Chapter 5 - Doppler Principles

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Chapter 5 - Doppler Principles - Quiz

Questions and Answers
  • 1. 

    Which of the following are parts of the circulatory system?

    • A.

      Heart

    • B.

      Cerebral Ventricle

    • C.

      Artery

    • D.

      Arteriole

    • E.

      Capillary

    • F.

      Bile Duct

    • G.

      Venule

    • H.

      Vein

    Correct Answer(s)
    A. Heart
    C. Artery
    D. Arteriole
    E. Capillary
    G. Venule
    H. Vein
    Explanation
    The circulatory system consists of the heart, arteries, arterioles, capillaries, venules, and veins. The heart pumps blood throughout the body, while arteries carry oxygenated blood away from the heart to the organs and tissues. Arterioles are smaller branches of arteries that help regulate blood flow. Capillaries are tiny blood vessels where oxygen and nutrients are exchanged with waste products. Venules collect blood from the capillaries and carry it to the veins. Veins return deoxygenated blood back to the heart.

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  • 2. 

    The _____ are the tiniest vessles in the circulatory system?

    • A.

      Vein

    • B.

      Capillaries

    • C.

      Arteries

    Correct Answer
    B. Capillaries
    Explanation
    Capillaries are the tiniest vessels in the circulatory system. They are responsible for the exchange of oxygen, nutrients, and waste products between the blood and the surrounding tissues. Capillaries have thin walls that allow for the diffusion of substances, and their large surface area facilitates efficient exchange. Unlike veins and arteries, which have thicker walls and carry blood to and from the heart, capillaries are the site of exchange and connect the smallest arteries (arterioles) to the smallest veins (venules).

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  • 3. 

    In which of the following can Doppler ultrasound detect flow?

    • A.

      Heart

    • B.

      Arteries

    • C.

      Arterioles

    • D.

      Capillaries

    • E.

      Venules

    • F.

      Veins

    Correct Answer(s)
    A. Heart
    B. Arteries
    F. Veins
    Explanation
    Doppler ultrasound can detect flow in the heart, arteries, and veins. Doppler ultrasound uses sound waves to measure the speed and direction of blood flow. It can be used to assess blood flow in the heart, such as detecting abnormal blood flow patterns or blockages in the coronary arteries. It can also be used to evaluate blood flow in the arteries and veins of the body, helping to diagnose conditions such as peripheral artery disease or deep vein thrombosis.

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  • 4. 

    To flow is to move in a ______.

    • A.

      Direction

    • B.

      Pattern

    • C.

      Stream

    Correct Answer
    C. Stream
    Explanation
    To flow is to move in a stream.

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  • 5. 

    The characteristic of a fluid that offers resistance to flow is called?

    • A.

      Resistance

    • B.

      Viscosity

    • C.

      Inertia

    • D.

      Impedance

    • E.

      Density

    Correct Answer
    B. Viscosity
    Explanation
    Viscosity is the correct answer because it refers to the characteristic of a fluid that offers resistance to flow. It is a measure of the internal friction within a fluid, and it determines how easily the fluid can flow. A higher viscosity means a thicker, more resistant fluid, while a lower viscosity means a thinner, more easily flowing fluid.

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  • 6. 

    Poise is a unit of

    • A.

      Visocity

    • B.

      Friction

    • C.

      Inertia

    Correct Answer
    A. Visocity
    Explanation
    The correct answer is viscosity. Viscosity is a measure of a fluid's resistance to flow. It is a property of fluids that determines how easily they flow and how much they resist deformation. Poise is the unit used to measure viscosity, named after French physician Jean Louis Marie Poiseuille.

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  • 7. 

    Pressure is ______ per unit area.

    • A.

      Force

    • B.

      Fricition

    • C.

      Liquid

    Correct Answer
    A. Force
    Explanation
    Pressure is defined as the force exerted per unit area. In other words, it is the amount of force applied over a given area. Therefore, the correct answer is force.

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  • 8. 

    If the pressure is greater at one end of the liquid-filled tube or vessle than it is at the other, the liquid will flow from the _____ pressure and to the _____ pressure end.

    • A.

      Higher, lower

    • B.

      Lower, higher

    • C.

      Depends on the liquid

    • D.

      All of the above

    • E.

      None of the above

    Correct Answer
    A. Higher, lower
    Explanation
    When the pressure is greater at one end of the liquid-filled tube or vessel than at the other, the liquid will flow from the higher pressure end to the lower pressure end. This is because fluids always flow from areas of higher pressure to areas of lower pressure, following the path of least resistance. Therefore, the correct answer is "higher, lower".

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  • 9. 

    Flow increases if _____ increase(s).

    • A.

      Pressure difference

    • B.

      Pressure gradient

    • C.

      Resistance

    • D.

      A and B

    • E.

      All of the above

    Correct Answer
    D. A and B
    Explanation
    Flow increases if both pressure difference and pressure gradient increase. When there is a greater pressure difference between two points, there is a higher driving force pushing the fluid through a system, resulting in increased flow. Similarly, a steeper pressure gradient indicates a greater change in pressure over a given distance, leading to increased flow. Therefore, both A (pressure difference) and B (pressure gradient) are correct explanations for the increase in flow.

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  • 10. 

    As flow resistance increases, volumetic flow rate will

    • A.

      Increase

    • B.

      Decrease

    • C.

      Stay the same

    Correct Answer
    B. Decrease
    Explanation
    As flow resistance increases, it creates more obstacles for the fluid to flow through, resulting in a decrease in the volumetric flow rate. This is because the increased resistance causes a higher pressure drop across the system, reducing the flow velocity and ultimately decreasing the amount of fluid passing through per unit time.

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  • 11. 

    If pressure difference is doubled, volumetric flow rate is

    • A.

      Unchanged

    • B.

      Quartered

    • C.

      Halved

    • D.

      Doubled

    • E.

      Quadrupled

    Correct Answer
    D. Doubled
    Explanation
    When the pressure difference is doubled, the volumetric flow rate also doubles. This is because according to Bernoulli's principle, an increase in pressure difference leads to an increase in fluid velocity. As a result, the fluid flows through the system at a faster rate, causing the volumetric flow rate to double.

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  • 12. 

    If flow resistance is doubled, volumetric flow rate is

    • A.

      Unchanged

    • B.

      Quartered

    • C.

      Halved

    • D.

      Doubled

    • E.

      Quadrupled

    Correct Answer
    C. Halved
    Explanation
    If the flow resistance is doubled, it means that it becomes harder for the fluid to flow through the system. This increased resistance will result in a decrease in the volumetric flow rate. Therefore, the correct answer is "halved," indicating that the flow rate will be reduced by half.

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  • 13. 

    Flow resistance in a vessel depends on _______.

    • A.

      Vessel length

    • B.

      Vessel radius

    • C.

      Blood viscosity

    • D.

      All of the above

    • E.

      None of the above

    Correct Answer
    D. All of the above
    Explanation
    The correct answer is "all of the above". Flow resistance in a vessel depends on all of the given factors - vessel length, vessel radius, and blood viscosity. Vessel length affects resistance because the longer the vessel, the more frictional resistance there is to blood flow. Vessel radius also affects resistance because a smaller radius leads to increased resistance. Blood viscosity, which refers to the thickness or stickiness of the blood, also affects resistance as thicker blood has higher resistance. Therefore, all of these factors contribute to flow resistance in a vessel.

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  • 14. 

    Flow resistance decreases with an increase in ______.

    • A.

      Svessel length

    • B.

      Vessel radius

    • C.

      Blood viscosity

    • D.

      All of the above

    • E.

      None of the above

    Correct Answer
    B. Vessel radius
    Explanation
    The correct answer is vessel radius. Flow resistance is directly proportional to vessel length and inversely proportional to vessel radius. As the vessel radius increases, the flow resistance decreases because there is more space for the blood to flow through, resulting in a lower resistance to flow. Conversely, if the vessel radius decreases, the flow resistance increases. Blood viscosity also affects flow resistance, but it is not the only factor that can cause a decrease in flow resistance.

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  • 15. 

    Flow resistance depends most strongly on ____.

    • A.

      Vessel length

    • B.

      Vessel radius

    • C.

      Blood viscosity

    • D.

      All of the above

    • E.

      None of the above

    Correct Answer
    B. Vessel radius
    Explanation
    The flow resistance in a vessel is determined by various factors, but the most significant one is the vessel radius. As the radius of the vessel decreases, the flow resistance increases exponentially. This is because a smaller radius leads to a smaller cross-sectional area, resulting in a higher velocity of blood flow and increased frictional forces between the blood and the vessel walls. Therefore, vessel radius has the strongest influence on flow resistance.

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  • 16. 

    Volumetric flow rate decreases with an increase in ____.

    • A.

      Pressure difference

    • B.

      Vessel radius

    • C.

      Vessel length

    • D.

      Blood viscosity

    • E.

      C and d

    Correct Answer
    E. C and d
    Explanation
    The volumetric flow rate refers to the volume of fluid that passes through a given point in a unit of time. According to the question, the volumetric flow rate decreases with an increase in vessel length and blood viscosity. This means that as the length of the vessel increases or the viscosity of the blood increases, the flow rate of the fluid decreases. This can be explained by the fact that longer vessels and more viscous fluids create more resistance to the flow, resulting in a decrease in flow rate.

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  • 17. 

    When the speed of a fluid is constant across a vessel, the flow is called _____ flow.

    • A.

      Volume

    • B.

      Parabolic

    • C.

      Laminar

    • D.

      Viscous

    • E.

      Plug

    Correct Answer
    E. Plug
    Explanation
    In plug flow, the speed of the fluid remains constant across the vessel. This means that the fluid flows in a uniform manner without any disturbances or mixing. It is characterized by a cylindrical or plug-like flow profile, where the fluid elements move in parallel layers without any radial mixing. This type of flow is commonly observed in certain industrial processes and can be advantageous for maintaining consistent conditions within the vessel.

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  • 18. 

    __________ flow occurs wen straight parallel streamlines describing the flow are altered.

    • A.

      Disturbed

    • B.

      Turbulent

    • C.

      Plug

    • D.

      Viscous

    Correct Answer
    A. Disturbed
    Explanation
    Disturbed flow occurs when straight parallel streamlines describing the flow are altered. This means that the flow pattern is no longer smooth and regular, but instead becomes irregular and chaotic. This can be caused by various factors such as obstacles in the flow, changes in velocity or pressure, or the presence of turbulence. In disturbed flow, the streamlines may become curved, twisted, or broken, indicating a disruption in the flow pattern.

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  • 19. 

    _____________ flow involves random and chaotic flow patterns, with particles flowing in all directions.

    • A.

      Disturbed

    • B.

      Turbulent

    • C.

      Plug

    • D.

      Viscous

    Correct Answer
    B. Turbulent
    Explanation
    Turbulent flow involves random and chaotic flow patterns, with particles flowing in all directions. It is characterized by irregular fluctuations in velocity and pressure, resulting in mixing and diffusion of particles. In turbulent flow, the fluid moves in eddies and swirls, causing a high level of mixing and energy dissipation. This type of flow is commonly observed in situations where there is high velocity, large pressure gradients, or irregular surfaces.

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  • 20. 

    Turbulent flow is more likely proximal or distal to a stenosis

    • A.

      Proximal

    • B.

      Distal

    Correct Answer
    B. Distal
    Explanation
    Turbulent flow is more likely to occur distal to a stenosis. This is because as blood flows through a narrowed or stenotic vessel, it experiences increased resistance, leading to changes in flow patterns. Distal to the stenosis, the blood flow is more likely to become turbulent due to the abrupt changes in vessel diameter and increased velocity. Proximal to the stenosis, the flow is more likely to be laminar as it has not yet encountered the resistance of the stenosis.

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  • 21. 

    A narrowing of the lumen of a tube is called a _________.

    • A.

      Stenosis

    • B.

      Pulsatile

    • C.

      Disturbed

    Correct Answer
    A. Stenosis
    Explanation
    A narrowing of the lumen of a tube is called stenosis. Stenosis refers to the abnormal narrowing of a tubular structure, such as a blood vessel or a digestive tract. This narrowing can restrict the flow of fluids or substances through the tube, leading to various symptoms depending on the location and severity of the stenosis.

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  • 22. 

    Proximal to , at, and distal to a stenosis ________, must be constant.

    • A.

      Laminar flow

    • B.

      Disturbed flow

    • C.

      Turbulent flow

    • D.

      Volumetic flow rate

    • E.

      None of the above

    Correct Answer
    C. Turbulent flow
    Explanation
    The correct answer is turbulent flow. When there is a stenosis (narrowing) in a blood vessel, the flow of blood proximal to (before), at, and distal to (after) the stenosis becomes turbulent. Turbulent flow is characterized by chaotic and irregular flow patterns, with eddies and swirls. In contrast, laminar flow is smooth and orderly, while disturbed flow is a combination of both laminar and turbulent flow. Volumetric flow rate refers to the volume of fluid passing through a given area per unit of time and is not necessarily constant in the presence of a stenosis.

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  • 23. 

    Poiseuille's equation predicts a(n) ________ in flow speed with a decrease in vessel radius.  

    • A.

      Decrease

    • B.

      Increase

    Correct Answer
    A. Decrease
    Explanation
    According to Poiseuille's equation, there is an inverse relationship between flow speed and vessel radius. As the vessel radius decreases, the flow speed decreases. This is because a smaller radius creates more resistance to flow, resulting in a slower flow speed.

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  • 24. 

    In a stenosis, the pressure if _______ the proximal and distal values.

    • A.

      Less than

    • B.

      Equal to

    • C.

      Greater than

    • D.

      Depends on the fuild

    • E.

      None of the above

    Correct Answer
    A. Less than
    Explanation
    In a stenosis, the pressure is less than the proximal and distal values. This is because a stenosis is a narrowing or constriction in a blood vessel, which restricts the flow of blood. As a result, the pressure upstream (proximal) to the stenosis is higher, while the pressure downstream (distal) to the stenosis is lower. Therefore, the pressure in a stenosis is less than both the proximal and distal values.

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  • 25. 

    The _______ effect is used to detect and measure ________ in vessels.

    • A.

      Doppler, flow

    • B.

      Poiseuille's, velocity

    • C.

      Color, flow

    Correct Answer
    A. Doppler, flow
    Explanation
    The Doppler effect is used to detect and measure flow in vessels. The Doppler effect refers to the change in frequency or wavelength of a wave when there is relative motion between the source of the wave and the observer. In the context of blood flow in vessels, the Doppler effect is used to measure the velocity and direction of blood flow by analyzing the changes in frequency of the ultrasound waves reflected by the moving blood cells. Therefore, the correct answer is doppler, flow.

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  • 26. 

    Motion of an echo-generating structure causes an echo to have a different _______ from that of the emitted pulse.

    • A.

      Frequency

    • B.

      Period

    • C.

      Pulse duration

    Correct Answer
    A. Frequency
    Explanation
    When an echo is generated, it is caused by the motion of an echo-generating structure. This motion affects the frequency of the echo, causing it to be different from that of the emitted pulse. The frequency of a wave refers to the number of complete cycles it completes in a given time period. Therefore, the correct answer is frequency.

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  • 27. 

    If the incident frequency is 1 MHz, the propagation speed is 1600 m/s, and the reflector speed is 16 m/s toward the source, the Doppler shift is _________________ MHz.

    Correct Answer
    .02
    Explanation
    2 x 16 x1 / 1600 =
    32/1600 = .02

    2 x velocity x frequency / c

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  • 28. 

    If the incident frequency is 1 MHz, the propagation speed is 1600 m/s, and the reflector speed is 16 m/s toward the source, the reflected frequency is _____________ MHz.

    Correct Answer
    1.02
    Explanation
    1 MHz + .02 doppler shift

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  • 29. 

    If 2-MHz ultrasound is reflected from a soft tissue boundary moving at 10 m/s toward the source, the Doppler shift is ________ MHz.

    Correct Answer
    .026
    Explanation
    2 x velcoity (10) x f(2) / c (1540) = .026

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  • 30. 

    The doppler shift is the difference between  ______ and ______ frequencies

    • A.

      Emitted & received

    • B.

      Beginning & end

    • C.

      Continuous & listening

    Correct Answer
    A. Emitted & received
    Explanation
    The doppler shift is the difference between the frequencies of sound waves that are emitted and received. When an object emitting sound waves is in motion, the frequency of the waves appears higher to an observer in front of the object and lower to an observer behind the object. This shift in frequency is known as the doppler shift and is caused by the relative motion between the source of the sound waves and the observer.

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  • 31. 

    When incident sound direction and reflector motion are not parallel, calculation of the refelcted frequency involves the _______ of the angle btwn these directions

    • A.

      Cosine

    • B.

      Inside

    • C.

      Outside

    Correct Answer
    A. Cosine
    Explanation
    When incident sound direction and reflector motion are not parallel, the calculation of the reflected frequency involves the cosine of the angle between these directions. The cosine of an angle is a trigonometric function that relates the length of the adjacent side of a right triangle to the hypotenuse. In this context, it is used to determine the change in frequency of the reflected sound wave based on the angle between the incident sound direction and the motion of the reflector.

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  • 32. 

    For an operating frequency of 2 MHz, a flow speed of 10 cm/s, and a Doppler angle of 0 degrees, calcuate the Doppler Shift.

    Correct Answer
    .26 kHz
    Explanation
    Doppler Shift = 2 x V x Operating Frequency x cosine / c

    2(2)(10) / 1.540 = 25.9 = .26KHz

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  • 33. 

    For an operating frequency of  6 MHz, a flow speed of 50 cm/s, and a Doppler angle of 60 degrees, calculate the Doppler Shift.

    Correct Answer
    1.95 kHz
    Explanation
    Doppler Shift = 2 x V x Operating Frequency x cosine / c
    2(50)6(.50) / 1.540 = 194.8 = 1.95 kHz

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  • 34. 

    Which Doppler angle yields the greatest Doppler Shift?

    • A.

      -90

    • B.

      -45

    • C.

      0

    • D.

      45

    • E.

      90

    Correct Answer
    C. 0
    Explanation
    The Doppler angle of 0 degrees yields the greatest Doppler Shift. This is because at 0 degrees, the angle between the direction of the wave and the direction of motion of the source or observer is minimal, resulting in the maximum change in frequency. As the angle increases or decreases from 0 degrees, the Doppler Shift decreases.

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  • 35. 

    If operating frequency is doubled, the Doppler shift is

    • A.

      Half

    • B.

      Doubled

    • C.

      Quadrupled

    • D.

      Same

    Correct Answer
    B. Doubled
    Explanation
    When the operating frequency is doubled, the Doppler shift is also doubled. This is because the Doppler shift is directly proportional to the frequency of the wave. As the frequency increases, the change in frequency caused by the Doppler effect also increases. Therefore, when the operating frequency is doubled, the Doppler shift will also double.

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  • 36. 

    If flow speed is doubled, the Doppler shift is

    • A.

      Doubled

    • B.

      Quadrupled

    • C.

      Stays the same

    • D.

      Half

    Correct Answer
    A. Doubled
    Explanation
    When the flow speed is doubled, the Doppler shift also doubles. This is because the Doppler shift is directly proportional to the velocity of the source or observer relative to the medium through which the wave is traveling. Increasing the flow speed by a factor of 2 will result in a doubling of the Doppler shift.

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  • 37. 

    If Doppler angle is doubled, the doppler shift is

    • A.

      Decreased

    • B.

      Increased

    • C.

      Stays the same

    Correct Answer
    A. Decreased
    Explanation
    When the Doppler angle is doubled, it means that the angle between the direction of the wave and the direction of motion of the source or observer is increased. As a result, the component of the velocity along the line of sight decreases, leading to a decrease in the Doppler shift. Therefore, the correct answer is decreased.

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  • 38. 

    Which of the following on a color doppler display is (are) presented in real time?

    • A.

      Gray-scale anatomy

    • B.

      Flow direction

    • C.

      Doppler spectrum

    • D.

      A & B

    • E.

      All of the above

    Correct Answer
    D. A & B
    Explanation
    The gray-scale anatomy and flow direction on a color Doppler display are presented in real time. This means that the images and information displayed are continuously updated and reflect the current conditions and movements within the body. The Doppler spectrum, on the other hand, is not presented in real time as it is a graphical representation of the velocity of blood flow over time. Therefore, the correct answer is A & B.

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  • 39. 

    In color doppler instruments, color is used only to represent flow direction.

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    Color Doppler instruments use color to represent both flow direction and velocity. By assigning different colors to different flow directions (such as red for flow towards the transducer and blue for flow away from the transducer), the instrument provides a visual representation of the blood flow patterns. Additionally, the intensity or brightness of the color is used to represent the velocity of the blood flow, with brighter colors indicating higher velocities. Therefore, the statement that color is used only to represent flow direction is incorrect.

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  • 40. 

    The angle dependencies of Doppler shift displays and Doppler power displays are different.

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    Power display does not depend on an angle

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  • 41. 

    In practice, approximately ________ pulses are requried to obtain one line of color doppler information.

    • A.

      1

    • B.

      10

    • C.

      100

    • D.

      1000

    • E.

      1,000,000

    Correct Answer
    B. 10
    Explanation
    In practice, approximately 10 pulses are required to obtain one line of color Doppler information. This means that the ultrasound machine emits 10 pulses of sound waves and receives the echoes back from the tissues to create a single line of color Doppler image. This process is repeated multiple times to generate a complete color Doppler image.

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  • 42. 

    About  ________ frames per seocnd are produced by a color Doppler instrument.

    • A.

      10

    • B.

      20

    • C.

      40

    • D.

      80

    • E.

      More than one of the above

    Correct Answer
    E. More than one of the above
    Explanation
    The correct answer is "More than one of the above." The question is asking about the number of frames per second produced by a color Doppler instrument. Since the options provided are 10, 20, 40, 80, and "More than one of the above," it suggests that the instrument can produce a frame rate that is greater than 80 frames per second. Therefore, the correct answer is "More than one of the above."

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  • 43. 

    Doppler shift displays are not dependent on Doppler angle.

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    It is dependant on the angle

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  • 44. 

    If a color doppler instrument shows two colors in the same vessel, it always means flow is occuring in opposit directions in the vessels.

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    The statement is false because the presence of two colors in the same vessel on a color doppler instrument does not always indicate flow occurring in opposite directions. It could be due to other factors such as turbulence or aliasing. Therefore, the presence of two colors in the same vessel does not necessarily imply flow in opposite directions.

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  • 45. 

    A region of bright color on doppler shift display always indicates the highest flow speeds.

    • A.

      True

    • B.

      False

    Correct Answer
    B. False
    Explanation
    A region of bright color on a Doppler shift display does not always indicate the highest flow speeds. The brightness of the color in a Doppler shift display represents the strength or intensity of the signal, not necessarily the velocity or speed of the flow. The velocity of the flow is typically represented by the color itself, with different colors indicating different velocities. Therefore, a bright color region could indicate a strong signal but not necessarily the highest flow speeds.

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  • 46. 

    Increasing the ensemble length _______ the frame rate.

    • A.

      Increases

    • B.

      Decreases

    • C.

      Stays the same

    Correct Answer
    B. Decreases
    Explanation
    Increasing the ensemble length decreases the frame rate. This means that as the ensemble length, which refers to the number of individual frames in a sequence, increases, the frame rate, which is the number of frames displayed per second, decreases. This is because a longer ensemble length requires more time to process and display each frame, resulting in a slower frame rate.

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  • 47. 

    Which of the following reduce the frame rate of a color doppler image?

    • A.

      Wider color window

    • B.

      Longer color window

    • C.

      Increased ensemble length

    • D.

      Higher transducer frequency

    • E.

      Higher priority setting

    Correct Answer(s)
    A. Wider color window
    C. Increased ensemble length
    Explanation
    A wider color window reduces the frame rate of a color doppler image because it increases the amount of data that needs to be processed and displayed, which takes longer to complete. Similarly, an increased ensemble length also reduces the frame rate because it requires more time to collect and analyze the data from multiple pulses. These factors contribute to a slower frame rate, which may result in a less smooth and slower image display.

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  • 48. 

    Lack of color in a vessel containing blood flow may be attributable to ______.

    • A.

      Low color gain

    • B.

      A high wall filter setting

    • C.

      A low priority setting

    • D.

      Baseline shift

    • E.

      Aliasing

    Correct Answer(s)
    A. Low color gain
    B. A high wall filter setting
    C. A low priority setting
    Explanation
    The lack of color in a vessel containing blood flow may be attributable to low color gain, a high wall filter setting, or a low priority setting. Low color gain refers to a decrease in the intensity of color signals, resulting in a lack of color representation. A high wall filter setting can filter out low-frequency signals, including color signals, leading to a lack of color. A low priority setting may prioritize other imaging parameters over color representation, causing a lack of color in the vessel.

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  • 49. 

    Increasing ensemble length ________ color sensitivity and accuracy and ______ frame rate

    • A.

      Improves, increases

    • B.

      Degrades, increases

    • C.

      Degrades, decreases

    • D.

      Improves, decreases

    Correct Answer
    D. Improves, decreases
    Explanation
    Increasing ensemble length improves color sensitivity and accuracy, as more data from different sources can be combined to enhance the overall quality of the image. However, it decreases frame rate, as more time is required to process and combine the additional data, resulting in a slower refresh rate.

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  • 50. 

    Which control can be used to help with clutter?

    • A.

      Wall filter

    • B.

      Gain

    • C.

      Baseline shift

    • D.

      Pulse repetition frequency

    • E.

      Smoothing

    Correct Answer
    A. Wall filter
    Explanation
    The wall filter control can be used to help with clutter. The wall filter is a digital signal processing technique that removes low-frequency noise and clutter from ultrasound images. It filters out unwanted signals that may interfere with the clarity of the image, reducing clutter and improving image quality. By adjusting the wall filter control, the user can effectively manage and reduce clutter in the ultrasound image.

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