Q: The best way to increase the near field length of an ultrasound beam is to:
Answer:
increase transducer diameter
Q: The range of frequencies produced by a damped PZT element is called:
a. fundamental frequencies
b. Q Factor
c. near field
d. bandwith
Answer:
d. bandwidth
Q: The percentage of time that the ultrasound instrument is emitting ultrasound is called:
a. PRF
b. pulse duration
c. pulse repetition period
d. duty factor
Answer:
d. duty factor; the maximum value is 1, the minimum is 0
Q: The unit of duty factor is:
a. Hz
b. mm
c. ms
d. unitless
Answer:
d. unitless
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<\/a><\/figure>\n\n\n\nWhich gain will increase the risk of bioeffects?
a. transmit
b. receive
c. gain
d. overall gain
a. transmit<\/p>\n\n\n\n
Which of the following is considered the memory of an ultrasound instrument?
a. pulser
b. transducer
c. receiver
d. beam former
e. digital scan converter
f. display monitor
e. digital scan converter<\/p>\n\n\n\n
Spectral broadening suggest:
a. laminar flow
b. turbulent flow
c. flow away from the transducer
d. flow towards the transducer
b. turbulent flow<\/p>\n\n\n\n
With pulse wave Doppler axial resolution:
degrades<\/p>\n\n\n\n
What color is usually use in color flow Doppler variance map to indicate turbulent flow?
green<\/p>\n\n\n\n
Doppler high pass filter eliminates:
high amplitude signals; low velocity flow<\/p>\n\n\n\n
The Doppler wall filter is considered a:
high pass filter<\/p>\n\n\n\n
The Nyquist Limit is equal to:
a. propagation speed x frequency
b. propagation speed\/ wavelength
c. PRF\/2
d. 4xV^2
c. PRF\/2<\/p>\n\n\n\n
Multiple echoes, equally spaced originating from a gas bubble is called:
a. comet tail
b. ring down
c. slice thickness artifact
d. multipath
b. ring down<\/p>\n\n\n\n
An increase in red blood cell velocity will_____ the Doppler Shift:
a. increase
b. decrease
c. not change
d. cannot be predicted
a. increase<\/p>\n\n\n\n
The primary advantage of CW Doppler is:
a. range resolution
b. range discrimination
c. range ambiguity
d. range gating
e. absence of sampling rate
e. absence of sampling rate<\/p>\n\n\n\n
The range for ultrasound begins:
a. 20 Hz
b. 20,000 Hz
c. 2 MHz
d. 15 MHz
b. 20,000 Hz (useful frequency range for clinical imaging is 2MHz-10MHz)<\/p>\n\n\n\n
Which instrument control affects the amplitude (dB) of the outgoing signal:
a. gain
b. receiver gain
c. TGC
d. transmit gain
e. overall gain
d. transmit gain; amplitude can be affected by the sonographer<\/p>\n\n\n\n
Which of the following is used to convert Doppler shift information into color:
a. high PRF
b. fast Fourier transform
c. autocorrelation
d. time interval histogram
c. autocorrelation
b is incorrect because fast Fourier transform is the method used to process conventional Doppler shift information but is too slow a method for color Doppler<\/p>\n\n\n\n
Pulse repetition frequency
Number of pulses that an ultrasound system transmits into the body each second. Hz. Typically 4-15 KHz. PRF and depth of a view are inversely related: When system is imaging deeper, the pulse repetition frequency is lower.
Also the number of pulses created each second<\/p>\n\n\n\n
The best way to increase the near field length of an ultrasound beam is to:
increase transducer diameter<\/p>\n\n\n\n
The range of frequencies produced by a damped PZT element is called:
a. fundamental frequencies
b. Q Factor
c. near field
d. bandwith
d. bandwidth<\/p>\n\n\n\n
The percentage of time that the ultrasound instrument is emitting ultrasound is called:
a. PRF
b. pulse duration
c. pulse repetition period
d. duty factor
d. duty factor; the maximum value is 1, the minimum is 0<\/p>\n\n\n\n
The unit of duty factor is:
a. Hz
b. mm
c. ms
d. unitless
d. unitless<\/p>\n\n\n\n
Quality Factor= Fundamental frequency\/ bandwidth
This allows doses of different types of radiation to be compared for their biological effects.<\/p>\n\n\n\n
Clinical imaging transducers are:
wide bandwidth; low q factor<\/p>\n\n\n\n
Power\/area=
Intensity<\/p>\n\n\n\n
Increasing wavelength will _<\/strong><\/em><\/strong> frequency. All of the following directly affect frame rate except: A reflection will occur at the boundary of two media if the acoustic impedences of the two media are: A mechanical transducer utilizes: The transducer frequency is primarily determined by the transducer element: A strongly focused transducer implies a: B-mode displays reflector: An increase in the number of pixels on the display will improve: Propagation speed is determined by: Increasing transmit gain increases everything except: The correct depth placement of reflectors depends primarily upon: Which of the following will increase the color flow jet area displayed? Increasing propagation speed: The most common type of transducer used in echo is: Decibels are the units for all of the following except: What are the four acoustic variables:<\/p>\n\n\n\n Frequency is Pulse duration Wavelength An increase in packet size will _<\/em><\/strong> the frame rate The range for audible sound is: The wavelength of a 1MHz transducer is: The average speed of sound in soft tissue is: An increase in overall gain will result in all of the following except: Reject eliminates: There have been no proven biological effects for unfocused transducers for intensities below: The primary cause of attenuation of ultrasound in soft tissue is caused by: Resolution artifact Damping does not decrease: Spectral Broadening Refraction autocorrelation PRF Period Period Calculation How do you decrease period? Impedance The unit for impedance?
a. increase
b. decrease
c. not change
d. cannot be predicted.
b. decrease<\/p>\n\n\n\n
a. depth of penetration
b. field of view
c. number of focuses
d. line density
e. beam width
e. beam width<\/p>\n\n\n\n
a. equal
b. different
c. unchanged
d. cannot be predicted
b. different<\/p>\n\n\n\n
a. transmit focus
b. receive focus
c. fixed focus
d. dynamic aperture focusing
c. fixed focus; sonographer cannot determine the location of # of foci. mechanical transducer uses cross sectional imaging, rotating wheel, wobbler, oscillating mirror<\/p>\n\n\n\n
a. diameter
b. thickness
c. propagation speed
d. type
b. thickness<\/p>\n\n\n\n
a. short focal length; decreased beam divergence
b. medium focal length; increased beam divergence
c. long focal length; no beam divergenc
d. short focal length; increased beam divergence
d. short focal length; increased beam divergence<\/p>\n\n\n\n
a. amplitude and distance
b. amplitude and velocity
c. power and direction
d. depth and speed
a. amplitude and distance<\/p>\n\n\n\n
detail resolution<\/p>\n\n\n\n
a. frequency
b. harmonics
c. bandwidth
d. bulk modulus
d. bulk modulus<\/p>\n\n\n\n
frequency<\/p>\n\n\n\n
a. frequency
b. period
c. power
d. propagation speed
d. propagation speed<\/p>\n\n\n\n
a. increase color gain
b. increase velocity scale
c. increase frequency
a. increase color gain<\/p>\n\n\n\n
air, soft tissue, bone<\/p>\n\n\n\n
sector phased array<\/p>\n\n\n\n
a. amplitude
b. transmit gain
c. gain
d. attenuation
e. TGC
f. dynamic range
e. intensity
e. intensity= mW\/cm2<\/p>\n\n\n\n\n
Cycles per second (Hz)
not affected by sonographer
increase frequency; decrease depth<\/p>\n\n\n\n
period (ms) x # of cycles in a pulse<\/p>\n\n\n\n
the length of one cycle
wavelength= propagation speed\/ frequency
1.54\/3MHz= .5mm<\/p>\n\n\n\n
Decrease<\/p>\n\n\n\n
20 Hz- 20kHz<\/p>\n\n\n\n
1.54\/1= 1.54mm<\/p>\n\n\n\n
1540m\/s; 1.54km\/s; 1.54mm\/us<\/p>\n\n\n\n
a. increase in image brightness
b. increase in output power
c. increase in amplification of the returning signal
d. decrease risk in bioeffects
b. increase in power<\/p>\n\n\n\n
low amplitude signals<\/p>\n\n\n\n
100mW\/cm2 SPTA<\/p>\n\n\n\n
absorption<\/p>\n\n\n\n
When two structures parallel to the ultrasound beam are displayed as one reflector.<\/p>\n\n\n\n
bandwidth<\/p>\n\n\n\n
The widening of the doppler shift spectrum. Meaning the increase of the range of doppler shift frequencies present, owing to a broader range of flow speeds encountered by the sound beam.<\/p>\n\n\n\n
Change in direction of a wave when it changs speed as in travels from one material to another. The change in the direction of sound as it crosses a boundary.<\/p>\n\n\n\n
used to convert Doppler shift information into color.<\/p>\n\n\n\n
Pulse Repetition Frequency. The rate at which pulses are transmitted, given in hertz or pulses per second; reciprocal of pulse-repetition time.<\/p>\n\n\n\n
the time per cycle
1-10usec<\/p>\n\n\n\n
1\/frequency
1\/5MHz= .2<\/p>\n\n\n\n
Increase frequency<\/p>\n\n\n\n
the opposition of sound propagation<\/p>\n\n\n\n
Rayls<\/p>\n\n\n\n