Acoustic Impedance Quiz

What is the formula for acoustic impedance (Z) of a tissue?

• Z = ρ (kg/m3) - v (m/s2)

• Z = ρ (kg/m3) + v (m/s2)

• Z = ρ (kg/m3) × v (m/s2)

• Z = ρ (kg/m3) ÷ v (m/s2)

What is the unit of measurement for acoustic impedance?

• kg/m3s

• kgm-2s-1

• kgm-3s-1

• kg/m2s

What is the Reflection coefficient (R) formula for an ultrasound wave incident perpendicularly upon an interface?

• R = (Z1+Z2 / Z1-Z2)2

• R = (Z1-Z2 / Z1+Z2)2

• R = (Z1+Z2 / Z1+Z2)2

• R = (Z1-Z2 / Z1-Z2)2

What does the Transmission coefficient (T) describe?

• The speed of sound in a medium

• The fraction of the incident energy that is transmitted

• The fraction of the incident energy that is reflected

• The intensity of the reflected wave

What is the formula for Reflection loss (dB) related to tissue impedance values?

• Reflection loss (dB) = 30log (Z2 - Z1) / (Z2 + Z1)

• Reflection loss (dB) = 20log (Z2 - Z1) / (Z2 + Z1)

• Reflection loss (dB) = 40log (Z2 - Z1) / (Z2 + Z1)

• Reflection loss (dB) = 10log (Z2 - Z1) / (Z2 + Z1)

What is the main factor that determines the brightness of a structure in an ultrasound image?

• The strength of the reflection or echo

• The density of the medium

• The speed of sound in the medium

• The amplitude of the reflected pulse

What is the term used for a large difference in acoustic impedances of materials on each side of a boundary?

• Acoustic impedance difference

• Acoustic impedance match

• Acoustic impedance contrast

• Acoustic impedance mismatch

What is used during ultrasound examinations to remove air pockets between the ultrasound transducer and the patient's skin?

• Acoustic coupling device

• Water paths

• Various creams and gels

• Air pockets removal tool

What is the fraction of the incident energy that is transmitted across an interface?

• R

• T

• I

• Z