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Flashcards in SPI review Deck (48):
1

typical values for period

0.06-0.5 micro sec

2

typical values of frequency

2-15 MHz

3

Amplitude can have units of:

pascals, grams/cm^3, cm, dB

4

typical values for intensity

.001-100 watts/cm^2

5

typical value for wavelength

0.1-0.8mm

6

typical values for propagation speed

1500-1600 m/s

7

equation for wavelength

wavelength (mm)= 1.54 (mm/micro sec)/ frequency (MHz)

8

typical values for pulse duration

.5-3 micro sec

2-4 cycles

9

pulse duration=

cycles in pulse x period

10

typical values for PRP

100 micro sec to 1 msec

11

typical values of PRF

1000 to 10000 Hz

12

typical value of duty factor

0.1 % to 1 %

.001 to .01

13

Duty factor =

pulse duration/ PRP

14

What typ of imaging has high PRF, high duty factor, and short PRP?

shallow

15

typical values of spatial pulse length

0.1 to 1 mm

16

spatial pulse length=

number of cycles x wavelength

17

what type of imaging has low PRF, low duty factor, and long PRP?

deep

18

intensity most relevent to tissue heating?

SPTA

19

decibles have what type of scale?

relative

20

units for attenuation coefficient

dB/cm

21

attenuation coefficient in soft tissue

.5 dB/cm/MHz

22

impedance is ______ not _________.

calculated, not measured

23

typical values for impedance

1,250,000 and 1,750,000 rayls

24

refraction requires?

oblique incidence and different speeds

25

snells law

sine (transmission angle)=prop speed 2

_______________________________

sine (incident angle)=prop speed 1

26

A property of certain materials to create a voltage when pressure is applied?

piezoelectric effect

27

Q factor =

resonant freq/bandwidth

28

axial resolution equation in soft tissue

.77 x # cycles in pulse/ freq

29

A-mode

xaxis: depth

yaxis: amplitude

30

B-mode

xaxis: depth

zaxis: brightness

31

m-mode

xaxis: time

yaxis: depth

32

sector
mechanical steering

fixed focusing

1 crystal

image loss

mechanical

33

rectangular

no steering

fixed focusing

200 rectangular crystals

vert line dropout

linear switched

34

sector

electronic steering

fixed focusing

200 rectangular crystals

poor steering and focusing

linear phased array

35

sector

mechanical steering

electronic focusing

5 ring crystals

horiz line dropout

annular phased

36

blunted sector

no steering

fixed focusing

200 rectangular crystals

vert line dropout

convex sequential

37

blunted sector

electronic steering

electronic focusing

200 rectangular crystals

poor steering and focusing

convex phased

38

flat top sector

electonic steering

electronic focusing

200 rectangular crystals

poor steering and focusing

vector

39

frame rate is determined by what two factors?

speed of sound in a medium and depth of view

40

what is a beam former?

creates the firing patterns for phased array systems

41

The science of identifying and measuring those characteristics of an US field which are especially relevent to its potential for producing biological effects?

Dosimetry

42

Mechanistic approach is cause and effect, what is the emperical approach?

exposure and response

43

_______ beams are less likely to cause temp elevation in tissues.

focused

44

intesity limits for unfocused sound and focused sound?

unfocused: 100 mW/cm^2

focused: 1000 mW/cm^2

45

microbubbles get _______ during rarefractions.  cavitation is more likely to occur in ______ than other tissues.

bigger

lung

46

Mechanical index is higher, more likely to produce cavitation with:

peak rarefraction pressure and lower frequency

47

bulk modulus also means what?

stiffness

48