Chapter 1 Flashcards
What is acoustic pressure?
Quantification of strength of a wave
What is acoustic pressure measured in?
Pascals
Do longer or shorter pulses tend to have bigger frequency spectrums?
Shorter pulses
What is period?
The inverse of frequency
What determines the speed of sound in a medium?
The materials density and compressibility (stiffness)
- sound travels slower in a more dense and more compressible material
What is acoustic impedance?
The property of a tissue that influences the strength/amplitude of reflected echoes
What is the symbol for acoustic impedance?
Z
What is the equation for acoustic impedance?
Z = pc
p = mediums density
c = speed of sound
What are diffuse reflectors?
Rough edges that produce reflection of echoes in different directions - not perpendicular
How do specular and scattered reflections differ?
Scattered echoes are weaker
What are Rayleigh scatterers?
Scattering object, whose dimensions are «_space;ultrasound wavelength (e.g. RBC)
What are the two sources of attenuation?
- Reflection and scatter at interfaces
- Tissue absorption
How does attenuation change with frequency?
Higher frequencies are attenuated more than low frequencies
