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Flashcards in SPI review 2 Deck (103)
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1

attenuation coefficient and its units

the amount of attenuation per cm units dB/cm

2

attenuation cefficient is directly related to

frequency

3

attenuation coeff does not change when ________ changes

path length

4

in soft tissue attenuation coeff is approcimatley

1/2 the freqyency

5

mathmatical expression for attenuation coeff in soft tissue

0.5dB/cm/MHz

6

impedance

a number associated with a meduims resistance

calculated not measured

units are Rayls "Z"

7

acoustic impedance =

density x propagation speed

8

rayleigh scattering is =

freq to the 4th

9

oblique incidence

anything other than right angels

10

AKA normal incidence

perpendicular
orthogonal
right angel
ninety degrees

11

typical % of reflected intensity between soft tissue boundary

1%

12

% refelcted at air/tissue interface

99%

13

% reflected at bone/tissue interface

50%

14

refraction is

transmission with a bend

15

the physics of refraction is described by

snells law

16

refraction requirs _____ incidence

oblique (and diff speeds)

17

the angel of reflections is = to

the angle of incidence

18

which of the following best descrobes a refelction from a rough boundry?
non diffuse, absolute, rayleigh, smooth, non specular

non specular

19

the time of flight and and distance are ________ related

directly

20

range equation

distance to boundry = go return time x speed / 2

21

in soft tissue, every ____ of go return time means the reflector is ___ deeper in the body

13 micro sec
1cm

22

a property of certain material to create a voltage when pressure is applied or when the material is mechanically deformed

piezoelectric effect

23

materials deform or change shape when a voltage is applied to them

reverse piezoelectric effect

24

PZT AKA

ferroeclectric material

25

natural PZT

quartz, rochelle salts, tourmaline

26

man made PZT

barium titanate, lead metaniobate, lead titanate, lead zirconate titanate

27

temp PZT will depolarize at

360C* or 680F*

28

the complete destruction of all living microorganisms by heat, chemical agents, or radiation

sterilization

29

reduce infectious organisms

disinfection

30

thickness of PZT

1/2 wavelength thick