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Spring: Physics > Study guide Ch 21,22,23:test 4 > Flashcards

Study guide Ch 21,22,23:test 4 Flashcards

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1
Q

What describes portions of an image that are brighter than surrounding tissues or tissues that appear brighter than normal?

A

hyperechoic

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2
Q

What describes images that are not as bright as surrounding tissues or appear less bright than normal?

A

hypoechoic

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3
Q

What describes a structure without echoes?

A

anechoic

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4
Q

What describes a tissue or structure that has a similar echo throughout?

A

isoechoic

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5
Q

What describes a tissue displaying a variety of different echogenic characteristics?

A

heterogeneous

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6
Q

What are considered errors in imaging?

A

reverbation, comet tail, shadow & edge shadow, enhancement & focal enhancement, mirror image & cross talk, curved & oblique reflectors, temporal resolution, spatial resolution, speed error, lobes: side & grating lobes, refraction, slice thickness, lateral resolution, axial resolution, multipath, range ambiguity, noise: speckle & clutter

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7
Q

Equipment malfunction and design, the physics of ultrasound, and operator error: what are these called?

A

causes of artifacts

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8
Q

Multiple, equally spaced, parallel lines: what does this describe?

A

characteristics of reverberation

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9
Q

Which artifact is unrelated to the dimensions of an ultrasound pulse?

A

refraction

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10
Q

Which artifact produces an image with an incorrect number of reflectors side by side?

A

side lobes

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11
Q

What does not result in the placement of too many echoes on the image?

A

shadowing

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12
Q

What does not result from multiple reflections?

A

enhancement

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13
Q

Two distinct reflections are observed on an image, but they actually arise from a single anatomic structure. The artifact is positioned deeper than the correct reflection. What is the most likely cause of this artifact?

A

mirror image

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14
Q

Two reflections, side by side, only one is real. What is most likely the cause of this artifact?

A

refraction

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15
Q

Which artifacts create one reflection on an image from two closely spaced reflectors?

A

axial resolution

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16
Q

When the beam dimention is greater than the reflector size, what type of artifact can occur?

A
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17
Q

What are lobes created by array transducers called?

A

grating lobes

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18
Q

What methods can be used to eliminate lobe artifacts?

A

subdicing and apodization

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19
Q

A single, solid, hyperechoic line parallel to the sound beam with no spaces in the echogenic line is what artifact?

A

comet tail

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20
Q

What artifact occurs when the beam is unable to pass through a structure?

A

shadowing

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21
Q

Refraction at the end of a circular structure can cause what artifact?

A

edge shadow (shadowing by refraction)

22
Q

What artifact occurs when there is too much gain in the focal zone?

A

focal enhancement

23
Q

What artifact occurs when the medium to which the sound travels has a lower attenuation rate than soft tissue?

A

speed error

24
Q

Which artifact occurs when you see reflectors at incorrect depths?

A

speed error

25
Q

When propagation speed is greater than 1,540 m/s, the reflector will be placed to what on the display?

A

reflectors are too shallow on the image

26
Q

Grading lobes are caused by which type of transducer?

A

array transducers

27
Q

What artifact can be cured by lowering the PRF?

A

range ambiguity

28
Q

Which artifact is only found with doppler?

A

cross talk

29
Q

A grainy appearance not directly from tissues created by interference is called what?

A

speckle

30
Q

If the media in which the ultrasound travels doesn’t propagate at 1,540 m/s, then the assumed relationship between time and distance is invalid. What artifact occurs?

A

speed error (range error artifact)

31
Q

Propagation speed errors appear as a what?

A

a step off

32
Q

What are errors in imaging?

A

not real

not seen on the image

incorrect shape or size

incorrect position

incorrect brightness

33
Q

What are causes of artifacts?

A

violation of assumptions

equipment malfunction or poor design

the physics of ultrasound

operator error

34
Q

What are the two causes for crosstalk?

A

Doppler gain is set too high

incident angle is near 90° between the sound beam and the flow direction, when flow is at the beam’s focus

35
Q

What is color flash also referred to as?

A
36
Q

What are wall filters used to reject?

A
37
Q

If the path to a reflector is of a different length than the returning path, the reflector will be in an incorrect position, it results in general image degradation. What artifact is it?

A

speed error

38
Q

What produces shadowing?

A

attenuation is higher in the tissues above the shadow

39
Q

Where does enhancement appear on an image?

A

beneath tissues with abnormally low attenuation

40
Q

Which transducer may have poor elevational resolution?

A
41
Q

What term is defined by avoidance of unnecessary risk, harm or needless injury?

A

nonmaleficence

42
Q

What provides the basis for an informed consent?

A

autonomy

43
Q

When can a patient revoke consent?

A

at any time

44
Q

What is the first action when a sonographer enters a patient’s room?

A

intorduce themselves to the patient

45
Q

What is the study between a worker and their environment called?

A

ergonomics

46
Q

What standard is best used in a quality assurance program?

A

objective

47
Q

All of the following are characteristics of a tissue equilavent phantom except:

A

density similar to that of soft tissue

48
Q

What form of resolution is evaluated by measuring the width of reflections arising from small, point targets?

A

lateral resolution

49
Q

What form of resolution is evaluated by visualizing closely spaced pins that are parallel to the sound beam’s main axis?

A

axial resolution

50
Q

At what interval should quality assurance evaluations be performed?

A

routinely

Spring: Physics (10 decks)

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