DMSO 1302: Ultrasound Physics: EXAM 2
Questions And Answers Latest Update
Attenuation (a) -
correct answer ✅-is the weakening of sound while it propagates
- limits the imaging depth (high frequencies are attenuated faster
therefor are shallower than lower frequencies)
-its weakening effect must be compensated by the transducer
- a = 1/2(f x l) Units = decibels (dB)
-3 mechanisms of attenuation: absorption, reflection and scattering
-DIRECTLY RELATED TO DISTANCE
-DIRECTLY RELATED TO FREQUENCY
Attenuation Coefficient -
correct answer ✅- the number of decibels of attenuation that
occurs when sound travels one centimeter
- Unit: dB/cm
,DMSO 1302: Ultrasound Physics: EXAM 2
Questions And Answers Latest Update
- 0.5 dB of attenuation per centimeter for each megahertz of
frequency (in soft tissues)
- the farther the sound travels, the more attenuation
- equal to 1/2 of the operating frequency
- f/2
Absorption -
correct answer ✅- conversion of sound energy to heat
- greatest contributor to attenuation in tissues
- Potential source of bio-effects (discussed later)
Amplitude -
correct answer ✅-For a wave or vibration, the maximum
displacement on either side of the equilibrium (baseline) position.
, DMSO 1302: Ultrasound Physics: EXAM 2
Questions And Answers Latest Update
- positive amplitudes (above baseline) and negative amplitudes
(below baseline)
-units that are appropriate to the acoustic variable considered
EX: pressure amplitude = pascals (Pa)
Intensity ( I ) -
correct answer ✅- is the ability to accomplish work
EX: heat, light, x-rays, microwaves, sound
- also the rate at which energy passes through a unit area
- I = Power(mW) divided by Area(cm^2)
- Units: mW/cm^2 and W/cm^2 (Watts)
- intensity is proportional to amplitude^2
EX: if amplitude is doubled then intensity is quadrupled
if amplitude is halved then intensity is quartered
Questions And Answers Latest Update
Attenuation (a) -
correct answer ✅-is the weakening of sound while it propagates
- limits the imaging depth (high frequencies are attenuated faster
therefor are shallower than lower frequencies)
-its weakening effect must be compensated by the transducer
- a = 1/2(f x l) Units = decibels (dB)
-3 mechanisms of attenuation: absorption, reflection and scattering
-DIRECTLY RELATED TO DISTANCE
-DIRECTLY RELATED TO FREQUENCY
Attenuation Coefficient -
correct answer ✅- the number of decibels of attenuation that
occurs when sound travels one centimeter
- Unit: dB/cm
,DMSO 1302: Ultrasound Physics: EXAM 2
Questions And Answers Latest Update
- 0.5 dB of attenuation per centimeter for each megahertz of
frequency (in soft tissues)
- the farther the sound travels, the more attenuation
- equal to 1/2 of the operating frequency
- f/2
Absorption -
correct answer ✅- conversion of sound energy to heat
- greatest contributor to attenuation in tissues
- Potential source of bio-effects (discussed later)
Amplitude -
correct answer ✅-For a wave or vibration, the maximum
displacement on either side of the equilibrium (baseline) position.
, DMSO 1302: Ultrasound Physics: EXAM 2
Questions And Answers Latest Update
- positive amplitudes (above baseline) and negative amplitudes
(below baseline)
-units that are appropriate to the acoustic variable considered
EX: pressure amplitude = pascals (Pa)
Intensity ( I ) -
correct answer ✅- is the ability to accomplish work
EX: heat, light, x-rays, microwaves, sound
- also the rate at which energy passes through a unit area
- I = Power(mW) divided by Area(cm^2)
- Units: mW/cm^2 and W/cm^2 (Watts)
- intensity is proportional to amplitude^2
EX: if amplitude is doubled then intensity is quadrupled
if amplitude is halved then intensity is quartered
