ch 12 & 13

23問 • 1年前

問題一覧

The length of a pulse does not directly influence the temporal resolution.

True

Two imaging systems produce acoustic pulses; one pulse is 0.4 psec long and the other is 0.2 psec long. Which is most likely to provide the best temporal resolution?

cannot be determined

An ultrasound system with a shorter pulse repetition period (PRP) will have better temporal resolution than a system with a longer PRP.

True

A sonographer reduced the sector size from 90 degrees to 30 degrees. Frame rate, however, did not change. What else happened?

multi-focus was turned on

Mechanical scanning produces pictures that are similar in shape to linear phased array images. .

True

Which of the following is best described as mechanically steered and multi-focus?

annular phased array transducer

A linear sequential array transducer has 128 crystals. How many of these crystals are fired to create a single sound beam?

a small group

A machine that displays A-mode and two-dimensional images is called a duplex scanner.

False

Side lobes degrade axial resolution.

False

Side lobes degrade lateral resolution.

True

Mechanical scanning produces scan lines that separate or diverge with greater depth.

True

The firing delay patterns of a linear phased array transducer

focus the sound beam during transmission

Which of the following forms of resolution improve when frame rate increases?

temporal

Which of the following is consistent with improved temporal resolution?

higher frame rate

A sonographer adjusts an ultrasound scan to double the depth of view from 5 cm to 10 cm. If the frame rate remains the same, which one of the following also occurs?

narrower sector

A sonographer adjusts an ultrasound machine to change the sector size from 90 to 45 degrees. Nothing else changes. What happens to the frame rate?

it is doubled

A sonographer adjusts an ultrasound system to change the sector size from 90 to 45 degrees. The frame rate was unchanged. What else must have happened?

line density was doubled

A sonographer reduces the sector angle from 90 degrees to 30 degrees. At the same time, the ultrasound system automatically increases the line density from 1 line per degree to 2 lines per degree. No other changes are made. What will happen to the frame rate?

increases

A sonographer reduces the sector angle from 90 degrees to 30 degrees. At the same time, the ultrasound system automatically increases the line density from 1 line per degree to 3 lines per degree. No other changes are made. What will happen to temporal resolution?

remains unchanged

What is the time needed to make a single image if the frame rate of an ultrasound system is 20 Hz?

0.05 s

Which of the following will have no effect upon temporal resolution? increasing imaging depth Which of the following will have no effect upon temporal resolution? increasing imaging depth

increasing transducer frequency

The effect on the image with a damaged crystal of the linear phased array

Erratic steering, focusing

A sonographer adjusts the sector size from 90 degrees to 45 degrees. if nothing else is changed the frame rate is unchanged, what else might have happened

Line density was doubled

ch 6 AP

ユーザ名非公開 · 20問 · 1年前

ch 6 AP