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Ultrasound Physics: SPI Review, ALL Chapters, Formulas & Relationships
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Ultrasound Physics: SPI Review, ALL Chapters,Formulas & Relationships
The fundamental or operating frequency Correct Answer: is affected by the thickness of the PZT
element (thickness = ½ wavelength)
Which of the following could not be used as the coupling medium (gel)? Correct Answer: barium sulfate
The piezo electric effect is best described as Correct Answer: deformation from voltage sent to the
crystals
How thick is the element if the frequency is 3MHz? Correct Answer: half the wavelength of the wave in
the PZT
The gel has greater impedance that the matching layer but less than the impedance of the PZT elements'
T/F Correct Answer: False
The impedance of the PZT crystals is higher than the impedance of skin tissue. T/F Correct Answer: True
Place the following in order of highest to lowest impedance. Correct Answer: PZT > matching layer > gel
> skin
The damping layer decreases the PRP at a specific imaging depth. T/F Correct Answer: False
The backing material decreases the duty cycle at a particular PRF. T/F Correct Answer: True
The pulse duration increases because of the backing material. T/F Correct Answer: False
The backing material decreases the Q factor. T/F Correct Answer: True
The backing material decreases the SPL. T/F Correct Answer: True
If the transmitted pulse has frequencies from 3.5 MHz to 6.5 MHz, what is the bandwidth? Correct
Answer: 3.0 MHz
Which of the following is not a result of the damping layer? Correct Answer: sensitivity increases
Which of the following would cause the PZT properties to be eliminated? Correct Answer: high
temperatures
Which of the following affect the frequency of the transmitted beam from CW ultrasound? Correct
Answer: ultrasound system electronics (CW is determined by the electrical signal from the pulser)
Which of the following are most important in producing the frequency of the beam in soft tissue Correct
Answer: propagation speed of the PZT elements
,In PW ultrasound, the Q factor should be made as large as possible. T/F Correct Answer: False
The measurement that relates bandwidth to the operating frequency is Correct Answer: Q factor
The _____ of the transducer is the ratio of the operating frequency to the bandwidth Correct Answer: Q
factor
When a transducer is covered with a sterile cover with gel on the inside, what can the transducer not
come into contact with in order to create an image? Correct Answer: talcum powder
If the frequency of the electrical excitation voltage of a pulsed wave transducer is 6MHz, the main or
center frequency of the transducer is 6MHz. T/F Correct Answer: False
If the pulse repetition frequency of a transducer is increased, the frequency of US produced by the
transducer remains the same. T/F Correct Answer: False
The diameter of the active element of a transducer helps to determine the frequency of the US
produced by the transducer. T/F Correct Answer: False
If the frequency of the electrical excitation voltage of a continuous wave transducer is 6MHz, the main
or center frequency of the transducer is 6MHz. T/F Correct Answer: True
Two piezoelectric crystals are made from the same material. The thicker crystal will make a pulsed
transducer with a higher frequency. T/F Correct Answer: False
For a pulsed wave transducer, if the PZT crystal thickness is doubled, then the frequency of sound is
halved. T/F Correct Answer: True
The normal propagation speed for piezoelectric material is approximately three to five times greater
than soft tissue. T/F Correct Answer: True
The acoustic impedance of the matching layer equals the acoustic impedance of skin. Correct Answer:
False
A broadband transducer is more characteristic than a narrow bandwidth for imaging transducers. T/F
Correct Answer: True
A very high "Q" factor transducer is more common than low "Q" factor for diagnostic imaging. Correct
Answer: False
The impedance of a transducer active element is 1,900,000 rayls and for the skin is 1,400,000 rayls.
What is an acceptable impedance for the matching layer? Correct Answer: 1,726,000 rayls
With a pulsed wave transducer, which of the following occurs if the PZT thickness is halved? Correct
Answer: frequency is doubled
,With a pulsed wave transducer, which of the following occurs if the PZT thickness is doubled? Correct
Answer: frequency is halved
Which of the following does not fit with the others?
Broadband, backing material, short pulse, good lateral resolution, low Q Correct Answer: good lateral
resolution
Which of the following are not a natural element?
Quartz, Rochelle salts, tourmaline, lead titanate zirconate Correct Answer: lead titanate zirconate
Mechanical energy into electrical energy and vice versa is: Correct Answer: Piezoelectric property
Transducers are cleaned with a high temperature germicide. T/F Correct Answer: False
Using a transducer with a cracked plastic covering may shock patient. T/F Correct Answer: True
Damping or backing material reduces the # of cycles per pulse and cuts down the ringing. T/F Correct
Answer: True
Damping layer creates longer pulses with good quality factor. T/F Correct Answer: False
Damping material reduces sensitivity and efficiency of transducer. T/F Correct Answer: True
Dampening material in a transducer acts to:
Increase the sensitivity Correct Answer: False
Dampening material in a transducer acts to:
Increase the pulse length Correct Answer: False
Dampening material in a transducer acts to:
Decrease the pulse duration Correct Answer: True
Dampening material in a transducer acts to:
Improve the system's lateral resolution Correct Answer: False
Dampening material in a transducer acts to:
Improve the system's longitudinal resolution Correct Answer: True
Dampening material in a transducer acts to:
Narrows the bandwidth Correct Answer: False
Dampening material in a transducer acts to:
Decrease the quality factor Correct Answer: True
SPI ultrasound physics review
, What is frequency determined by? Correct Answer: The source, thickness of piezoelectric element and
propagation speed to a lesser degree
Thicker element is equal to ________ frequencies Correct Answer: Lower
What is the reciprocal of frequency and what is the symbol Correct Answer: Period, T
The time it takes for 1 cycle to occur Correct Answer: Period
What is propagation speed determined by Correct Answer: Stiffness and density of the medium
Propagation speed of sound through soft tissue Correct Answer: 1,540 m/s
Increasing the stiffness of a tissue does what to the propagation speed? Correct Answer: Increases
Increasing the density of a tissue does what to the propagation speed? Correct Answer: Decreases
Propagation speed of tissues from slowest to fastest Correct Answer: Air, fat, water, liver, blood,
muscle, bone
What is the distance over which one cycle occurs? Correct Answer: Wavelength
What happens to frequency when you increase the wavelength? Correct Answer: Decreases
What is the wavelength symbol Correct Answer: Lambda
What is the wavelength equation? Correct Answer: Propagation speed divided by the frequency
Units of wavelength Correct Answer: Mm, m, km
What is wavelength determined by? Correct Answer: Source and medium
What describes the strength of the sound wave? Correct Answer: Amplitude
What happens to a beam as it travels? Correct Answer: Decreases in amplitude and intensity due to
attenuation
What does amplitude represent on the chart of a wave? Correct Answer: The height of a vibration
What does pascals measure? Correct Answer: Pressure amplitude
What happens to amplitude when you increase depth? Correct Answer: Decreases due to attenuation
What is amplitude determined by? Correct Answer: The source
Related to strength of the beam Correct Answer: Power
What is the unit for power? Correct Answer: Watts
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