Hussain Basheer
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Medical Physics Quiz on Physical basis of Doppler ultrasound imaging - Medical Physics - MCQs, created by Hussain Basheer on 23/11/2018.

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Physical basis of Doppler ultrasound imaging - Medical Physics - MCQs

Physical basis of Doppler ultrasound imaging - Medical Physics - MCQs

Question 1 of 33

1

Doppler shift applies to:

Select one of the following:

  • All wave phenomena

  • Ultrasound

  • Infrared EM waves

Explanation

Question 2 of 33

1

The contact gel used in ultrasonography (echography) is for:

Select one of the following:

  • Protection of the body from harmful ultrasound

  • Efficient transmission of sound waves into the tissue

  • Improvement of skin elasticity in the area of study

Explanation

Question 3 of 33

1

In medical imaging, Doppler echography is most appropriate for:

Select one of the following:

  • Deep body targets

  • Moving body targets

  • Surface targets

Explanation

Question 4 of 33

1

Which of the following waves do cannot propagate in vacuum?

Select one of the following:

  • Radiowaves

  • X-rays

  • Ultrasound

Explanation

Question 5 of 33

1

In what form is the information received with Doppler Echography displayed?

Select one of the following:

  • By sound

  • By one dimensional image

  • By two dimensional image with artificial coloring

Explanation

Question 6 of 33

1

Doppler frequency (shift) is:

Select one of the following:

  • The infrared spectrum of light, studied by Doppler

  • The frequency generated by ultrasonic transducer

  • The difference between emitted and reflected (received) frequency between to objects in relative motion.

Explanation

Question 7 of 33

1

For which of the following numerical Doppler frequency shifts is the blood speed the highest?

Select one of the following:

  • 1210 Hz

  • 800 Hz

  • 1530 Hz

Explanation

Question 8 of 33

1

Is it possible to tell the direction of motion of erythrocytes from the sign of the Doppler shift Δf = f - f0?

Select one of the following:

  • Yes, when Δf > 0 erythrocytes move towards the transducer

  • Yes, when Δf > 0erythrocytes move away from the transducer

  • No, the sign of Δf does not tell the direction of motion

Explanation

Question 9 of 33

1

If shorter wavelengths of ultrasound are less penetrating in human tissue, then which of the following frequencies is most appropriate for DEEP tissue and organ imaging?

Select one of the following:

  • 8 MHz

  • 3 MHz

  • 20 MHz

Explanation

Question 10 of 33

1

Doppler shift is defined as:

Select one of the following:

  • The frequency difference between emitted and received signals for observers at relative motion

  • The difference in acoustic impedance between two transmitting mediums

  • The intensity difference between emitted and reflected waves

Explanation

Question 11 of 33

1

At what angle (Θ) to the surface of the body should the ultrasonic probe be applied in order to gain a maximum Doppler shift? Consider that Doppler shift is proportional to cos (Θ).

Select one of the following:

  • Θ = 45⁰ (cos 45 = 0.7)

  • Θ = 90⁰ (cos 90 = 0)

  • Θ = 60⁰ (cos 60 = 0.5)

Explanation

Question 12 of 33

1

The speed of ultrasound in human tissue depends on:

Select one of the following:

  • The properties of the tissue

  • The properties of the apparatus

  • The speed of (ultra)sound does not depend on the tissue

Explanation

Question 13 of 33

1

The so called “reverse piezoelectric effect” finds application in:

Select one of the following:

  • Ultrasound generation

  • X-ray tubes

  • Lasers

Explanation

Question 14 of 33

1

Ultrasound can propagate through:

Select one of the following:

  • Vacuum

  • Matter

  • Everywhere where light propagates

Explanation

Question 15 of 33

1

Phonophoresis is:

Select one of the following:

  • Therapeutic application of ultrasound

  • Diagnostic application of ultrasound

  • Method for sterilization

Explanation

Question 16 of 33

1

Infrasound of certain frequency and intensity can:

Select one of the following:

  • Damage internal organs

  • Increase temperature of tissues

  • Rearrange water molecules

Explanation

Question 17 of 33

1

Infrasound CANNOT propagate through:

Select one of the following:

  • Soft tissue

  • Bones

  • Vacuum

Explanation

Question 18 of 33

1

Choose the correct statement:

Select one of the following:

  • Ultrasound is completely harmless for humans and animals

  • Sound reflection depends on the transparency of the medium

  • Sound impedance does not depend on frequency (for linear mediums)

Explanation

Question 19 of 33

1

Choose the correct range:

Select one of the following:

  • Audible sound: 103 Hz—106 Hz

  • Infrasound: 3 Hz—10 Hz

  • Ultrasound: 10 kHz—10 kHz

Explanation

Question 20 of 33

1

The resonant frequency of the vestibular system is in the range of:

Select one of the following:

  • Ultrasound

  • Infrasound

  • Ultraviolet

Explanation

Question 21 of 33

1

The direct piezoelectric effect is used for:

Select one of the following:

  • Ultrasound detectors

  • Ultrasound generators

  • Electrophoresis

Explanation

Question 22 of 33

1

Piezoelectric effect is defined as:

Select one of the following:

  • Electric polarization of solids under mechanical stress

  • Electro-mechanical coupling of objects falling off the tower of Pisa

  • Electric polarization in a solid due to temperature gradient.

Explanation

Question 23 of 33

1

Does human tissue exhibit piezoelectric properties?

Select one of the following:

  • No, the human body exhibits only capacitive properties

  • No, piezoelectric properties are observed in inorganic crystals

  • Yes, tissue such a collagen has piezoelectric properties

Explanation

Question 24 of 33

1

Which statement is correct?

Select one of the following:

  • The size of the ultrasonic equipment (echograph) influences the acoustic density of imaged tissue.

  • The precision of the ultrasonic instrument does not have an effect on the quality of received images

  • The ultrasonic image, displayed on the monitor, represents the acoustic density of studied tissues.

Explanation

Question 25 of 33

1

Mechanical waves with frequency above 20 kHz are called:

Select one of the following:

  • Infrasound

  • Ultrasound

  • P-waves

Explanation

Question 26 of 33

1

Infrasound is:

Select one of the following:

  • Electromagnetic waves with frequency under 20 Hz

  • Mechanical waves with frequency above 20 Hz

  • None of the above

Explanation

Question 27 of 33

1

If Δf is the change in frequency between emitted and received ultrasound signals due to Doppler effect during measurement of the linear speed of blood, then:

Select one of the following:

  • The speed of blood relative to the stationary transducer (emitter and receiver) is as much great as Δf is greater

  • Blood motion does not affect Δf

  • The speed of blood relative to the stationary transducer is greater when Δf is smaller.

Explanation

Question 28 of 33

1

Which natural science studies infrasound?

Select one of the following:

  • Pediatrics

  • Seismology

  • Dental medicine

Explanation

Question 29 of 33

1

Mechanical waves used for destruction of kidney stones, in procedure called “lithotripsy”, cause minimal damage to surrounding tissues because:

Select one of the following:

  • Mechanical waves do not propagate through the surrounding tissue

  • Acoustic pressure in the surrounding tissue is greatly reduced compared tothe pressure induced in the kidney stones

  • Mechanical waves do not have negative effect on soft tissue

Explanation

Question 30 of 33

1

Ultrasound waves propagate through human tissue as:

Select one of the following:

  • Longitudinal waves

  • Transverse waves

  • Both, longitudinal and transverse modes

Explanation

Question 31 of 33

1

Can humans sense infrasound waves?

Select one of the following:

  • Only when the intensity of the wave is sufficiently high for the ear to detect

  • No, that’s why they are called infra-sound

  • They can be sensed as vibrations by the tactile receptors of the skin

Explanation

Question 32 of 33

1

The resonant frequency of the internal organs is in the range of:

Select one of the following:

  • 10 MHz

  • Infrasound

  • Ultrasound

Explanation

Question 33 of 33

1

Which of the following is used in Doppler echography?

Select one of the following:

  • Magnetic resonance

  • Vacuum tubes

  • Piezoelectric effect

Explanation

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