front 231

Imagine transducer doesn't emit a pure single freuency

Back 231

Bandwidth

Front 232

Bandwidth is the difference between the _________ and _________ frequency

Back 232

Highest and lowest

Front 233

Bandwidth: lower frequency means

Back 233

Longer wavelength

Greater penetration

Front 234

Bandwidth: lower frequency means

Back 234

Longer wavelength

Greater penetration

Front 235

Bandwidth: high frequency means

Back 235

Shorter wavelength

Better axial resolution

Front 236

Q factor= pure clean sound

Back 236

True

Front 237

Q factor= pure clean sound

Back 237

True

Front 238

Short pulses= low Q factor and

Back 238

High quality images