Chapter 6 Kremkau Flashcards by Billie Harney

the part of the instrument that accomplishes electronic beam scanning, apodization, steering, focusing, and aperture with arrays

beam former

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the portion of a system operating on Principle 2 that acquires the echo information from the signal processor, performs the retrospective, virtual-beam computations and sends the results to the display

image former

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an electronic device that rapidly performs calculations to accelerate the creation of images

Graphics processing unit (GPU)

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the beam

physical beam

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ultrasound waves are produced in pulses, not continuously, because the same crystals are used to generate and receive sound waves, and they cannot do both at the same time

pulse-echo principle

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a line produced on a display that represents ultrasonic echoes returning from the body

scan line

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an imaginary reception beam that can be thought of as determining the echo produced at each pixel location in the image

virtual reception beam

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an imaginary laser-thin transmitted ultrasound beam that can be thought of as producing the excellent detail resolution throughout the image that is accomplished with retrospective, computed beam forming

virtual transmission beam

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The underlying principle upon which conventional (Principle 1) sonography operates is:

the pulse-echo principle

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The underlying principle upon which more recent, sophisticated (Principle 2) sonography operates is:

the virtual beam principle

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Which is not needed with Principle 2 sonography?
a. transmitted beam
b. multiple-transmit focus
c. reception focus
d. TGC

multiple-transmit focus

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Which is not a reason for improvement of detail resolution with Principle 2 sonography?
a. shorter transmit pulses
b. reception focus at each pixel location
c. massive postprocessing with GPUs
d. retrospective beam forming

shorter transmit pulses

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Which is not a reason for improvement of temporal resolution with Principle 2 sonography?
a. shorter transmit pulses
b. fewer transmit pulses
c. no multiple focusing
d. speed of GPUs

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Which is not significantly improved with Principle 2 sonography?
a. axial resolution
b. lateral resolution
c. temporal resolution
d. contrast resolution

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Physical beam forming applies to ____ sonography

both principle 1 and principle 2

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Virtual beam forming applies to:

principle 2

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Multiple transmission focus control applies to:

principle 1

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Retrospective beam forming applies to:

principle 2

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Improving detail resolution sacrifices temporal resolution is true for:

principle 1

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Simultaneous gray-scale, Color-doppler, and spectral-Doppler applies to:

principle 2

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Principle 1 employs mostly:

focused ultrasound beams

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Principle 1 yields higher frame rates than Principle 2.

false

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Shear wave elastography operates on Principle 1

false

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Principle 2 enables the entire image to be in focus

true

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Principle 2 yields improved penetration

true

Principle 2 does not impact Doppler operations

false

Principle 2 produces laser-thin ultrasound beams

false

Multiple transmit focuses degrade temporal resolution with _____.

principle 1

Reception focus principle applies to:

both principle 1 nor principle 2

A doppler shift at 60 degrees is ____ what it would be at 0 degrees

one half

A change in doppler frequency caused by motion of a source or a reflector defines

Doppler effect

A nonsteady flow with acceleration and deceleration over the cardiac cycle is called _____

pulsatile flow

Continuous wave doppler shifts are detected within the _______

Overlapped region of the transmitting and receiving beams

Determining the direction of the doppler shift voltages is accomplished by the _______

Phase quadrature detector

Doppler measurements are not reliable at doppler angles greater than

Doppler shift does not depend on the

flow direction

Echoes arrive from the sample volume depth at a rate equal to

the pulse repetition frequency

for a given flow, the greater the doppler angle, the _____ the doppler shift

less

Gases, nutrients, and waste products are exchanged through the walls of

capillaries

if pressure differences in a straight vessel increase, the flow rate

increases

Motion toward the transducer demonstates

a positive Doppler shift

Poise is a unit given for ____

viscosity

Poiseuille's equation states that, if the flow rate increases the

tube diameter has increased

Resistance to flow offered by a fluid in motion describes

viscosity

Sound reflects totally at the wall-blood boundary once the doppler angle is less than ____ degrees

Spectral broadening may be produced by

beam spreading in arrays

The doppler equation relates the doppler shift to the

flow speed and frequency

the amount of blood passing a point per unit of time defines

volumetric flow rate

The angle of incidence is not important with which doppler display>

power

The decreased pressure is regions of high flow speed is called

Bernoulli effect

The difference between the emitted frequency and the echo frequency returning from a moving scatter is called the

Doppler shift

The fast fourier transform derives the Doppler

spectrum

The horizontal presentation in the spectral display represents

time

The resistance of the _____ accounts for about one half of the total resistance in the systemic circulation.

arterioles

The volumetric flow rate is equal to _____

average flow rate across the vessel multiplied by the cross sectional area of the vessel

The width of the sample volume is determined by the

beam width and sample volume depth

Turbulent flow is a form of _____ flow

nonlaminar

Variance color maps demonstate a change of hues from _____

left to right

Vertical thickening of spectral tracing is called

spectral broadening

What advantage does spectral analysis have when compared to other doppler techniques

spectral analysis displays peak systolic velocities

what is required for flow to occur

pressure difference

what is the driving force behind blood flow

pressure

what type of blood flow demonstrates layers of fluid sliding over each other?

laminar

Which flow type demonstrates a flow velocity that is essentially constant across the vessel

plug

which matter is considered fluid

gases and liquids

What Doppler display cannot determine flow direction?

power

What doppler technique must be time shared

Duplex imaging

What is an advantage of pulsed Doppler

depth of sample volume can be accurately selected

What pulsed doppler technique is most likely to demonstrate slow flow velocities in deep vessels?

power doppler

Which system control eliminates low-frequency doppler shifts

wall filter

Which type of blood flow demonstrates a chaotic flow pattern?

turbulent

Which type of blood flow would demonstrate the narrowest range of doppler shift frequencies?

plug

With color doppler imaging, the priority control _____

selects which gray-scale echo strength will demonstrate color

_____ describes the volumetric flow rate as a constant

Continuity rule

An imaginary laser thin transmitted ultrasound beam that can be thought of as producing excellent detail resolution throughout the image describes a _____

virtual transmission beam

The retrospective beam forming process occurs in the

image former

What contributes to improved temporal resolution in Principle 2?

fewer pulses and broad physical beams

What type of blood flow demonstrates layers of fluid sliding over each other

laminar

resistance of the blood flow depends on the radius of the

tube to the fourth power

if pressure difference in a straight vessel increase, the flow rate

increases

Tiniest vessels in the human body

capillaries

the state of the downstream arterioles is reflected in the

arterial diastolic flow

For a given flow, the greater the doppler angle, the less the

doppler shift

The maximum normal flow speed in the circulation is

100 cm/s

Variance color maps demonstrate a change of hues from

left to right

which system control eliminates low frequency doppler shifts

wall filter

the width of the sample volume is determined by the

beam width and sample volume depth

the horizontal presentation in the spectral display represents

time

spectral broadening may be produced by

beam spreading arrays

continuous wave doppler shifts are detected within the

overlapped region of the transmitting and receiving beams

the normal adult circulatory system contains ____ of blood

In a stenosis, flow speed increases and pressure

decreases

The doppler shift is proportional to the

blood flow speed

volumetric flow rate is proportional to

flow resistance

if the pressure difference between two point increases, the flow rate

also increases

Blood flows from the left and right ventricles into the _____ and _____ respectively

aorta pulmonary artery

According to Poiseuille's equation, if the radius of the tube increases, the flow rate

increases

If the flow speed increases, the pressure

decreases

Higher operating frequencies produce ____ doppler shifts

larger

If viscosity increases, flow rate

decreases

Increased flow speed through a stenosis can cause

distal turbulence

Multiple transmission focuses are used in

Principle 1

What contributes to improved temporal resolution in principle 2

fewer pulses broad physical beams

The retrospective beam forming process occurs in the

image former

Physical ultrasound beam forming is required in

both principle 1 and principle 2

Weakly focused or unfocused ultrasound beams are characteristic of

principle 2

The characteristic of fluid that offers resistance to flow is called

viscosisty

Flow is a response to pressure ______ or ______

difference gradient

If pressure difference is doubled, volumetric flow rate is _______

doubled

If flow rate is doubled, volumetric flow rate is

halved

Flow resistance in a vessel depends on

vessel length vessel radius blood viscosity

if operating frequency is doubled, the doppler shift is

doubled

if flow rate is doubled, the doppler shift is

doubled

Color doppler instruments use an ______ technique to yield doppler information in real time

autocorrelation

In practice, approximately _____ pulses are required to obtain one line of color-doppler information

color map baselines are always represented by

black

doubling the width of a color window produces a ____ frame rate

halved

Color doppler frame rates are ______ gray scale rates

less than

Doppler power imaging indicates (with color) the _____ of flow

presence

Stenosis affects

spectral broadening

Virtual beam forming applies to

Principle 2

Multiple transmission focus control applies to

Principle 1

Retrospective beam forming applies to

Principle 2

Improving a detail resolution sacrifices temporal resolution is true for

principle 1

Simultaneous gray scale, color doppler, and spectral doppler applies to

Principle 2

Principle 1 employs mostly

focused ultrasound beams

Reception focus principle applies to

both principle 1 and principle 2