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

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Flashcards in Study guide Ch 21,22,23:test 4 Deck (50):
1

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

hyperechoic

2

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

hypoechoic

3

What describes a structure without echoes?

anechoic

4

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

isoechoic

5

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

heterogeneous

6

What are considered errors in imaging?

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

7

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

causes of artifacts

8

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

characteristics of reverberation

9

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

refraction

10

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

side lobes

11

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

shadowing

12

What does not result from multiple reflections?

enhancement

13

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?

mirror image

14

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

refraction

15

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

axial resolution

16

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

17

What are lobes created by array transducers called?

grating lobes

18

What methods can be used to eliminate lobe artifacts?

subdicing and apodization

19

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

comet tail

20

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

shadowing

21

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

edge shadow (shadowing by refraction)

22

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

focal enhancement

23

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

speed error

24

Which artifact occurs when you see reflectors at incorrect depths?

speed error

25

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

reflectors are too shallow on the image

26

Grading lobes are caused by which type of transducer?

array transducers

27

What artifact can be cured by lowering the PRF?

range ambiguity

28

Which artifact is only found with doppler?

cross talk

29

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

speckle

30

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?

speed error (range error artifact)

31

Propagation speed errors appear as a what?

a step off

32

What are errors in imaging?

not real

not seen on the image

incorrect shape or size

incorrect position

incorrect brightness

 

33

What are causes of artifacts?

violation of assumptions

equipment malfunction or poor design

the physics of ultrasound

operator error

34

What are the two causes for crosstalk?

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

What is color flash also referred to as?

36

What are wall filters used to reject?

37

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?

speed error

38

What produces shadowing?

attenuation is higher in the tissues above the shadow

39

Where does enhancement appear on an image?

beneath tissues with abnormally low attenuation

40

Which transducer may have poor elevational resolution?

41

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

nonmaleficence

42

What provides the basis for an informed consent?

autonomy

43

When can a patient revoke consent?

at any time

44

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

intorduce themselves to the patient

45

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

ergonomics

46

What standard is best used in a quality assurance program?

objective

47

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

density similar to that of soft tissue

48

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

lateral resolution

49

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

axial resolution

50

At what interval should quality assurance evaluations be performed?

routinely