Physics chapter 6

book and quiz questions

Name 3 components of attenuation

Absorption, scattering, reflection

As the path length increases, the attenuation of ultrasound in soft tissues _____.

increases

Attenuation in lung tissue is (greater, less, the same) attenuation in soft tissue.

greater than

Attenuation in bone is ____ attenuation in soft tissue.

greater than

Attenuation in air is ___ attenuation in soft tissue?

What are the units of attenuation?

Decibles (dB)

T or F. In a given medium, attenuation unrelated to the speed of sound?

True

What is the relationship between ultrasound frequency and the attenuation coefficient in soft tissue?

in soft tissue, the attenuation coefficient in dB per cm is one half of frequency.

atten. coef. = frequency / 2

What are the units of the half value layer thickness?

distance: cm

As path length increase the boundary layer ___

remains the same

As path length increases, the attenuation coefficient of ultrasound in soft tissue ____.

remain the same

impedance is associated with

only the medium

acoustic impedance = __ x __

density x speed

Two media A and B have the same densities. The speed of sound in A is 10% higher than B. Which medium has a higher acoustic impedance.

Medium A

Impedance is important in ____ at boundaries.

reflections

Which is better to use while examining a carotid artery, a 7.5 or 3.0 MHz transducer?

7.5 Mhz

A sound wave with an intensity of 50 W/cm² strikes a boundary and is totally reflected. What is the intensity reflection coefficient

100%

A sound wave with an intensity of 50 W/cm² strikes a boundary and is totally reflected. What is the reflected intensity?

50 W/cm²