ch19-20

34問 • 1年前

問題一覧

Power Doppler is limited because

it does not show direction of flow

What method is used to steer the color box?

electronic time delays

If you increase the wall filter during Doppler sampling, it will a. increase spectral broadening b. reduce display of low-frequency shifts c. reduce aliasing d. increase visibility of low velocity flow

What technique is used to perform the spectral analysis? a. Fast Fourier Transform b. Autocorrelation c. Phase Quadrature d. Zero-crossing detection

If you increase the transmit frequency of the color Doppler, what will happen? a. reduced aliasing b. reduced flash artifact c. improved penetration for deep vessels d. improved sensitivity to slow flow

If you lower the color threshold, what will occur? a. decreased flash artifact b. increased color fill within the vessel c. increased frame rate d. improved color penetration

From the Doppler equation, which would NOT be true? a. increasing Doppler frequency will incase frequency shift b. increasing angle will increase frequency shift c. Decreasing reflector speed will decrease frequency shift d. no shift is detected with the beam is perpendicular to the reflector e. velocity information can be obtained from the frequency shift even if the angle is known

What does brightness of the Z axis on the Doppler spectrum refer to? a. amplitude b. velocity c. bandwidth d. frequency shift

What can you adjust to improve the frame rate? a. decrease PRF b. decrease size of color box c. decrease scan line density d. increase wall filter

b&c

With the following scan parameters, what is the frequency at which aliasing will occur? 5 MHz fundamental frequency, 3 kHz PRF, 4 cm depth, 1.5 mm sample volume width. a. 5 MHz b. 3 kHz c. 1.5 MHz d. 12 kHz

The faster technique used to obtain the MEAN Doppler frequency in color flow is a. Fast Fourier Transform b. Phase Quadrature c. Autocorrelation d. Frequency shift comparison

If you see spectral broadening in the spectral analysis display, it usually means a. flow velocity b. accelerated flow c. turbulent flow d. high resistance flow

Which of the following refer to the number of pulses used to measure the velocity along one scan line? a. packet size b. ensemble length c. PRF d. pulse duration e. Color gate

a&b

Which term refers to the axial length of the sample volume a. packet size b. color gate c. line density’

What adjustments can you make to eliminate color flash artifact? a. Decrease PRF b. increase wall filter c. increase Doppler frequency d. increase color gain

Which of the following is NOT true for turbulent flow? a. can be predicted with the Reynolds number b. causes increase in pressure downstream c. is affected by velocity d. occurs with abrupt changes in vessel diameter e. is responsible for murmurs, bruits, and thrills

Which of the following are true regarding color Doppler images? a. B mode image and color information are from the same set of pulses b. color image is superimposed over the B mode image c. Color and B mode are usually obtained from the same frequency sound beams d. B mode image is usually obtained at a lower frequency than color image

If you increase the packet size, what will result? a. decreased penetration for depth b. decreased sensitivity to flow c. decreased frame rate d. increased spectral broadening

Which control on the control panel adjusts Doppler PRF? a. packet size b. Gain c. Spectral velocity scale d. Dynamic range

When you increase the Doppler frequency, what occurs? a. increased velocity measurement b. Increased Doppler frequency shift c. Increased frame rate d. Increased Nyquist limit

If you lower the PRF, which of the follow occur? a. wall filter is increased b. frame rate is increased c. Line density is increased d. Nyquist limit is decreased e. Doppler frequency is decreased

What part of the Doppler spectrum in color-encoded with color Doppler a. the velocity b. the bandwidth c. the amplitude d. the frequency shift

Which control determines the gray-scale brightness at which color will display instead of gray-scale? a. line density b. persistence c. priority d. ensemble length

With reference to the Doppler equation, the frequency shift will increase by increasing the a. Doppler angle b. transmit frequency c. pulse length d. PRF

What affects the spatial resolution of the color image? a. line density and ensemble length b. ensemble length and priority c. frequency and line density d. priority and frequency e. frequency and ensemble length

The term variance refers to a. velocity threshold b. frequency threshold c. velocity range

Adjustments to overcome aliasing do NOT include a. using a higher fundamental frequency b. switching to CW Doppler c. increasing the velocity scale d. moving the spectral baseline

The frequency of the Doppler samples is determined by the a. frequency of echoes b. the fundamental transmitted frequency c. the Doppler shift d. The pulse repetition

In pulsed Doppler, which of the following do not affect the shape and size of the sample volume? a. transmitted pulse length b. slice thickness c. beam width d. gate size e. spectral scale range

Which of the following is/are true of pulsed Doppler? a. has a duty factor of 100% b. receives a signal that is not determined by sample size c. does not alias d. determines depth by echo arrival time

Although the signals from CW Doppler are not as complex, only pulsed Doppler can do a. depth location b. frequency shift c. determine the presence of flow d. determine direction of flow

Which control removes low frequencies and displays a clean zero baseline? a. high pass filter b. low pass filter c. dynamic range d. gain

Which of the following occur to Doppler frequency shift with high velocities in the vessels? a. increased amplitude b. decreased bandwidth c. increased frequency shift d. increased attenuation

What adjustments can you make to decrease aliasing? a. decrease angle of incidence b. change the wall filter c. increase PRF d. Increase Doppler frequency

ch 6 AP

ユーザ名非公開 · 20問 · 1年前

ch 6 AP