US Physics 7-10

A received frequency that is less than the transmitted frequency is which of the following. (multiple answers)

Negative Doppler Shift, Flow Away from the Transducer, Retrograde Flow

The major reflector for Doppler ultrasound is which of the following?

Red Blood Cells

The Doppler shift is dependent on all of the following EXCEPT?

thickness of the vessel wall

The cosine of 180 is which of the following?

-1

In regard to Doppler ultrasound, the extracting of lower Doppler frequencies from higher transducer frequencies is called?

demodulation

Which of the following information is recorded by spectral Doppler?

velocity of the reflector

Inaccurate angle correction may result in spurious velocity determinations which may lead to a misdiagnosis.

true

Velocity refers to:

both speed and direction of red blood cells

This form of Doppler is used in a clinical setting simply to identify the presence of flow when direction of flow is of no consequence.

nondirectional Doppler

Simultaneous imaging and Doppler is termed?

Duplex imaging

When discussing "laminar flow" within a vessel, blood velocities are:

highest in the center and decrease to zero at the walls

Which of the following may be present in pulsed Doppler but NOT in continuous wave Doppler?

aliasing

The purpose of the FFT, fast Fourier transform program is to?

display the Doppler frequency spectrum

Aliasing in pulsed doppler occurs when:(May be more than one answer)

the Doppler frequency shift exceeds 1/2 the PRF, the sampling rate is less than 2 times the frequency of the signal.

A patient who has anemia should not have a Doppler exam performed because of the low concentration of red blood cells.

False

The strength of the Doppler signal from flowing blood is most closely related to:

the number of red blood cells in the beam

Absence of color on a color Doppler image always indicates no flow is present.

False

On color Doppler image, red always indicates flow toward the transducer and blue always indicates flow away from the transducer.

False

Color Doppler reports peak velocities.

False

Power Doppler can identify direction of flow but not velocities of flow.

False

The Doppler shift produces information about which of the following?

velocity

What is the current method of processing spectral Doppler signals?

fast Fourier transform

What is the current method for analyzing color Doppler information?

autocorrelation

When high velocities appear negative on the spectral tracing it is termed?

aliasing

All of the following are goals of quality assurance EXCEPT:

increase repeat scans

The AIUM 100 mm test object can evaluate grayscale.

False

Which of the following evaluates mock cysts and solid masses?

tissue equivalent phantom

Which of the following describes the system's ability to display similar reflectors in the phantom with echoes of equal brightness.

uniformity

Which of the following types of resolution displays the smallest distance at which two pins parallel to the sound beam and are displayed as two distinct echoes?

Axial

A region between the transducer to a depth of meaningful reflections is called which of the following

dead zone

Which one of the following is a requirement for any lab?

record keeping

All of the following can be used to evaluate Doppler systems EXCEPT:

tissue equivalent phantom

Which of the following might a Doppler phantom may assess?

All the above

Quality assurance can only be performed by engineers or physical scientists.

False

Quality assurance should be performed:

routinely and periodically

The science of identifying and measuring the characteristics of an ultrasound beam that are relevant to its potential for producing bioeffects is which of the following?

dosimetry

Which of the following is related to the likelihood of harmful bioeffects from cavitation?

mechanical index

Research performed within the living body is known as:

in Vivo

Which of the following is the thermal index of soft tissue?

TIS

A high mechanical index will cause:

more cavitation

It is appropriate to use diagnostic ultrasound in a non medical setting for entertainment.

False

Which of the following is generally true of diagnostic ultrasound?

harmful bioeffects do not occur but it would be irresponsible to ignore the possibility they may in the future

Which of the following is correct for an unfocused beam?

100 mW/cm sq

Which of the following is the correct intensity for a focused beam?

1 W/cm sq

No confirmed bioeffects on patients or sonographers have been found with the use of diagnostic ultrasound.

True

Which of the following is the unit for impedance?

rayls

Which of the following is the unit for pressure?

Pa

Which of the following is the processor used to analyze spectral Doppler?

fast Fourier transform

Which one of the following will give the most accurate spectral Doppler information?

180 degrees

Adding more focal zones will do which of the following?

decrease temporal resolution

You are using spectral Doppler to evaluate the heart pressure and need to know exactly where the velocities are coming from. In this case you would use which of the following?

PW Doppler

Adding too much filter or decreasing the filter too much will lead to a loss of information on the spectral Doppler waveform.

True

Power Doppler can determine the direction of flow but not the speed of blood flow.

False

Which of the following is the half value layer thickness of a 7 MHz transducer?

0.85 cm

What is the attenuation in dB using a 2.5 MHz transducer and imageing to a depth of 16 cm?

20 dB

What is the period of a 10MHz transducer?

0.1 microseconds