DMS 216 CHAPTER 6 AND 7 EXAM
QUESTIONS AND ANSWERS
What is attenuation in the context of sound waves? - Answer- The decrease in intensity,
power, and amplitude of a sound wave as it travels.
How is sound converted when received by a transducer? - Answer- It is converted into
an electrical signal that is then amplified.
What is the purpose of decibel notation? - Answer- To report the degree of attenuation
or amplification of sound.
What does a logarithm represent in decibel calculations? - Answer- The number of 10s
multiplied to create the original number.
What is the decibel level when a wave's intensity doubles? - Answer- +3 dB
What does -10 dB indicate about a wave's intensity? - Answer- The intensity has
decreased by a factor of 10.
What are the three processes that contribute to attenuation? - Answer- Reflection,
scattering, and absorption.
What occurs during reflection of sound waves? - Answer- A portion of the wave's energy
is redirected back to the source.
What type of reflection occurs from a very smooth reflector? - Answer- Specular
reflection.
What is diffuse reflection? - Answer- Disorganized sound returning towards the
transducer from irregular boundaries.
What is scattering in the context of ultrasound? - Answer- The random redirection of
sound in many directions, often due to small tissue interfaces.
What is Rayleigh scattering? - Answer- Occurs when the structure's dimensions are
much smaller than the beam's wavelength, redirecting sound equally in all directions.
, How does frequency affect scattering? - Answer- Higher frequency sound beams
scatter more than lower frequency sound beams.
What is absorption in ultrasound? - Answer- The conversion of ultrasound energy into
another form, such as heat.
What is the attenuation coefficient? - Answer- The number of decibels of attenuation
that occurs when sound travels one centimeter.
What factors determine total attenuation? - Answer- Frequency of the sound, distance
the beam travels, and tissue type.
What is the typical range for half-value layer thickness? - Answer- 0.25 to 1.0 cm.
What does high frequency result in regarding half-value layer thickness? - Answer- A
thin half-value layer due to higher attenuation.
What is acoustic impedance? - Answer- The acoustic resistance to sound traveling
through a medium, calculated by multiplying density by the speed of sound.
What is the relationship between frequency and attenuation in soft tissue? - Answer-
Attenuation coefficient is directly related to frequency; it equals half the frequency in
MHz.
What is the significance of decibels in ultrasound imaging? - Answer- Decibels measure
the strength and changes in ultrasound signals.
What is the purpose of the range equation in ultrasound? - Answer- To determine the
depth of a reflector by measuring the time a sound pulse takes to travel to the reflector
and back.
What does 'time-of-flight' refer to in ultrasound? - Answer- The elapsed time from pulse
creation to pulse reception.
How does time-of-flight relate to reflector depth? - Answer- Time-of-flight is longer for
deeper depths and shorter for shallow depths.
What is the average speed of sound in soft tissue? - Answer- 1540 m/s or 1.54 mm/μs.
How can the depth of a reflector be calculated? - Answer- Depth (mm) = 1.54 mm/μs x
time of flight (μs) / 2.
What is the 13 microsecond rule in ultrasound? - Answer- For every 13 μs of go-return
time, the object creating the reflection is 1 cm deeper in the body.
QUESTIONS AND ANSWERS
What is attenuation in the context of sound waves? - Answer- The decrease in intensity,
power, and amplitude of a sound wave as it travels.
How is sound converted when received by a transducer? - Answer- It is converted into
an electrical signal that is then amplified.
What is the purpose of decibel notation? - Answer- To report the degree of attenuation
or amplification of sound.
What does a logarithm represent in decibel calculations? - Answer- The number of 10s
multiplied to create the original number.
What is the decibel level when a wave's intensity doubles? - Answer- +3 dB
What does -10 dB indicate about a wave's intensity? - Answer- The intensity has
decreased by a factor of 10.
What are the three processes that contribute to attenuation? - Answer- Reflection,
scattering, and absorption.
What occurs during reflection of sound waves? - Answer- A portion of the wave's energy
is redirected back to the source.
What type of reflection occurs from a very smooth reflector? - Answer- Specular
reflection.
What is diffuse reflection? - Answer- Disorganized sound returning towards the
transducer from irregular boundaries.
What is scattering in the context of ultrasound? - Answer- The random redirection of
sound in many directions, often due to small tissue interfaces.
What is Rayleigh scattering? - Answer- Occurs when the structure's dimensions are
much smaller than the beam's wavelength, redirecting sound equally in all directions.
, How does frequency affect scattering? - Answer- Higher frequency sound beams
scatter more than lower frequency sound beams.
What is absorption in ultrasound? - Answer- The conversion of ultrasound energy into
another form, such as heat.
What is the attenuation coefficient? - Answer- The number of decibels of attenuation
that occurs when sound travels one centimeter.
What factors determine total attenuation? - Answer- Frequency of the sound, distance
the beam travels, and tissue type.
What is the typical range for half-value layer thickness? - Answer- 0.25 to 1.0 cm.
What does high frequency result in regarding half-value layer thickness? - Answer- A
thin half-value layer due to higher attenuation.
What is acoustic impedance? - Answer- The acoustic resistance to sound traveling
through a medium, calculated by multiplying density by the speed of sound.
What is the relationship between frequency and attenuation in soft tissue? - Answer-
Attenuation coefficient is directly related to frequency; it equals half the frequency in
MHz.
What is the significance of decibels in ultrasound imaging? - Answer- Decibels measure
the strength and changes in ultrasound signals.
What is the purpose of the range equation in ultrasound? - Answer- To determine the
depth of a reflector by measuring the time a sound pulse takes to travel to the reflector
and back.
What does 'time-of-flight' refer to in ultrasound? - Answer- The elapsed time from pulse
creation to pulse reception.
How does time-of-flight relate to reflector depth? - Answer- Time-of-flight is longer for
deeper depths and shorter for shallow depths.
What is the average speed of sound in soft tissue? - Answer- 1540 m/s or 1.54 mm/μs.
How can the depth of a reflector be calculated? - Answer- Depth (mm) = 1.54 mm/μs x
time of flight (μs) / 2.
What is the 13 microsecond rule in ultrasound? - Answer- For every 13 μs of go-return
time, the object creating the reflection is 1 cm deeper in the body.
