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2024 DAVIES SPI II PHYSICAL PRINCIPLES OF ARDMS EXAM WITH CORRECT ANSWERS
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2024 DAVIES SPI II PHYSICAL PRINCIPLES OF ARDMS EXAM WITH CORRECT ANSWERS
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2024 DAVIES SPI II PHYSICALPRINCIPLES OF ARDMS EXAM
WITH CORRECT ANSWERS
Attenuation of the sound beam increases with increasing:
A. Path length
B. Absorption
C. Frequency
D. Scattering and reflection
E. All of the above - CORRECT-ANSWERSE. All of the above
<The attenuation coefficient is the degree of attenuation for each centimeter
of sound propagation. Anything that increases attenuation will increase the
attenuation coefficient>
Which prefix equals 10^(-3)?
A. Micro
B. Milli
C. Mega
D. Centi
E. None of the above - CORRECT-ANSWERSB. Milli
<Micro is 10^(-6), mega is 10^6, and centi is 10^(-2)>
You have increased the transmit power while performing a pelvic ultrasound
examination. This action increases which of the following?
A. Penetration
B. Acoustic power
C. Image brightness
D. Voltage applied to the transducer elements
E. All of the above - CORRECT-ANSWERSE. All of the above
Which of the following factors does NOT affect impedance?
A. Stiffness
B. Density
C. Propagation speed
,D. Frequency
E. All of the above affect impedance - CORRECT-ANSWERSD. Frequency
<Impedance increases if density is increased, or propagation speed is
increased. Impedance is also affected by stiffness. It is not affected by
frequency. Z=rc, where r is the density and c is the speed of sound. C
depends on density and tissue stiffness>
What determines acoustic impedance?
A. Frequency and propagation speed
B. Frequency and interface size
C. Density and propagation speed of the medium
D. Angle of incidence and media propagation speed
E. Frequency and media density - CORRECT-ANSWERSC. Density and
propagation speed
<Acoustic impedance is determined by the density and propagation speed of
the medium as expressed in the equation z=rc, where z represents acoustic
impedance, r represents density, and c represents propagation speed>
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 - CORRECT-ANSWERSC. The pulse duration
is increased
<Pulse duration is the time it takes to complete one pulse. If the number of
cycles in the pulse is increased, it will take more time for one pulse to occur.
Frequency is how many cycles occur in one second--not how many cycles are
contained in one pulse
Propagation speed is not affected by the number of cycles in a pulse; it is
determined by the medium
Period is the inverse of frequency. It describes the time it takes for one cycle
to occur--not the time it takes for one pulse to occur. When frequency
increases, period decreases, and vice versa
Bulk modulus is related to media stiffness and helps to determine
propagation speed>
Which sound beam frequency would exhibit the greatest intensity loss with
increasing depth?
,A. 10 MHz
B. 8 MHz
C. 5 MHz
D. 3 MHz
E. 2 MHz - CORRECT-ANSWERSA. 10 MHz
Which of the following is most likely also to decrease beam intensity?
A. Increasing acoustic output
B. Decreasing receiver gain
C. Increasing focusing
D. Increasing beam area
E. Increasing amplitude - CORRECT-ANSWERSD. Increasing beam area
<For a given output power (mW) the intensity (mW/cm^2) is expected to fall
if the beam area (cm^2) is increased>
While imaging a cyst, you notice shadowing posterior to each lateral border
of the cyst. What is the source of the shadows?
A. Redirection of the sound beam at an interface with different propagation
speeds and a curved surface
B. Bending of the sound beam due to different media propagation speeds
C. Increased attenuation of the sound beam at the borders of the cyst
D. Lateral misregistration of the cyst due to a multipath artifact
E. Diffraction of the sound beam resulting in a weakened signal at the lateral
borders of the cyst - CORRECT-ANSWERSB. Bending of the sound beam due
to different media propagation speeds
<This is refraction of the sound beam and occurs whenever there is both
oblique incidence and a difference in media propagation speeds>
What system control should you adjust to compensate for sound attenuation
with increasing depth?
A. Dynamic range
B. TGC
C. Transmit power
D. Overall Receiver gain
E. Focus position - CORRECT-ANSWERSB. TGC
<TGC and DGC (depth gain compensation) are two names for the same
system control. TGC is a method of increasing amplification applied to echo
signals arising from deeper structures to account for the weakening
(attenuation) of the sound beam with depth. If the TGC is adjusted
, appropriately, like structures will appear with the same brightness even if
they are located at different depths.
The overall receiver gain (master gain) amplifies signals from all depths
equally and does not compensate for attenuation changes at specific
depths>
According to Snell's law the angle of transmission is related to the incident
beam angle and:
A. The amount of acoustic impedance mismatch at an interface
B. The change in frequency that occurs at an interface
C. One-half of the angle of incidence
D. The relative speeds of sound in the two media
E. The percentage of diffraction distal to the interface - CORRECT-
ANSWERSD. The relative speeds of sound in the two media
<Snell's law dictates the angle of transmission that will occur at an interface
with refraction of the sound beam. Refraction (bending) of the sound beam
occurs whenever there is oblique incidence and different propagation speeds
between two media>
An echo from which one of the following sound reflectors is most dependent
on the angle of incidence?
A. Rayleigh scatterer
B. Diffuse reflector
C. Specular reflector
D. Acoustic scatterer
E. Nonspecular reflector - CORRECT-ANSWERSC. Specular reflector
<With specular reflection, the angle of reflection is equal to the angle of
incidence. So, in order to get most of the reflected sound to be angled back
at the transducer, the transducer must be oriented so that the sound will
strike the interface perpendicularly. That is why we get the best images of
the kidney, aorta, and similar structures when we have them positioned
horizontally on the ultrasound image>
What determines the speed of sound?
A. Frequency of sound wave
B. Intensity of sound wave
C. Attenuation of sound wave
D. Reflection of sound wave
E. Medium through which sound wave passes - CORRECT-ANSWERSE.
Medium through which sound wave passes
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