Chapter 8

Question 1

True or False. Any time a vessel is without color, the first thing to do is check the angle between flow and sound.

Answer 1

True

Question 2

True or False: For color to appear in the vessel, an angle of 90 degrees must be created between the direction of flow and the direction of the sound beam.

Answer 2

False

Question 3

True or False: When the color gain is set to an inappropriately low level, all color will disappear in the image

Answer 3

True

Question 4

List potential causes of artifact in diagnostic imaging.

Answer 4

Violation of Assumption, Equipment Malfunction, Physics of Ultrasound, and Operator Error

Question 5

Six distinct, equally spaced reflections appear on an image at ever increasing depths. What type of artifact is this?

Answer 5

Reverberation

Question 6

What type of situation will commonly produce reverberation artifact?

Answer 6

When the medium has a very high propagation speed or from a resonance, or vibration, of a small structure such as a gas bubble.

Question 7

Where are shadowing artifacts commonly seen on an acoustic scan?

Answer 7

In the Tissue above the shadow (deep reflecting surfaces)

Question 8

How is shadowing artifact expressed?

Answer 8

They express as the same color as the background

Question 9

What causes enhancement artifact?

Answer 9

Appear beneath tissues with abnormally low attenuation

Question 10

When enhancement occurs, where does it appear on the image?

Answer 10

Hyperechoic regions are brighter and the same color as the foreground (echoes) of the image.

Opposite of shadowing artifact

Question 11

What process causes mirror image artifact?

Answer 11

Created when sound reflects off a strong reflector and is redirected toward a second structure. This is what causes the “replica”

Question 12

Where is a mirror image artifact located?

Answer 12

Located deeper than the real structure

Question 13

What type of artifact is created by sound moving through a medium with a propagation speed less than soft tissue?

Answer 13

It produces, Speed Error

Question 14

While imaging a test object, an ultrasound system displays one image 1.8 cm deeper than another. Upon measuring the test object, it is found that it is actually 2.0 cm deeper. What conclusion can be drawn from this?

Answer 14

That there is a range error artifact

Question 15

What causes side lobe artifact?

Answer 15

Lobes created by a mechanical transducer are known as side lobes

Question 16

Grating lobes are most common with which type of transducer technology?

Answer 16

Array transducers

Question 17

True or false? Grating lobes are attributed only to array transducers.

Answer 17

True

Question 18

What assumption is violated when a refracted sound wave is processed?

Answer 18

Sound travels in a straight line, is invalid

Question 19

With standard diagnostic imaging instrumentation, which has the higher numerical value?
A. axial resolution
B. lateral resolution
C. elevational resolution
D. No answer text provided.

Answer 19

D

Question 20

Axial resolution artifacts are due to which of the following?
A. multiple reflections
B. beam width
C. attenuation
D. pulse length

Answer 20

D

Question 21

The lateral resolution of four ultrasound systems appear below. Which will produce the finest quality picture?
A. 2 cm
B. 4 mm
C. 6 mm
D. 8 hm

Answer 21

B

Question 22

True or false? All artifacts are errors in imaging that do not represent the true anatomy of the imaged organ. Therefore, they are all undesirable and should be eliminated if possible.

Answer 22

False

Question 22

In diagnostic imaging, how does multipath artifact affect the image?

Answer 22

The transmit path length differs from the return path length which often results in subtle, nonspecific changes that cannot be specifically identified on the image.

Question 23

Which artifact is not related to the unexpected reflection of an acoustic wave?
A. multipath
B. comet tail
C. reverberation
D. lateral resolution

Answer 23

D

Question 24

What is the cause of acoustic speckle?

Answer 24

Acoustic speckle is produced by the constructive and destructive interference of small acoustic waves reflected from small reflectors in the near field

Question 25

Ultrasound systems are designed to automatically ________.

Answer 25

display all reflections on a line corresponding to the main axis of the sound beam, regardless of refraction

Question 26

Which of the following determines the spatial resolution of an image on a monitor?
A. strength of the electron beam
B. form of phosphor coating of the screen
C. number of lines of the monitor’s display
D. the pulse duration

Answer 26

C