Principles & Instrumentation Pt 1 Flashcards
Which of the following would lead to misregistration of data and incorrectly placed pixels in a deeper than normal location on the image
A. when less than 75% beam transmission occurs
B. the ultrasound system is calibrated to 1600m/s as the speed of sound in soft tissue
C. the ultrasound system is calibrated to 1450 m/s as the speed of sound in soft tissue
D. a highly reflective media boundary
C
Activation of B-color is used to improve
A. elevational resolution
B. contrast resolution
C. temporal resolution
D. spatial resolution
B, colorized functions are used to improve contrast resolution
When evaluating heavily calcified arteries, what system settings should be increased to improve the demonstration of flow in the vessels
A. frequency and output power
B. persistence and sensitivity
C. color gain and angle of insonation
D. velocity scale and persistence
B
In order to improve spatial resolution and signal-to-noise ratio, _______ uses frequency modulation to manipulate the transmitted beam
A. tissue doppler
B. harmonic imaging
C. spatial compounding
D. coded excitation
D
What system setting should be adjusted to better visualize the possible stone in the ureter posterior to the bladder
A. reduce the rejection settings
B. increase the dynamic range
C. Turn off spatial compounding
D. turn up the overall gain
C, spatial compounding reduces appearance of enhancement and shadowing, turning this off will show the shadowing of the stone
Which of the following is a primary factor in determining the frame rate of an ultrasound system
A. transducer frequency
B. output power
C. axial resolution
D. propagation speed in tissue
D
What is the contrast resolution for a system with a 4 bit memory and 32 dB dynamic range
A. 0.8dB/shade
B. 2dB/shade
C. 8dB/shade
D. 20dB/shade
B, contrast resolution=dynamic range/shades, 4 bit memory will use 16 shades of gray, 32dB/16 shades =2dB/shade
Which of the following imaging techniques would be used to best evaluate the volume of an irregular mass
A. harmonic 2D imaging in at least three imaging planes
B. elastography
C. harmonic 2D imaging in at least two imaging planes
D. 3D rendering
D
If the sonographer decreases the image depth, how will this affect the pulse repetition frequency
A. increase
B. non predictable without information on the pulse duration
C. decrease
D. no effect
A, a decrease in image depth will increase PRF, which increases frame rate
If the reflector is 5cm from the transducer, how long will it take a pulse to reach it
A. 0.3msec
B. 0.03msec
C. 0.6msec
D. 0.06msec
B, Range equation: distance to reflector- velocity x 1/2(time of flight), 5cm=0.5 m, 0.05 m=1540m/s x 1/2, 0.00003s= 1/2, 0.00006s or 0.06ms. The question asks for the time TO the reflector which is half of the round trip time=0.03 ms
What portion of the TGC curve is the deepest region attenuation compensation can occur
A. delay
B. toe
C. heel
D. knee
D
What effect does frequency compounding have on the image
A. reduce speckle artifact
B. increase the transmitted frequency
C. eliminate grating lobe artifact
D. improve temporal resolution
A
Which of the following is least likely to occur with low frequency, high amplitude waves
A. transient cavitation
B. low mechanical index
C. stable cavitation
D. high mechanical index
B
Pulse-echo systems use strength and _____ of the received signal to create the gray scale image. Magnitude and _____ of the signal are used to create the doppler display
A. time of flight, direction
B. intensity, luminance
C. amplitude, location
D. Magnitude, strength
A
Which of the following system functions converts the received signal from radiofrequency form to amplitude form
A. compression
B. demodulation/detection
C. coded excitation
D. bandpass filtering
B
Demodulation is only necessary when
A. high frequency transducers are used
B. the image is displayed in an LCD monitor
C. low frequency transducers are used
D. a television monitor is used to display the image
D
What is the period for a 5MHz transducer
A. 0.2 microseconds
B. 2 microseconds
C. 2 milliseconds
D. 0.02 microseconds
A, 5MHZ=5,000,000Hz, period= 1/frequency
period = 1/5,000,000=0.0000002s or 0.2 microseconds
Which system component converts the scan line data into image format for display
A. image processor
B. beam former
C. signal processor
D. scan converter
A
Frame rates can be improved by the use of what signal processing technique
A. demodulation
B. parallel processing
C. autocorrelation
D. fast fourier transformation
B
Which of the following parameters is NOT operator adjustable
A. mechanical index
B. frequency
C. intensity
D. PRF
B
While scanning, you decide to increase the image contrast. What console control will be adjusted
A. increase overall gain
B. increase compression
C. reduce demodulation
D. increase rejection
D
During an ultrasound exam of the liver, you change from a 5MHz transducer to a 3MHz transducer. How does the propagation speed through the liver change
A. increases
B. decreases
C. remains constant
D. unable to determine
C
What beam formation technique is used to produce the sector field of view in a phased array transducer
A. mechanical focusing
B. mechanical steering
C. electronic focusing
D. electronic steering
D
which of the following will not affect the signal to noise ratio on a 2D image
A. frequency compounding
B. temporal compounding
C. harmonic imaging
D. spatial compounding
B
When you change the PRF, this adjusts
A. # cycles per pulse
B. # pulses emitted per second
C. # cycles emitted per second
D. none of the above
B
Which of the following console controls will adjust the pulse duration
A. output power
B. imaging depth
C. adding a focal zone
D. none of the above
D, the pulse duration cannot be changed unless a new transducer is selected
If the amplitude of the ultrasound wave decreases by 1/2 with a constant beam area, what happens to the intensity of the beam
A. decreases to 25% of original value
B. increases by a factor of 4
C. doubles
D. decreases to 50% of original value
A (decreases by factor of 4)
The range equation is used to determine the
A. sensitivity of the US system
B. distance to a reflector
C. dynamic range of the US system
D. focal depth
B
Which of the following correctly lists how to estimate the volume of a structure on 2D imaging
A. length x width x height
B. length x width x 0.523
C. length x width x height x 0.523
D. length x width x height x 100%
C
Vessel wall thickness and plaque morphology are best evaluated in 2D when the beam is at what incident angle to the vessel
A. 0 degrees
B. 45 degrees
C. 60 degres
D. 90 degrees
D
Which of the following would brighten the image without affecting beam intensity
A. decrease monitor brightness
B. decrease rejection
C. increase the amplitude of transmitted sound
D. increase the amplitude of reflected sound
D
Which of the following correctly describes apodization
A. it is performed by maximizing the voltage of the central elements and reducing the voltage to the outer elements
B. It is a post processing function that adjusts contrast resolution
C. it is a post processing function that adjusts temporal resolution
D. it is used to remove the high frequency reflections outside the bandwidth
A
If the power of the beam is 24mW and the FOV is 2cm x 3cm, what is the average beam intensity
A. 0.4mW/cm^2
B. 4mW/cm^2
C. 7mW/cm^2
D. 0.7mW/cm^2
B, intensity= power/area, intensity= 24mW/6cm^2= 4mW/cm^2
The peak amplitude of the vertical spike on the A mode display corresponds to
A. the time to the reflector
B. the distance to the reflector
C. the strength of the reflection
D. the time to and from the reflector
C
Which of the following will improve lateral resolution at all depths on the image
A. decrease probe frequency
B. dynamic receive focusing
C. use >3 focal zones
D. dynamic transmit focusing
B
You are performing a liver ultrasound using the intercostal window and the entire image is very bright. What is the best way to adjust the image to the appropriate brightness level
A. adjust the far field TGCs
B. adjust the near field TGCs
C. adjust the power output
D. adjust the overall gain
C
Amplification of the received signal occurs in the
A. beam former
B. signal processor
C. image processor
D. image former
A
When harmonic imaging is turned on, it primarily improves _______ resolution
A. axial
B. temporal
C. lateral
D. contrast
C
The horizontal axis on the M mode represents the _____
A. motion
B. time
C. depth
D. frequency shift
B