PollEV 19,20,21

A maximum Doppler shift is obtained when the angle between the direction of blood flow and the direction of the sound beam is ______ degrees

0

Two ultrasound transducers are used to perform doppler exams on the same patient. The exams are identical except that the transducer frequencies are 5MHz and 2.5 MHZ. Which transducer will measure the highest doppler shift?

5 MHz

What information does the doppler shift provide to us on our ultrasound system, concerning blood cells?

velocity

When blood cells are moving away from the transducer, the doppler shift will be

negative

The doppler shift is measured in _________ and has units of ________

frequency, Hz

When using a 4MHz transducer, a doppler shift of 3,000Hz is recorded. What will the doppler shift be when a 2Mhz transducer is used?

1500 Hz

All of the following are related to a dedicated CW doppler transducer except

wide bandwidth

Spectral analysis of color flow doppler is most commonly performed by which of the following techniques?

autocorrelation

Which of the following color maps differentiates between laminar and turbulent flow?

variance

The "2" in the doppler equation represents

two doppler shift

A duplex ultrasound system displays ______ and ________ information

2D and doppler

When the angle of the sound beam to blood flow is 90 degrees, the cosine or doppler shift is

0

What type of signal processing technique is used for bidirectional doppler?

phase quadrature

The largest disadvantage to CW doppler is

range ambiguity

With PW doppler, the greatest advantage is

freedom from range ambiguity artifact

What occurs when the Nyquist limit is exceeded in spectral doppler

aliasing

Which of the following is a way to reverse or fix aliasing

raise Nyquist limit and use CW doppler

A system has three transducers with frequencies of 7.5Mhz, 5Mhz, and 3.5Mhz. Aliasing appears using the 5Mhz transducer during a pulsed doppler exam. What is a sonographer to do?

use the 3.5 MHz transducer

lowering the frequency ________ aliasing

reduces

Lobe artifacts degrade____________ resolution

lateral

Which artifact produces an image with an incorrect number of reflectors

side lobes

this card is for assumptions

6

Spectral broadening occurs with

turbulent flow

What type of artifact appears as multiple, equally spaced echoes positioned parallel to the sound beam?

reverberation