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Ultrasound Physics
Ch.4-5 pulsed sound and intensity
41
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Undergraduate 1
01/23/2021

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Term
If frequency increases, the spatial pulse length___
Definition
decreases
Term
Spatial pulse length is__
Definition
wavelength x number of cycles in pulse
Term
Spatial pulse length is the product of__
Definition
wavelength and cycles per pulse
Term
SPL is determined by__
Definition
both Source and Medium
Term
Pulse A is from a 5 MHz transducer and pulse B is from a 10 MHz transducer. Both pulses have 4 cycles per pulse.
Definition
pulse A will have a greater SPL
Term
PRP is defined as__
Definition
the pulse transmit or "on" time plus the pulse listening or "off" time.
Term
The number of pulses occurring in 1 sec is called the___
Definition
pulse repetition frequency
Term
If the PRF increases, the PRP__
Definition
decreases
Term
(True or False). Pulse repetition period is the reciprocal of pulse duration
Definition
false
Term
The range of PRF used in diagnostic ultrasound is__
Definition
1 to 10 kHz
Term
If the depth of view increases, the PRF___
Definition
decreases
Term
When you change the PRF you are changing__
Definition
the number of pulses per second
Term
Duty factor is determined by__
Definition
the depth of view
Term
What is the value of the duty cycle for continuous wave (CW)U/S?
Definition
100%
Term
PRF depends on__
Definition
source of the sound waves/transducer
Term
If the PRF decreases, the duty factor__
Definition
decreases
Term
Duty factor can be changed by the sonographer.
Definition
True
Term
In CW U/S, which of the following are the same?
Definition
SAPA
SATA
Term
The units for duty factor are__
Definition
a ratio without units
Term
Which is the highest intensity?
Definition
SPTP
Term
Spatial intensity is__
Definition
The beam intensity across the area being scanned
Term
The beam uniformity coefficient describes__
Definition
the spread of a beam in space (SP/SA factor)
Term
Pulse duration is equal to___
Definition
period x number of cycles in pulse
Term
If the depth of view increases, the pulse duration___
Definition
remains unchanged
Term
What happens to SPL if depth of view increases using the same transducer?
Definition
remains the same
Term
If you increase the depth of view from 2cm to 3cm, the SPL__
Definition
does not change
Term
PRP and PRF can be changed by___
Definition
altering depth of view
Term
Two waves can have identical pulse repetition frequencies, even if their frequencies are different.
Definition
True
Term
Duty factor depends on the frequency of the transducer.
Definition
False
Term
The PRF of a 5 MHz transducer is greater than the PRF of a 2.5 MHz transducer.
Definition
True
Term
In pulsed ultrasound, the maximum value of the duty factor is__
Definition
Less than 100%
Term
When the SPL increases, the duty factor__
Definition
Increases
Term
Two pulses are created by different transducers and both have the same frequency, the pulse containing more cycles has__
Definition
longer pulse duration
Term
What are the units of intensity?
Definition
watts/cm2
Term
Intensity is equal to___
Definition
power/area
Term
Temporal intensity is__
Definition
the beam intensity during the transmitting time
Term
The spatial intensity is usually highest at__
Definition
the center of the beam
Term
Intensities are important because___
Definition
Bioeffects on the tissue being scanned
Term
Pulse duration is determined by__
Definition
source
Term
Power divided by beam areas is equal to___
Definition
intensity
Term
The units of pulse duration are units of____
Definition
time
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