Finals

Question 1

Sound waves are:
a. electric
b. mechanical, transverse
c. spectral
d. longitudinal, mechanical

Answer 1

longitudinal, mechanical

Question 2

The speed of US in soft tissue is closest to:
a. 1,540 km/sec
b. 1.54 km/msec
c. 1,500m/s
d. 1,540mm/sec

Question 3

The frequency closest to the lower limit of US is:
a. 19,000kHz
b. 10,000MHz
c. 20,000 msec
d. 15,000Hz

Question 4

Which is not an acoustic variable?
a. density
b. pressure
c. distance
d. intensity

Question 5

The effects of soft tissue on US are called:
a. acoustic proliferation
properties
b. dynamic effects
c. acoustic propagation properties
d. biologic effects

Question 6

Al of the following are true EXCEPT:
a. Two waves with identical frequencies must interfere constructively.
b. Constructive interference is associated with waves that are in-phase.
c. Out-of-phase waves interfere destructively
d. Waves of different frequencies may exhibit both constructive and destructive interference at different times.

Question 7

Put in decreasing order:
a. deca
b. deci
c. micro
d. centi

Question 8

—–is the time to complete one cycle.
a. pulse duration
b. pulse period
c. period
d. duration period

Question 9

Which of the
following sound waves is ultrasonic and least useful in diagnostic imaging?
a. 30 KHz
b. 8 MHZ
c. 8,000 Hz
d. 3,000 kHz
e. 15 Hz

Question 10

What is the frequency of a wave with 1 msec period?
a. 10,000 Hz
b.1000 KHz
c. 1 KHz
d. 1 MKz

Question 11

is the distance covered by one cycle.
a. pulse length
b. wavelength
c. cycle distance
d. cycle duration

Question 12

Which of th
e following is determined by the source and the medium?
a. frequency
b. period
c. propagation speed
d. range resolution

Question 13

Propagation speed = wavelength
a. pulse duration
b. period
e. number of cycles in the puls e
d. frequency

Question 14

As a result of the
propagation speed increases.
a. increasing stiffness and increasing density
b. increasing stiffness and increasing elasticity
c. decreasing compressibility and decreasing den
sity
d. decreasing stiffness and decreasing density

Question 15

Put in decreasing order of propagation speed.
a. gas
b. liquid
c. solid

Question 16

I the frequency of US is increased from 0.77MHz to 1.54MHz, what happens to the wavelength?
a. doubles b. halved
c. remains the same
d. 4 times greater

Question 17

Asound waves’ frequency is 001 10 MHz. The wave is traveling
in soft tissue. What is its wavelength?
a. 0.15 mm
b. 1.54mm
c. 15.4mm
d. 0.77 mm e. 10 MHz

Question 18

If the frequency of an US wave
is doubled, what happens to the period?
a. doubles
b. halved-
c. remains the same
d. 4 times greater

Question 19

If the frequency of US is increased from 0.77MHz to 1.54MHz, what happens to the propagation speed?
a. doubles
b. halved
c. remains the s a m e
d. 4times

Question 20

The units of pulse repetition frequency are
a. per minute
b. msec
c. mm/us
d. MHx

Question 21

The time from the beginning of a puise until its end is
a. period
b. pulse duration
c. puise length
d. PRF

Question 22

What happens ot hte speed of sound in a medium when the
bulk modulus of the medium increases?
a. faster
b. slower
c. u n c h a n g e d

Question 23

resolution is determined by the spatial pulse length.
v a . r a d i a l
b. image
c. axial
d. a n g u l a r

Question 24

If a wave’s amplitude is doubled, what happens to the power?
a. nothing
b. halved
c. doubled
d. quadrupled

Question 25

fI the level of an acoustic variable ranges from 55 to 105, what is the amplitude?
a. 105
b. 50
c. 25
d. 55

Question 26

Power of sound has units of
a. dB
b. dB/cm
c. watts
d. watts/cm

Question 27

If the intensity of a sound beam remains unchanged while the beam area is reduced in half, what has happened to the power?
a. quadrupled
b. doubled
c. halved
d. unchanged

Question 28

Which of these intensities is smallest?
a. SATP
b. SPTP
C. SATA

Question 29

The duty factor for continuous wave ultrasound is
а. 10.0
b. 1%
c. 1.0
d. 0 . 0 %

Question 30

What is the minimum value of the duty factor?
a. 10.0
b. 1%
c. 1.0
d. 0.0%

Question 31

What are the units of intensity?
a. watts
b. decibels
c. watts/cm squared
d. d e c i b e l s

Question 32

What h
appens to the speed of sound ni a medium when the bulk modulus of the medium decreases?
a. faster
b. Slower
c . u n c h a n g e d

Question 33

The units of attenuation
a r e ——- this is a ——–scale.
a. mm/cm, parametric
b. dB/m, multiplicative
c. none, relative
cd. dB, logarithmic

Question 34

Sound intensity is decreased by 75%. How many decibels of attenuation is this?
‘a. 6dB
b. 9dB
c. 5dB
d. 10dB

Question 35

The fundamental frequency of a transducer is 2.5MHz. What
is the second harmonic frequency?
a. 1.25MHz
b. 4.5MHz
c. 5MHz
d. 5cm

Question 36

A pulses emitted by a transducer and is traveling in soft tissue. The go-return time, or time-of-flight, of a sound pulse is 130
microseconds.
What is the reflector depth?
a. 10 cm
b. 10 mm
.c 10 m
d. 130 mm e. 13 cm

Question 37

If a 5MHz sound wave is traveling ni the tissues listed below, which wil have the longest wavelength?
a. Fat
b. Air
c. Muscle
d. Bone

Question 38

If a 5MHz sound wave is traveling in the tissues listed below, which wil
l have the shortest wavelength?
a. Fat I
b. A i r
c. Muscle
d. Bone

Question 39

What is the
approximate attenuation coefficient of 1MHz US in soft tissue? “
a. 0.5dB/cm
b . 1 c m
c. 3dB/cm
d. 1dB

Question 40

The rayl is the unit of:
a. intensity
b. reflectance
c. density
d . impedance

Question 41

Impedance is the —-of —— and—–
a. product, propagation speed, density
b. sum, stiffness, density
c. quotient, stiffness, propagation speed
d. difference, attenuation, density

Question 42

What are attenuation’s three components?

Question 43

For soft tissue, the
approximate attenuation coefficient in dB/cm is equal to one-half
in
a. wavelength, mm
b. frequency, Hz
c. frequency, MHz
d. impedance, rayls

Question 44

As the impedances of two
media become vastly different, t h e
a . reflection increases
b. transmission increases
c. refraction increases
d. absorption increases

Question 45

The angle between an US pulse and the boundary between two media is 90°. What is this called?
a. direct incidence
b. oblique incidence
c. indirect incidence
d. orthogonal incidence

Question 46

The angle between an US pulse and the boundary between two media is 56°. This is called:
a. direct incidence
b. oblique incidence
c. indirect incidence
d. orthogonal incidence

Question 47

Refraction only occurs if there

a. normal incidence & different impedances
b. indirect intensity &different propagation speeds
c. oblique incidence & different propagation speeds
d. oblique frequency & identical impedances

Question 48

With normal incidence, what factors affect refraction of US?
a. propagation speeds
b. frequencies
c. attenuation coefficients
d. none of the above

Question 49

(True or False) With right angle incidence, reflections are always generated at a boundary if the propagation speeds of the media are different.

Question 50

——–is a redirection of US in many directions as a result of a rough boundary between two media.
a. refraction
b. Rayleigh scattering
c . scattering
d. reflection

Question 51

Which of the following tissues is most likely to create Rayleigh scattering?
a. red blood cells
b. muscle
c fat
d. bone

Question 52

(True or False) With normal incidence the angle is 180°.

Question 53

Under which of the follow
ing conditions is axial resolution improved?
a. decreased spatial pulse length
b. decreasedpulseamplitude
c. decreased imaging depth
d. decreased pixel size
e. decreased beam diameter