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Ultrasound physics - Book questions > Elementary principlea (6-10%) > Flashcards

Elementary principlea (6-10%) Flashcards

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1
Q

If sound of 3 MHZ , 5 MHz and 10 MHz are transmitted through the same section of liver, reflections from which frequency would reach the transducer first ?

a. 3 MHz
b. 5MHz
c. 10 MHz
d. Reflection from all three frequencies would have identical times
e. It is not possible to predict which will arrive first

A

d

b/c speed propagation is not frequency dependent only det. by medium

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2
Q

You are scanning a patient with suspected gallstones using a 3.5 MHz transducer. You do not detect shadowing distal to the suspected gallstone. What can you do to enhance visibility of the acoustic shadow distal to a gallstone ?

a. increase the receiver gain
b. increase the acoustic power
c. increase the transducer frequency
d. increase the dynamic range
e. increase the frame rate

A

c.

because sound beam cannot be wider than stone (if it is, a portion of the beam on either side of the stone will be transmitted and send reflections from adjacents tissues = diminishing shadow

  • Focusing the sound beam and higher F are 2 methods to reduce B.W
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3
Q

During performance of an obstetrical ultrasound exam, you decide to adjust the system parameters to improve image . Which of the following parameters is NOT adjustable by operation control on the ultrasound system ?

a. Frequency
b. Propagation speed
c. Power
d. Intensity
e. Echo signal amplification

A

b

propagation speed is det. by medium only.

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4
Q 
You have completed a Doppler study of the renal arteries and found that the flow in the right renal artery is 3m/s. 
this measurement is equal to: 
a. .03 cm/s 
b. 0.3 cm/s 
c. 3 cm/s 
d. 30 cm/s 
e. 300 cm/s
A

e

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5
Q

You have been asked to perform an abdominal u/s exam of a thin female weighing approx 120 lbs. Which transducer would most likely yield the best compromise between spatial resolution and penetration for the study ?

a. 10 MHz
b. 15 MHz
c. 5 MHz
d. 3.5 MHZ
e. 2.5 MHZ

A

c.

a - b –> provide excellent spatial reso but poor penetration

d - e –> would provide excellent penetration but poor spatial res

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6
Q

Increasing the frequency on a multifrequency transducer from 3.5 - 5 MHz will :

a. increase the sound propagation speed
b. increase the pulse length
c. increase the penetration
d. Decrease the PRF
e. Decrease Wavelength

A

e.

because as F goes up , wavelength goes down

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7
Q 
You have increased the transmit power while performing a pelvic ultrasound.
This action increase the following : 
a. Penetration
b. Acoustic power
c. Image brightness
d. Voltage applied to crystals 
e. All of the above
A

e

a greater voltage is applied to the crystals, which increases sound energy transmitted to body

high penetration and high brightness of images

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8
Q

Which of the following is true regarding the half value layer (HVL) thickness for 10 MHz transducer in soft tissue ?

a. it represents a 3dB decrease in signal intensity
b. it occurs at a shallower depth than the HVL for a 5MHZ transducer
c. It represents the point at which the beam intensity is reduced by 1/2
d. B and C only
e. A, B , C

A

e

Half value layer = 1/2 of thickness of transducer

High Frequency = low HVL = low penetration

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9
Q

For distance measurements to be accurate in a U/S tissue phantom, the phantom sound propagation speed must be:

a. 13 us/cm
b. 1.54 m/s
c. 1540 m/s
d. 1/2 the speed of sound in tissue
e. Twice the speed of sound in soft tissue

A

c

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10
Q

For pulsed U/S , the following factor(s) determine the frequency of sound wave:

a. PRF
b. propagation speed of the piezoelectric material
c. Thickness of the piezoelectric material
d. B &C
e. A, B , C

A

d

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11
Q

While performing an U/S of the thyroid gland, you adjust the acoustic power by -3dB. Which of the following most accurately describes this adjustment ?

a. The intensity has been quadrupled
b. the intensity has been quartered
c. the intensity has been increased 10x
d. the intensity has been halved
e. the intensity has not been altered

A

d

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12
Q

Which of the following describes sound propagation through a vacuum ?

a. Sound travels as transverse waves through a vacuum
b. When a sound travels through a vacuum, the propagation speed increases to 3,300,00 m/s
c. Sounds travels at the speed of light when coursing through a vacuum
d. Sound propagation is random in a vacuum
e. Sound cannot travel through a vacuum

A

e

Sounds requires a medium to propagate

The physical movement of particles within a medium transport the sound

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13
Q

When your patient asks how much longer the U/S test will take, his voice is in the audible frequency range. Which of the following frequencies is in the audible frequency range?

a. 100 MHz
b. 10 kHZ
c. 10 Hz
d. 10,000 MHZ
e. 1,000,000 Hz

A

c

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14
Q

The maximum cyclical change in a quantity is known as :

a. amplitude
b. pressure
c. power
d. intensity
e. Decibel

A

a

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15
Q

Bulk modulus refers to which of the following qualities ?

a. propagation speed
b. Elasticity
c. wavelength
d. volume
e. stiffness

A

e

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16
Q

Which most correctly describes sounds propagation in a medium ?

a. in sound propagation, a molecule travels from one end of the medium to another
b. a molecule oscillates back and forth to propagate sound wave but does not move from one end of the medium to another
c. A molecule does not vary its position as a sound wave travels
d. Each molecule expands and contract to propagate a sound wave through a medium
e. Sound waves cannot travel through a medium

A

b

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17
Q

Which of the following terms denotes the time it takes for one cycle to occur ?

a. Frequency
b. Amplitude
c. Wavelength
d. Period
e. Pressure

A

d

18
Q

IF the number of cycles in a pulse is increased but the wavelength remains the same, which of the following is true?

a. The frequency is increased
b. The propagation speed is increased
c. The pulse duration is increased
d. The period is decreased
e. The bulk modulus is decreased

A

c

P.D is the time it takes to complete 1 pulse

19
Q

The following adjustment would decrease beam intensity

a. increasing acoustic output
b. decreasing receiver gain
c. increasing focusing
d. increasing the beam area
e. increasing amplitude

A

d

power = intensity / beam area

20
Q

Which of the following describes an u/s wave in human tissue ?

a. Mechanical longitudinal wave
b. Radioactive wave
c. Transverse rarefactional wave
d. Electromagnetic wave
e. Electromagnetic piezoelectric wave

A

a

21
Q

The regions of low pressure and density that are formed during sound propagation are termed:

a. Compression
b. Shear waves
c. Rarefractions
d. cavitation
e. bulk modulus

A

c

22
Q

The sound propagation speed used to calibrate range -measuring circuits on diagnostic u/s instruments is “

a. 1.54 m/s
b. 1560 mm/s
c. 1.46 mm/us
d. 1540 m/s
e. 146000 cm/s

A

d

23
Q

Which of the following properties would result in increased propagation speed of a medium ?

a/ increased stiffness

b. increased density
c. increased frequency
d. increased distance
e. increased amplitude

A

a

propagation speed = bulk modulus/ density

24
Q

Which of the following frequencies is considered to be u/s ?

a. 2000 Hz
b. 20 Hz
c. 2 MHz
d. 200 Hz
e . 2 Hz

A

c

25
Q

Which of the following increases as frequency increases ?

a. absorption
]b. Scattering 
c. Attenuation 
d. A & C 
e. All of the above
A

e

26
Q

Which statement about the 2 pulse trains displayed below is true ?

a. A has a higher frequency than B
b. B has a shorter period than A
c. A has a shorter wavelength than B
d. A has better axial resolution than B
e. B has a greater SPL than A

A

b

27
Q

While performing a hepatic sonogram with a fatty liver, you are unable to visualize the posterior right lobe of the liver. WHich of the following solutions would be most likely to enable visualization of this area ?

a. decrease dynamic range
b. decrease near field DGC
c. Choose a lower frequency transducer
d. increases the scan line density
e. change the gray scale map

A

c

28
Q

What is the velocity of an U/S wave in bone ?

a. 333 m/s
b. 8050 m/s
c. 1540 m/s
d. 4080 m/s
e. 1240 m/s

A

d

29
Q

The speed of sound is defined as the :

a. Speed of the vibrating particles in the medium
b. Speed at which the sound wave propagates through the medium
c. Number of cycles per second of the vibrating particles
d. inverse of the frequency
e. Speed of the electrical impulse applied to the piezoelectric element

A

b

30
Q

A longitudinal wave is characterized by :

a. A wave that demonstrates only sagittal imaging planes
b. Randomized particle motion
c. A constant acoustic velocity of 1540 m/s
d. Particle motion occurring in the same direction as propagation
e. Particle motion occurring perpendicular to the direction of propagation

A

d

31
Q

A longitudinal wave is characterized by :

a. A wave that demonstrates only sagittal imaging planes
b. Randomized particle motion
c. A constant acoustic velocity of 1540 m/s
d. Particle motion occurring in the same direction as propagation
e. Particle motion occurring perpendicular to the direction of propagation

A

d

32
Q

The renal cyst you are imaging measure 35 mm. This value can also be expressed as :

a. 350 cm
b. 0.35 cm
c. 3.5 cm
d. 35 m
e. 3.5 m

A

c

33
Q

Relative measurement of intensity based on a logarithmic scale is expressed in:

a. Newtons per centimeter squared 
b, Watts per centimer squared
c. decibels 
d. Pascals 
e. Neper
A

c

34
Q

Which prefix equals 10 ^-3

a. micro
b. milli
c. mega
d. centi
e. none of the above

A

b

35
Q

Frequency of the U/S wave is defined as

a. speed of the vibrating particles in the medium
b. speed at which sound wave propagates through the medium
c. number of cycles per second
d. inverse of the wavelength
e. number of electrical impulse applied to the transducer per second

A

c

36
Q

While performing a Doppler U/S exam, you notice that the PRF on the display read 13 kHz. This can also be expressed as :

a. 0.35 Hz
b. 1300 Hz
c. 1.3 MHZ
d. 13,000 Hz
e. 130 MHz

A

d

37
Q

In sound wave propagation, the region of elevated pressure is termed :

a. compression
b. Demodulation
c. Rarefaction
d. Period
e. Resonance

A

A

38
Q

When you switch from a 2.5 MHz to 5 MHz transducer, the sound wavelength

a. Doubles
b. Quadruples
c. Halves
d. Quarters
e. is unaffected

A

c

39
Q

The period of 5 MHz frequency is ?

a. 0.02 s
b. 0.002 s
c. 0.00002s
d. 0.000002 s
e. 0.0000002 s

A

e

40
Q

Wavelength depends on what 2 factors ?

a. Frequency and amplitude
b. Amplitude and propagation speed
c. Period and frequency
d. Frequency and propagation speed
e. Amplitude and intensity

A

d

Ultrasound physics - Book questions (11 decks)

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