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Flashcards in SPI Review Deck (100):
1

reciprical of .001

1000

2

reciprical of 1/10

10

3

how much bigger is one billion than one thousand

1,000,000

4

what happens to the period of a wave as it proagates

it remains the same

5

as sound travels through a medium what term descrives the effects of the meduim on the sound wave

acoustic propagation properties

6

what is the unit for the speed of ultrasound in soft tissue

m/s (1.54)

7

what is the freq of a wave with 1msec period

1khz

8

what is the distance covered by one cycle

wavelength

9

which of the following is determinded by the source and the medium? freq, period, prop speed, or range resolution

range resolution

10

a sound waves freq is 10MHz. The wave is traveling in soft tissue. What is the wavelength?

0.15 mm

11

what happens to the speed of sound in a medium when the bulk modulus of the medium increase

faster

12

if the level of an acoustic variable ranges from 55 to 105, what is the amplitude

25

13

if the intensity of a sound beam remains unchanged while the beam area is reduced in half. what has happened to the power

halved

14

what is the minimum value of duty factor

0%

15

what happens to the speed of sound in a medum when the bulk modulus of the medium decreses

slower

16

sound intensity is decreased by 75%. how many decibels of attenuation is this

6db

17

if a 5MHz sound wave is traveling in the russues listed below, which will have the longest wavelength? fat, air, muscle, bone

bone

18

what is the approxomate attenuation coefficient of 1

0.5dB/cm

19

ipedance is the ____ of _______ and ________

product, prpagation speed, density

20

for soft tissue, the approximate attenuation coefficient in dB/cm is equeal to 1/2 _____ in _________

freq, MHz

21

as the impendances of 2 media become vastly different the

reflection increases

22

the angle between an US pulse and the boundry between two madia is 56 degrees, this is called

oblique incidence

23

refraction only occurs if there are

obligue incidence and diff propagation speeds

24

with normal incidence what factors affect refraction of US? propagation speeds, frequencies, attenuation coefficients, none of the above

non of the above

25

true or false, with right angle incidence, reflections are alwayus generated at a boundry if the propagation speeds of the media are different

false

26

________ is a redirection of US in many directions uniformly as a result of rough boundary between 2 media

rayleigh scattering

27

under which of the following conditions is axial res umproved? decreased spatial pulse length, decreased pulse amplitude, decreased imaging depth, decreased pixel size, decreased beam diameter

decreased spatial pulse length

28

the most likely amount of refelction at a boundry between soft tussies is? 1%, 22%, 34%, 99%

1%

29

the most typical amount of transmission at a boundary in biologic media is? 1%, 22%, 34%, 99%

99%

30

sound is traceling from medium 1 to medium 2, propagation speeds of M1 and M2 are 1,600m/s and 1,500m/s, there is oblique incidence

angle of incidence = angle of refelction

31

t or f, doppler shifts always occur if the sound source and receiver are in motion

f

32

which of the following is associated with power mode doppler? poor temporal resolution and flash artifact, lower sensitivity and good temporal resolution, high sensiticity and high frame rates, flash artifact and reduced sensitity, good temporal resolution and flash artifact

poor temporal res and flash artifact

33

the doppler shift is a measure of

difference between incident and refelcted freq

34

in an analog scan concerter what component stores the image data

dielectric matrix

35

t or f, shadowing may result from high amounts of reflection of US energy

t

36

typical vaule of a period

.06 to .5 micro sec

37

period is

the time to complete a single cycle, start of one cycle to start of the next, units are time

38

frequency is

number of certain events that occur in a particular time duration

39

typical freq in US

2MHz to 15MHz

40

US freq

> 20,000Hz

41

audable

20Hz to 20,000Hz

42

infrasound

43

amplitude

the difference between the average value and the max value of an acoustic variable

44

units of amplitude

those of the acoustic variables

45

power

the rate that work is perfomred or the rate of energy transfer

46

units for power

watts

47

rlationship between power and amplitude

power is proportional to the waves amplitude squared

48

intenisty

the concetration of energy in a sound beam

49

how to calculate intensity

the beams power divided by the beams cross sectional area

50

units of intensity

watts/cm squared

51

intensity is directly related and proportional to

power

52

how to calculate intensity

amplitude squared

53

what is the lenghth or distance of a single cycle

wavelength

54

wavelength is determined by

both the sound source and the medium

55

typical value of wavelength in soft tissue

o.1 to 0.8 mm

56

how to calculate wavelength

wavelength = prop speed / freq

57

average speed of sound in soft tissue

1.54km/s = 1.540m/s = 1.54mm/micro sec

58

sound in a slow medium as a ______ wavelength

short

59

sound in a fast medium as a _______ wavelength

long

60

bulk modulus is the same as

stiffness

61

equeation for speed

speed = freq x wavelength

62

if the intensity remains the same while the power is doubled, what happends to the beam area

doubled

63

which of the following waves will have the shortest wavelength? low freq in a fast medium, low freq in a slow medium, high freq in a fast medium, high freq in a slow medium

high freq in a slow medium

64

a collection of cycles that travel together

pulse

65

the time from the start of a pulse to the end of that pulse (actual time that that pulse is on)

pulse duration

66

typical valuse of pulse duration in US

0.5 to 3 micro secs

67

in US a pulse is comprised of _______ cycles

2 to 4 cycles

68

pulse duration equation

# of cycles in a pulse x perior

or

# of cycles in a pulse / freq (MHz)

69

pulse repetition period is

time from the sart of one pulse to the start of the next pulse

70

typical values for PRP

100 micro sec to 1 msec

71

PRP is directly related to

imaging depth

72

PRF is

the number of pulses that occur in one sec, unit is Hz

73

typical PRF valuse in US

1 to 10kHz

74

PRF is inversly related to

imaging depth

75

duty factor is

the % of time that the system transmits sound

76

shallow imaging

high PRF
high duty factor
short PRP

77

deep imaging

low PRF
low duty factor
long PRP

78

spatial pulse length is

the length or distance that an entire pulse occupies in space. The distance from the start to the end of one pulse

79

spatial pulse length determines ________ resolution

axial
shorter pulses create higher quality images

80

typical value for spatial pulse length

0.1 to 1mm

81

def of intensity

the concentration of power in a beam

82

peak

max value

83

average

mean value

84

spatial

distance or space

85

temporal

all time, transmit and receive

86

pulse

only time pulse exists, transmit time

87

most important intensity regarding bioeffects

SPTA

88

_______ can be reported in various ways in respect to time and space

intensities

89

intensity in the key parameter in regards to

bio effects

90

3dB is ___ bigger

two times bigger

91

10dB is _____ bigger

ten times bigger

92

a signals power increases from 1 watt to 100 watts, express in dB

100dB

93

100% pwer with 0dB change setting to 25% what are the dB

-6dB

94

unit for attenuation

dB

95

total attenuation increases with

higher freq and longer path length

96

three componenets of attenuation

reflection
absortion
scattering

97

attenuation in ______ is similar to soft tissue

blood

98

types of reflection

specular-smooth surface, back in one direction

diffuse or backscatter-rough boundry same size as wavelength

rayleigh- irregular boudary smaller than wavelength

99

rayleigh scattering

chaotically redirected in all directions, higher freq more rayleigh, related to freq

100

what would cause rayleigh scattering

red blood cell