Physics of Breast Ultrasound/Misc.
Questions with Correct Answers
What are 6 advantages of ultrasound - ANSWER✔✔-no ionizing radiation, real time,
portable, excellent resolution of superficial structures, Doppler for blood flow, cost
(ability to do multiple sequential exams)
What is the definition of sound? - ANSWER✔✔-a result of mechanical energy
producing alternation of compression and rarefaction of the conducting medium as it
travels in the form of a wave
What 2 things do not affect velocity of propagation? - ANSWER✔✔-frequency and
wavelength
Sound pulses in the body are (4): - ANSWER✔✔-reflected, scattered, refracted,
absorbed
When does reflection or backscatter occur? - ANSWER✔✔-When the pulse encounters
an interface between tissues with different acoustic impedances
, What is impedance? What is the relationship of impedance to reflection (backscatter)? -
ANSWER✔✔-product of speed of sound and tissue density; strength depends on how
big difference is of tissues (size, surface characteristics, orientation); greater acoustic
impedance = greater backscatter/reflection
What is a specular reflector? How does angle affect this? - ANSWER✔✔-a larger
interface that is smooth produces strong reflections; if perpendicular to direction of
pulse = strong reflection and strong signal; if not perp. = strong reflection but weak
pulse (not sent to crystals)
What is scattering? When does it occur (2)? - ANSWER✔✔-a redirection of sound in
multiple directions; produces a weak signal either because the acoustic interface is
smaller than the wavelength or by striking a large interface that is rough
What is refraction? What can it cause? - ANSWER✔✔-a change in direction of sound
when sound encounters an interface between 2 tissues that transmit at different speeds
(can cause mislocalization of a structure)
What is absorption? What is it a major cause of? What tissues absorb more? -
ANSWER✔✔-loss of sound energy secondary to its conversion to thermal energy; major
cause of acoustic shadowing; greater in soft tissue than fluid; greater in bone than in
soft tissue
Questions with Correct Answers
What are 6 advantages of ultrasound - ANSWER✔✔-no ionizing radiation, real time,
portable, excellent resolution of superficial structures, Doppler for blood flow, cost
(ability to do multiple sequential exams)
What is the definition of sound? - ANSWER✔✔-a result of mechanical energy
producing alternation of compression and rarefaction of the conducting medium as it
travels in the form of a wave
What 2 things do not affect velocity of propagation? - ANSWER✔✔-frequency and
wavelength
Sound pulses in the body are (4): - ANSWER✔✔-reflected, scattered, refracted,
absorbed
When does reflection or backscatter occur? - ANSWER✔✔-When the pulse encounters
an interface between tissues with different acoustic impedances
, What is impedance? What is the relationship of impedance to reflection (backscatter)? -
ANSWER✔✔-product of speed of sound and tissue density; strength depends on how
big difference is of tissues (size, surface characteristics, orientation); greater acoustic
impedance = greater backscatter/reflection
What is a specular reflector? How does angle affect this? - ANSWER✔✔-a larger
interface that is smooth produces strong reflections; if perpendicular to direction of
pulse = strong reflection and strong signal; if not perp. = strong reflection but weak
pulse (not sent to crystals)
What is scattering? When does it occur (2)? - ANSWER✔✔-a redirection of sound in
multiple directions; produces a weak signal either because the acoustic interface is
smaller than the wavelength or by striking a large interface that is rough
What is refraction? What can it cause? - ANSWER✔✔-a change in direction of sound
when sound encounters an interface between 2 tissues that transmit at different speeds
(can cause mislocalization of a structure)
What is absorption? What is it a major cause of? What tissues absorb more? -
ANSWER✔✔-loss of sound energy secondary to its conversion to thermal energy; major
cause of acoustic shadowing; greater in soft tissue than fluid; greater in bone than in
soft tissue
