Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Ultrasound Physics > Chapter 20, 21, 22 Bioeffects & Quality Assurance > Flashcards

Chapter 20, 21, 22 Bioeffects & Quality Assurance Flashcards

0
Q

Name the causes of Artifacts

A 
Assumption violation
	~prop velocity, resistence, beam change
Physics happens
	refraction, grading lobes, specular reflection
Operator error
	~Oblique angle, distance to ROI
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

Name the artifact reflection errors.

A 
Reflection not real
Reflection missing from image
Incorrect shape
Incorrect location
Incorrect brightness
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are some Assumptions?

A

‘Sound traveling in a straight line’
The sound beam will travel straight back’
‘Sound travels at a constant speed in tissues (1540m/s
The reflection travel from the main beam axis only
Amount of reflection related to tissue characteristics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is Reverbration?

A

Sound beam bouncing between 2 strong reflectors, bounce between them like a ping-pong ball. This creates multiple parallel line echos one posterior to the other, but only 1 or 2 of the lines are real. This is seen in such places as the diaphragm or the gallblader.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is comet tail?

A

it is a type of reverbertion artifact, caused by 2 closely placed reflectors, appearing as a echogenic line reaching posteriorly “reverberation as a solid line stretching anterior to posterior”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Give some examples of comet tail.

A

Tissue,
gas
lung
Comet tail is caused by natural tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Ring Down what is it?

A

Another type of reverberation artifact, closely resembling comet tail, only is caused by abnormal objects not normal considered part of the body, with a distinct base on the structure image.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are some structures that cause Ring down?

A
  • Calcified structures, -surgical tips,

- needle tip

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Shadowing, what causes it?

A

A highly attenuating structure (shows up as something very echogenic on US) such as bone or stones, causing a shadow posterior to it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How can shadowing be helpfule?

A

Helps characterize a tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is edge shadow?

A

Refraction causing a decrease in beam intensity, it normally happens when an echo hits the edge of a curved object, causing hypoechoic regions posterior along the edge of a refractor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is enhancement?

A

It is a hyperechoic area caused by being behind a structure with low attenuation ( not cause by a difference in propagational speed ) it is the opposite of shadowing and aluminate deeper structures. Examples: GB, cystic structures Adipose, UB.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is Focal Banding?

A

It looks like TGCs are off, and is caused by the focusing of the beam, making a brighter focus area because of reflected echoes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Mirror image what is it?

A

The beam bounces off structures and images area outside the beam’s path, and received as signal, creating a false structure, a little deeper then the true structure. Happen in 2D and Doppler

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Speed Error is …?

A

Caused by echoes not traveling the assumed speed of 1540m/sec. This makes structures appear at the wrong depth, can be seen in a step-down in image.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens when the speed error is higher then the assumed speed?

A

⬇️ In round trip time = Image of structure is too shallow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens when the speed error is lower then the assumed speed?

A

⬆️ In roundtrip time = Image of structure to deep.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are lobe artifacts?

A

Far lateral aspects of the beam hits a strong reflecture, but returning echo is weak but strong enough to registry resulting in a second copy of the reflector right beside it, requiring multiple angles to distinguish real one.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How do we correct lobe artifact?

by….

A

Subdicing: A large element (crystals) divied into smaller elements

Apodization: reducing the voltage to the far lateral crystals on a transducer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What kind of artifact does Refraction cause?

A

Second copy of reflector next to the true reflecture.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What causes Slice thickness artifacts?

A

Happens when the object is thinner then our beam thickness (elevation). this causes small areas that are suppose to be anechoic to be filled in, such as the neck of GB, small cysts, fetal N/L.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What kink of artifact is associated with lateral resolution?

A

Unable to see two objects as seporate, espieshally in far field.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What kink of artifact is associated with lateral resolution?

A

Unable to distingish structure anterior/posterior to eachother, seeing two structures as one big object.

23
Q

What is multipath?

A

Sound reflecting off of multiple reflectores before returning to transducer, the effect veries due to reflector and beam path

24
What defines a curved/oblique reflectors?
This is what causes edge shadowing, echoes at the edge of the artifact do not come back, it may not be noticable until resolved.
25
What is Speckle?
Caused by the constructive and destructive interference of sound waves making irregular tissue texture - seen as course tissue, such as in thyroid - can reduce/eliminate What is quality assurance? Routine, periodic, regular evaluation of ultrasound equipment to ensure optimal image quality Requirements for quality assurance? Assess system components Repair problems Preventative maintenance Record keeping
26
Goals of Quality assurance?
``` Proper operation of equipment Detect gradual changes Minimize downtime (unused machines don’t make money!) Reduce non-diagnostic exams Reduce repeat scans ```
27
Tools of the trade?
AIUM 100mm test object Tissue phantom Doppler phantom Beam profile/thickness phantom
28
What is a AIUM Phntom?
Used to calabrate the US' Resolution with predetermined distenced objects, set in a 'V' pattern, getting closer and closer together unit utile US precieve them as one. Registration: are the determine weather a beam is symetricle/equal by equally spaced pins, to measure with calapers Contrast/tissue: to determined the gray scale of mechien is suffient.
29
What are ways AIUM 100mm test obects test, luid, speed and pin orientation?
``` Fluid/ “tissue” with pins or string at certain distances No attenuation Developed for A mode and static scanning Speed of transmission exactly 1540m/s SPI- Know which face being scanned! Pin orientation Parallel to beam = AR “V” across beam Perpendicular to beam = LR “V” down beam Dead Zone = area proximal to transducer ```
30
HOW DOES TISSUE PHANTOMS WORK and what do they evaluat?
They are used for registrasion and gray scale charecteriscics - attenuation - scatters beam - mimics real life applications
31
How does the doppler phantom evaluate?
By vibrating a string, moving belt or pump to creat flow.
32
What is Sensitivity?
Ability of system to display low-level echoes Minimum- assessing weakest echo displayed -Flat TGCs, increasing gain until low level FF rod displayed Normal- assessing all echoes in phantom -Power, 2D and TGCs increased until all echoes seen Maximum- assessing max visualization depth -All settings at max, increase depth to maximum displayed
33
What does the Calorimeter do?
Measures total power of sound beam through absorbtion
34
Thermocouple?
Cine thermometer that measures the tempreture in the beam, to alert if there is a posibility for bioeffects.
35
What are liquid Crystals?
Thermal active crystals which changes color like mood rings in responce to temprature changes.
36
What must we consider Conserning bioeffects?
-Benifits must outweigh the risks
37
What is Dosimetry?
Study of measuring beam characteristics that have the potential to produce bioeffects: - In Vivo- resurch conducted within living tissue - In Vitro resurch conducted outside the living tissue
38
What is there to be weary of with in-vitro bioeffects?
bioeffects that it claims happen should be taken with a grain of rice
39
What are the 2 approches to bioefect resurch?
Mechanistic approach- searches for relationships between cause and effect Eating ice cream makes NYs violent Empirical approach-searches for a relationship between exposure and response Lets feed NYs ice cream and see what happens
40
What is thermal Bioeffects?
Increase in tissue tempreture caused by attenuation, which alters cell activity.
41
What are Cavitation bioeffects?
⬆️ in gaseous bubbles ithin tissues
42
What is the thermal index?
``` Is a unitless number that prodicts tempreure increases due to bioeffects inside tissues: TI 1 = 1 degree temp increase expected TIS= Soft tissue TIB= bone TIC = Cranial Bone ```
43
How are Mechanistic and empiricle resurch approach thermal findings?
Mechanistic- There is a relationship between exposure and increases in tissue temperature Empirical- Prolonged temp elevation can damage tissue Temp elevation related to output and tissue characteristics 2-4 degree rise in testicular temp can cause infertility
44
According to Empirical reaserch what tissue is greatly effected by Temp. change?
Fetal tissues are less tolerant that adult tissues. Many fetal tissue defects have resulted from increased temperatures. None have been observed at 39 degrees or less Fetal bone absorbs a high amount of acoustic energy.
45
What is Microstreaming?
Is the circulation of fluid with in tissues due to temp. change, which can lead to cavitation. The fluid around cells puts shear stress on surrounding cells.
46
What is considered Stable Cavitation?
This has a low MI level, where bubbles shrink and expand, but due not bust and cause tissue damage. These bubbles absorbs acoustic energy.
47
What is transient Cavitasion?
This is with a Higher MI, where the bubbles expand and burst causing tissue damage, and makes a shock wave that exerts presser on neighboring cells.
48
What does ALARA stand for?
As Low As Reasonably Achievble.
49
What is Coded Excitation?
Coded Excitation- digital codes used by beam former to alter pulse duration, results in multiple frequencies within one pulse, produces distinct/recognizable pulses - Improves Signal to Noise - Multi Fs used on other processing techinques
50
What is frequency compounding?
Compares data from two mini bandwidth taken from the one original returning bandwth, allow the US to multitask. - this reduces speckle - improves contrast resolution
51
What is Persistence/frame averaging?
Averages frames per time, both Color and 2D Short term events can get removed, long term events can be exaggerated •Newer frames given priority to older frames
52
What is color priority?
Displays pixel with color info vs 2D/brightness info when increased -Compromised spatial resolution -No effect on temporal resolution Improves color at the expence of spatial resolution
53
What is compound imaging?
areas scanned at slightly different angles and data is averaged together - Reduced reverberation artifact - Improved signal to noise
54
Spatial Averaging?
Breaks up larger images up into smaller sections and averages areas of missing data with the neighboring areas -reduces noise but no improvement to signal detection.
55
What is Parallel Processing?
one transmit beam out and two smaller beams are processed at the same time from big beam. transmit together and process separately. It saves time and so improves temporal resolution -done automatically (like cutting a carrot in half and cutting them up side by side to cut it faster.)
56
What is Interpolation?
it uses data from other amplitudes to fill in missing data, ⬆️ # of scan lines - degrades temporal resolution - but goo for static images needing high detail

Ultrasound Physics (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions