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Question | Answer |
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According to ALARA which parameter should be minimized? | |
What is the result of an increase in the peak rarefactional pressure? | |
What does a hydrophone measrure? | acoustic output of an ultrasound image system |
To what is penetration depth inversely related? | |
If an echo is recieved 25 microseconds after transmission, wha is the depth of the structure? | |
Besides a sound wave striking a boundary between two tissue interfaces at oblique incidence, which other condition must be present for refraction to occur? | |
Which artifact is produced by the reduction in echo signal amplitude deep to a strongly reflecting or attenuating structure? | refraction, enhancement, shadowing, reverberation |
Which factor is most important when choosing the ultrasound exam? | cell size, impedance, depth, velocity |
Which transducer array configuration results in a small footprint that is electronically steered and focused? | linear phased, linear sequential, annular, curved linear |
What is increased if pulse duration is decreased? | bandwidth, line density, frame rate, duty factor |
In an unfocused transucer, what is the region between the transducer face and the point where the beam diverges? | side lobe, focal zone, near zone, far field |
Which factor causes lateral resolution to vary with depth? | beam width, pulse length, propagation speed, acoustic impedance |
What is decreased with the nuber of acoustic lines per frame is increased without changing the max depth? | SPL, frame rate, PRF, receiver dynamic range |
Which artifact is indicated by the arrows? pic | comet tail, shadow produced by diaphragm, mirror image, acoustic enhancement |
What does read zoom do? | rescan region of interest, discard initial data obtained during scanning, increase number of scan line in ROI |
What does frequency compounding improve? | temporal resolution, contrast resolution, elevational resolution, lateral resolution |
What may cause point reflections to appear as horizontal lines rather than dots on the B-mode image? | propagation velocity, beam widthm transducer bandwidthm attenuation |
How does adjusting the overall gain change the brightness of image? | adjust strength of transmitted soundpulse, adjust amplification of receive voltage, changes dynamic range, adjust ampliturde with depth |
What is round trip time in soft tissue for an echo from a reflection depth of 1 cm? | 1.54 m us, 6.5 m/s, 13 m/s, 26 m/s |
What is the effect on PRP if PRF is doubled? | quartered, halfed, doubled, unchaged |
What does coded excitation improve in addition to penetration? | lateral resolution, signal-to-noise ratio, frame rate, dynamic range |
An increased in which parameter will improve accuracy of velocity measurement with autocorrelation? | color field of view, packet size, wall filter setting, transmitted frequency |
Assuming PRF cannot be futher increased, what would mimimizee the observed artifact? | adjust sweep speed, adjust baseline, increase dynamic range, increased transmitted frequency |
The reflections are moving at the same speed in the direction shown. For which reflection will the frequency of the received echo be the highest? | a,b,c,d |
If the Doppler shift frequency is 1KHz when a vessel is 2 cm depth, what is the frequency shift at 4cm? | 0.5KHz, 1 KHz, 1.5KHz, 2 KHz |
What does the color image flow demonstrate? pic | gain set too high, velocity scale too low, packet size too large, transmitt frequency too high |
Which signals are eleminated by wall filter in spectral Doppler display? | low frequency, low intensity, high frequency, high intensity |
Which parameter would change on the phantom test if the SPL were made longer? | axial resolution, lateral resolution, horizontal distance registration, sensitivity |
Which group is used to evaluate dead zone? pic | a,b,c,d |
What is demonstrated in the is image from a linear array scanhead being placed on a uniform mimicking phantom? pic | TGC not set properly, system ??, focus control malformation, transducer damged |