Chapter 3 - p.67

Question 1

What are the 3 mechanical wave interactions with the medium which constitute attenuation ?

Answer 1

absorption
reflection
refraction

Question 2

Absorption is the conversion of energy from an acoustic wave to _____________

Answer 2

heat

Question 3

Absorption (increases/decreases) with increasing frequency

Answer 3

increases

Question 4

Of the three interactions which constitute attenuation, which is the dominant factor in soft tissue ?

Answer 4

absorption

Question 5

What laws tells at what angle an incident beam will be transmitted ?

Answer 5

Snell’s law

Question 6

Normal incidence implies that the incident beam direction is __________ to the media interface.

a. parallel
b. perpendicular
c. obtuse
d. oblique

Answer 6

perpendicular

Question 7

Normal incidence is really just a special case governed by ___________ law. For normal incidence , angle of incidence = ____________ . Since sin angle of incidence = sin (0)t = 0 , implying 0t = 0 and there is no ___________

Answer 7

shell’s

no refraction

Question 8

Acoustic impedance is given by the equation Z=

Answer 8

p x c

Question 9

The unit for acoustic impedance is the ___________

Answer 9

Rayl

Question 10

The percentage of a normal incident beam reflected and transmitted at the interface of 2 media is given by __________

Answer 10

check book p.548

Question 11

For specular reflection, the incident angle is equal to

a. the normal angle
b. the refraction angle
c. the reflected angle
d. transmitted angle

Answer 11

c

Question 12

If the wavelength is small with respect to the structure size and the surface is smooth ________ reflection should occur.

Answer 12

specular

Question 13

If the surface is rough and the wavelength is larger with respect to the structure size ________ reflection should occur

Answer 13

scattering

Question 14

For ________ tissue the attenuation rate is approximately 0.5 dB/cm-MHz

Answer 14

soft

Question 15

For muscle, the attenuation rate is approx _____________

Answer 15

1 db/cm-MHz

Question 16

At a depth of 5cm, in muscle, what would the attenuation be for a 7.5 MHz beam?

Answer 16

37.5 dB