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Physical basis of Doppler ultrasound imaging - Medical Physics - MCQs

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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.
Hussain Basheer
Quiz by Hussain Basheer, updated more than 1 year ago
Hussain Basheer
Created by Hussain Basheer about 6 years ago
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Resource summary

Question 1

Question
Doppler shift applies to:
Answer
  • All wave phenomena
  • Ultrasound
  • Infrared EM waves

Question 2

Question
The contact gel used in ultrasonography (echography) is for:
Answer
  • Protection of the body from harmful ultrasound
  • Efficient transmission of sound waves into the tissue
  • Improvement of skin elasticity in the area of study

Question 3

Question
In medical imaging, Doppler echography is most appropriate for:
Answer
  • Deep body targets
  • Moving body targets
  • Surface targets

Question 4

Question
Which of the following waves do cannot propagate in vacuum?
Answer
  • Radiowaves
  • X-rays
  • Ultrasound

Question 5

Question
In what form is the information received with Doppler Echography displayed?
Answer
  • By sound
  • By one dimensional image
  • By two dimensional image with artificial coloring

Question 6

Question
Doppler frequency (shift) is:
Answer
  • 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.

Question 7

Question
For which of the following numerical Doppler frequency shifts is the blood speed the highest?
Answer
  • 1210 Hz
  • 800 Hz
  • 1530 Hz

Question 8

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

Question 9

Question
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?
Answer
  • 8 MHz
  • 3 MHz
  • 20 MHz

Question 10

Question
Doppler shift is defined as:
Answer
  • 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

Question 11

Question
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).
Answer
  • Θ = 45⁰ (cos 45 = 0.7)
  • Θ = 90⁰ (cos 90 = 0)
  • Θ = 60⁰ (cos 60 = 0.5)

Question 12

Question
The speed of ultrasound in human tissue depends on:
Answer
  • The properties of the tissue
  • The properties of the apparatus
  • The speed of (ultra)sound does not depend on the tissue

Question 13

Question
The so called “reverse piezoelectric effect” finds application in:
Answer
  • Ultrasound generation
  • X-ray tubes
  • Lasers

Question 14

Question
Ultrasound can propagate through:
Answer
  • Vacuum
  • Matter
  • Everywhere where light propagates

Question 15

Question
Phonophoresis is:
Answer
  • Therapeutic application of ultrasound
  • Diagnostic application of ultrasound
  • Method for sterilization

Question 16

Question
Infrasound of certain frequency and intensity can:
Answer
  • Damage internal organs
  • Increase temperature of tissues
  • Rearrange water molecules

Question 17

Question
Infrasound CANNOT propagate through:
Answer
  • Soft tissue
  • Bones
  • Vacuum

Question 18

Question
Choose the correct statement:
Answer
  • 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)

Question 19

Question
Choose the correct range:
Answer
  • Audible sound: 103 Hz—106 Hz
  • Infrasound: 3 Hz—10 Hz
  • Ultrasound: 10 kHz—10 kHz

Question 20

Question
The resonant frequency of the vestibular system is in the range of:
Answer
  • Ultrasound
  • Infrasound
  • Ultraviolet

Question 21

Question
The direct piezoelectric effect is used for:
Answer
  • Ultrasound detectors
  • Ultrasound generators
  • Electrophoresis

Question 22

Question
Piezoelectric effect is defined as:
Answer
  • 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.

Question 23

Question
Does human tissue exhibit piezoelectric properties?
Answer
  • No, the human body exhibits only capacitive properties
  • No, piezoelectric properties are observed in inorganic crystals
  • Yes, tissue such a collagen has piezoelectric properties

Question 24

Question
Which statement is correct?
Answer
  • 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.

Question 25

Question
Mechanical waves with frequency above 20 kHz are called:
Answer
  • Infrasound
  • Ultrasound
  • P-waves

Question 26

Question
Infrasound is:
Answer
  • Electromagnetic waves with frequency under 20 Hz
  • Mechanical waves with frequency above 20 Hz
  • None of the above

Question 27

Question
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:
Answer
  • 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.

Question 28

Question
Which natural science studies infrasound?
Answer
  • Pediatrics
  • Seismology
  • Dental medicine

Question 29

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

Question 30

Question
Ultrasound waves propagate through human tissue as:
Answer
  • Longitudinal waves
  • Transverse waves
  • Both, longitudinal and transverse modes

Question 31

Question
Can humans sense infrasound waves?
Answer
  • 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

Question 32

Question
The resonant frequency of the internal organs is in the range of:
Answer
  • 10 MHz
  • Infrasound
  • Ultrasound

Question 33

Question
Which of the following is used in Doppler echography?
Answer
  • Magnetic resonance
  • Vacuum tubes
  • Piezoelectric effect
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