ch 4

84問 • 1年前

問題一覧

Spatial Pulse Length (SPL) is the product of a. velocity and PRP b. frequency and period c. propagation speed and PRF d. wavelength and cycles per pulse e. wavelength and velocity

wavelength and cycles per pulse

SPL is determined by

Source and medium

Spatial pulse length is

Wavelength X number of cycles in pulse

What happens to SPL if depth of view increases using the same transducer?

Remains the same

If frequency increases, the spatial pulse length

Decreases

Pulse A is from a 5 MHz transducer and pulse B is from a 10 MHz transducer. Both pulses have 4 cycles per pulse.

Pulse A will have greater SPL

If you increase the depth of view from 2 cm to 3 cm, the SPL

Does not change

Which pulse has a longer spatial pulse length?

cannot be determined

PRP is defined as

The pulse transmit or “on” time plus the pulse listening or “off” time

The number of pulses occurring in 1 sec is called the

Pulse repetition frequency

Two waves can have identical Pulse Repetition Frequencies, even if their frequencies are different.

True

When you change the PRF you are changing

The number of pulses per second

The range of PRF used in diagnostic ultrasound is

1 to 10 kHz

PRP and PRF can be changed by

altering depth of view

If the depth of view increases, the PRF

Decreases

If the PRF increases, the PRP

Decreases

Pulse Repetition Period is the reciprocal of Pulse Duration

False

The PRF of a 5 MHz transducer is greater than the PRF of a 2.5 MHz transducer.

True

PRF depends on

Source of the sound wave/transducer

What is the value of the duty cycle for continuous wave (CW) U/S?

100 %

In pulsed ultrasound, the maximum value of the duty factor is

Less than 100%

Duty factor depends on the frequency of the transducer

false

Duty factor is determined by

The transducer only

If the PRF decreases, the duty factor

Decreases

When the spatial pulse length increases, the duty factor

Increases

Two pulses are created by different transducers and both have the same frequency, the pulse containing more cycles has

Longer pulse duration

Duty factor can be changed by the sonographer.

True

The units for duty factor are

A ratio without units

Which is the highest intensity?

SPTP

What are the units of intensity?

watts/cm squared

Intensity is equal to

Power/ area

Intensities are important because

Bioeffects on the tissue being scanned

Temporal intensity is

The beam intensity during the transmitting time

Spatial intensity is

The beam intensity across the area being scanned

The beam uniformity coefficient describes

The spread of a beam in space (SP/SA factor)

The spatial intensity is usually highest at

The center of the beam

Which of the following will results in a decrease in beam intensity?

Increasing beam area

Power divided by beam areas is equal to

Intensity

Pulse duration is equal to

Period X number of cycles in pulse

Pulse duration is determined by

Source

A sonographer can adjust the duration of an acoustic pulse since it depends on the maximum imaging depth.

False

The units of pulse duration are units of

Time

If the depth of view increases, the pulse duration

Remains unchanged

Pulses from a 2.5 MHz transducer and a 5 MHz transducer each have 3 cycles per pulse. The pulse from the 2.5 MHz transducer has

longer pulse duration

A sonographer can adjust the pulse duration by

None of the above

Which of the following is determined by both source and medium?

wavelength

Which of the following frequencies is closest to the lower limit of iltrasound

25,000Hz

Sound can be described as

cyclical oscillation within a set of variables

Which waves are audible

28Hz

In order to be identified as ultrasound, the frequency of a wave must be greater than

20kHz

Which of these waves is most useful in diagnostic sonography

4MHz

The frequency of a transducer is 25,000,000 cycles per second. This can be written as

25MHz

All of the following are acoustic variables, except

power

Which parameter of the medium has the most effect on the velocity of sound in the medium?

bulk modulus of the medium

Constructive interference has the effect of ________ the amplitude of a wave

increasing

The interaction of echos that causes reinforcement rather than cancellation is known as

constructive interference

Wavelength depends on which two factors ?

frequency and propagation

Which of the following waves has the longest period

6Hz

Of the four waves whose frequencies are listed below which has the shortest

12kHz

If the frequency of an U/S wave is doubled what happens to the period

halves

If the frequency is 1MHz, what is the period

1 mircosec

As the frequency of an acoustic variable increases the wavelength

decreased

As the sound wave travels through soft tissue what happens to the frequency

it is not affected

As sound propagations through soft tissue the ampltitude

decrease proportional to distance

Intensity and power are related to amplitude by

proportional to amplitude squared

If the amplitude is doubled the intensity is

increased 4 times

If beam area is reduced by half and the power stays the same the intensity

doubles

The relative measurement of intensity based on the logarithmic scale has units of

decibles

The normal range of intensities used in Doppler ultrasound is

0.2 to 400 W/cm2

The wave propagates through the tissue the amplitude

decreases

With a 2 MHz transducer the wavelength in soft tissue is approximately

0.75 mm

As the frequency of the wave increases the wavelength will

decrease

The wavelength of the 3MHz transducer is shorter than the 6 MHz transducer

false

What is the wavelength of the 3 MHz transducer is shorter then the 6 MHz

false

What is the wavelength of 3MHz sound in soft tissue

0.51 mm

Image quality is affected by wavelength

true

If the frequency increases wavelength

decrease

The relationship between frequency and wave length is

inverse

Which pulse has a longer wavelength

from a 2 MHz

The number of wavelength passing a given point in a single second is called

frequency

Stiffness of a medium is the opposite of its

compressibility

When the elasticity of a medium is high the _____ is high

compressibility

The term bulk modulus is related to which quality

stiffness

The propagation speed used for soft tissue is

an average based on the usual percentages of each type of tissue

ch 6 AP

ch 6 AP

ch 9

ch 9

ch 11

ch 11

ch 16

ch 16

ch 12

ch 12

ch 13

ch 13

ch 14

ch 14

ch 17

ch 17

ch 19 (1)

ch 19 (1)

ch 15

ch 15

ch 9,10,11

ch 9,10,11

ch 12 & 13

ch 12 & 13

ch 14&15

ch 14&15

9-17

9-17

ch18

ch18

ch19-20

ch19-20

ch21-22

ch21-22

問題一覧

Spatial Pulse Length (SPL) is the product of a. velocity and PRP b. frequency and period c. propagation speed and PRF d. wavelength and cycles per pulse e. wavelength and velocity

wavelength and cycles per pulse

SPL is determined by

Source and medium

Spatial pulse length is

Wavelength X number of cycles in pulse

What happens to SPL if depth of view increases using the same transducer?

Remains the same

If frequency increases, the spatial pulse length

Decreases

Pulse A is from a 5 MHz transducer and pulse B is from a 10 MHz transducer. Both pulses have 4 cycles per pulse.

Pulse A will have greater SPL

If you increase the depth of view from 2 cm to 3 cm, the SPL

Does not change

Which pulse has a longer spatial pulse length?

cannot be determined

PRP is defined as

The pulse transmit or “on” time plus the pulse listening or “off” time

The number of pulses occurring in 1 sec is called the

Pulse repetition frequency

Two waves can have identical Pulse Repetition Frequencies, even if their frequencies are different.

True

When you change the PRF you are changing

The number of pulses per second

The range of PRF used in diagnostic ultrasound is

1 to 10 kHz

PRP and PRF can be changed by

altering depth of view

If the depth of view increases, the PRF

Decreases

If the PRF increases, the PRP

Decreases

Pulse Repetition Period is the reciprocal of Pulse Duration

False

The PRF of a 5 MHz transducer is greater than the PRF of a 2.5 MHz transducer.

True

PRF depends on

Source of the sound wave/transducer

What is the value of the duty cycle for continuous wave (CW) U/S?

100 %

In pulsed ultrasound, the maximum value of the duty factor is

Less than 100%

Duty factor depends on the frequency of the transducer

false

Duty factor is determined by

The transducer only

If the PRF decreases, the duty factor

Decreases

When the spatial pulse length increases, the duty factor

Increases

Two pulses are created by different transducers and both have the same frequency, the pulse containing more cycles has

Longer pulse duration

Duty factor can be changed by the sonographer.

True

The units for duty factor are

A ratio without units

Which is the highest intensity?

SPTP

What are the units of intensity?

watts/cm squared

Intensity is equal to

Power/ area

Intensities are important because

Bioeffects on the tissue being scanned

Temporal intensity is

The beam intensity during the transmitting time

Spatial intensity is

The beam intensity across the area being scanned

The beam uniformity coefficient describes

The spread of a beam in space (SP/SA factor)

The spatial intensity is usually highest at

The center of the beam

Which of the following will results in a decrease in beam intensity?

Increasing beam area

Power divided by beam areas is equal to

Intensity

Pulse duration is equal to

Period X number of cycles in pulse

Pulse duration is determined by

Source

A sonographer can adjust the duration of an acoustic pulse since it depends on the maximum imaging depth.

False

The units of pulse duration are units of

Time

If the depth of view increases, the pulse duration

Remains unchanged

Pulses from a 2.5 MHz transducer and a 5 MHz transducer each have 3 cycles per pulse. The pulse from the 2.5 MHz transducer has

longer pulse duration

A sonographer can adjust the pulse duration by

None of the above

Which of the following is determined by both source and medium?

wavelength

Which of the following frequencies is closest to the lower limit of iltrasound

25,000Hz

Sound can be described as

cyclical oscillation within a set of variables

Which waves are audible

28Hz

In order to be identified as ultrasound, the frequency of a wave must be greater than

20kHz

Which of these waves is most useful in diagnostic sonography

4MHz

The frequency of a transducer is 25,000,000 cycles per second. This can be written as

25MHz

All of the following are acoustic variables, except

power

Which parameter of the medium has the most effect on the velocity of sound in the medium?

bulk modulus of the medium

Constructive interference has the effect of ________ the amplitude of a wave

increasing

The interaction of echos that causes reinforcement rather than cancellation is known as

constructive interference

Wavelength depends on which two factors ?

frequency and propagation

Which of the following waves has the longest period

6Hz

Of the four waves whose frequencies are listed below which has the shortest

12kHz

If the frequency of an U/S wave is doubled what happens to the period

halves

If the frequency is 1MHz, what is the period

1 mircosec

As the frequency of an acoustic variable increases the wavelength

decreased

As the sound wave travels through soft tissue what happens to the frequency

it is not affected

As sound propagations through soft tissue the ampltitude

decrease proportional to distance

Intensity and power are related to amplitude by

proportional to amplitude squared

If the amplitude is doubled the intensity is

increased 4 times

If beam area is reduced by half and the power stays the same the intensity

doubles

The relative measurement of intensity based on the logarithmic scale has units of

decibles

The normal range of intensities used in Doppler ultrasound is

0.2 to 400 W/cm2

The wave propagates through the tissue the amplitude

decreases

With a 2 MHz transducer the wavelength in soft tissue is approximately

0.75 mm

As the frequency of the wave increases the wavelength will

decrease

The wavelength of the 3MHz transducer is shorter than the 6 MHz transducer

false

What is the wavelength of the 3 MHz transducer is shorter then the 6 MHz

false

What is the wavelength of 3MHz sound in soft tissue

0.51 mm

Image quality is affected by wavelength

true

If the frequency increases wavelength

decrease

The relationship between frequency and wave length is

inverse

Which pulse has a longer wavelength

from a 2 MHz

The number of wavelength passing a given point in a single second is called

frequency

Stiffness of a medium is the opposite of its

compressibility

When the elasticity of a medium is high the _____ is high

compressibility

The term bulk modulus is related to which quality

stiffness

The propagation speed used for soft tissue is

an average based on the usual percentages of each type of tissue