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amadaperedo
on FreezingBlue Flashcards.
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The term signal-to-noise ratio denotes:
The relative amplitude of the signal compared to the amplitude of the noise
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What receiver function converts the negative portion of the radiofrequency (RF) signal to positive?
Rectification
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Pre-processing functions may be defined as:
A function that is performed before the echo data are stored in memory
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Increasing the dynamic range setting affects the ultrasound image by:
Decreasing image contrast
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When you adjust the TGC, what components of the ultrasound system implements the changes?
Receiver
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A typical value for the duty factor in diagnostic sonographic image is:
0.1-1%
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Pulse repetition period is the inverse of:
Pulse repetition frequency
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What system component determines the pulse repetition frequency?
Pulser
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In ultrasound systems, the range equation is used to determine which of the following?
Reflection depth
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You have increased the output power by 10 dB. The signal intensity has:
Increased by a factor of 10
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What is the purpose of the preamplification of the incoming signal that occurs in the transducer assembly?
To increase echo voltages before noise is induced through the cable
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What function of the receiver converts electronic signal from radiofrequency to video form?
Demodulation
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What component of the ultrasound system converts the electric energy provided by the pulser into acoustic pulses transmitted into the patient?
Transducer
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The incoming raw echo signals must be compressed into a smaller dynamic range because:
The display cannot accommodate the wide dynamic range of the incoming signals
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Which of the following is NOT a function of the receiver?
Dynamic aperture
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What system function is limited by the speed of sound in tissue?
Pulse repetition frequency
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What control should you adjust to modify the image if the attenuation coefficient of the tissue is very high?
Compensation
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You made changes to the following controls during a sonogram. Which adjustment increased the duty factor?
Increasing pulse repetition frequency
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What is the advantage of using Write zoom instead of Read zoom magnification?
Write zoom provides better spatial resolution than Read zoom
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How is reflector depth determined with pulse-echo ultrasound?
Echo arrival time
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What effect will you detect in the image if you increase the threshold control?
Decreased appearance of weak echo signals
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What can you do to improve the temporal resolution while scanning?
Decrease the acoustic scan line density
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The number of images displayed per second in real-time imaging is termed the:
Frame rate
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Which scanning mode does NOT rely on the principle of echo ranging to determine interface location?
Transmission
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Which display mode may be used to calculate distance measurements?
A-mode, B-mode and M-mode
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Which of the following best describes M-mode?
Depth of reflectors along a single line of sight vs. time
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Which is an assumption of sonographic imaging that determines how detected echoes are mapped in the image?
Echoes originate from the most recently transmitted pulse
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What physical concept allows us to determine the location of an interface by measuring the elapsed time between the transmitted pulse ultrasound wave and the detected echo from that interface?
Echo ranging
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The elapsed time between the transmitted pulse and the detected echo is 26 microseconds. How far is the interface from the transducer?
2 cm
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During a sonographic exam, you adjusted the following controls. Which one was most likely to have affected the frame rate?
Scan depth
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