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Flashcards in SPI Review 4 Deck (101):
1

odd field are written by the elctron beam, then the even feild are written, this is called

interlaced display

2

how long does it take to create one display feild

1/60th of a sec

3

on typical tv a complete image is created in _____ and the frame rate is ______

1/30th of a sec
30Hz

4

only 2 choices, white or black, on or off, high contrast narrow dynamic range, poor contrast res

bistable

5

many levels of brightness, the assignment of diff gray shades for each echo amplitude, diff colors represent diff signal strengths, low contrast, wide dynamic range, improved contrast res

gray scale

6

determines the brilliance of the signals displayed

brightness

7

determines the range of brilliancies that are displayed, bistable images are high contrast

contrast

8

controls

brightness
contrast

9

real world, a variable attains a continuum of values

analog

10

computer world, a variable attains only discete values

digital

11

"the numbers"

digital image data

12

the smallest element of a digital picture

pixel

13

the greater the pixel density the greater the detail in the imaged, this is called

spatial detail resolution

14

spatial res of a crt is determined by

the number of tv lines per frame

15

a group of __ is assigned to each pixel to store the gray scale color assigned to that ____

bit
pixel

16

the more bits per pixel, the more shades of gray and the better the _______

contrast resolution

17

the smallest amount of digital storage, a group of bits, a series of 1 and 0

binary digit

18

a bit is _____ it has a value of either 0 or 1

bistable

19

a group of 8 bits

a byte

20

2 bytes =

16 bits

21

binary numbers are based on

2

22

decimal numbers are based on

10

23

how to calculate the number of gray shades that a collection of bits can represent

find out how many bits are assigned to each pixel

x the number 2 by itself the same number of times as there are bits

24

the number of gray shades displayed by

"n" bits is 2n

25

what is the number of shades that can be represented by 10 bits

2 to the 10th

1024

26

preprocessing

log compression
fill in interpolation
spatial compouding
TGC
write magnification
persistant time gain?

27

related to the ability of humans to see the gray scale diff in anatomic structures, lower the high level echoes and boosts the low level echoes. the image dattas dynamic range is reduced

log compression

(pre processing, controlled by sonographer)

28

performed on frozen images

post processing

29

electrical signals from the transducer are ____ and must be converted into _______

analog
digital form

30

occurs after the image data is in the scan converter, is not re scanned and reads only part of the old data from the original image

read magnification

when the size of an image increases, if the number of pixels is unchanged, pixel size increases ****

31

occurs upon acquisition of the US reflections, preprocessing, system re scans region of interest

write magnification

when the size of an image increases, if pixel size is unchanged, the number of pixels increase***

32

improves image detail (spatial res) by filling in the missing data

fill in interpolation

example, the edges of a circular structure will be better defined**

33

scan lines are steered by the transducer in diff directions so structures are interrogated by more than one pulse

spatial compounding

34

in spatial compounding

speckle and clutter are reduced

spatial res is iimproved

temp res and frame rate are reduced

shadows are reduced or eliminated

35

only _____ ______ trans use spatial compounding since they are steered ______

phased array
electronically

36

in spatial compounding the frames are ______ improving ____ __ _____ _____

averaged

signal to noise ratio

37

the averaging of previous frames to the displayed image, adds a "history" to the current image

persistence aka temporal averaging

38

persistence good for

smoother image

reduces noise

stationary or slow miving structures

39

edge enhancement is used for

emphasize the boundary between diff tissues and distinguish interfaces between structures w diff gray scale characterisitic

40

the ratio of the largest to smallest signal strength that each component processes

dynamic range

41

the dynamic range of the display indicates the number of

gray shades

42

narrow dynamic range

few choices
bistable (Black and white)

high contrast

43

wide dynamic range

many choices

gray scale

low contrast

44

units for dynamic range

dB, a relatice measurement

45

the dynamic range of a signal ____ the more it is processed

decreases

46

transducers dynamic range is the ____ of all the systems components

greatest

47

the ___ _____ has the lowest dynamic range

recording device

48

PACS stands for

picture archiving and communications system

49

combines magnetic and laser technology

magneto optical

50

digital imaging and communications in medicine provides standards for medical imaging networks

DICOM

51

fluid moving at a constant speed or velocity

steady flow

52

fluid miving with a variable velocity, accelerates and decelerates, results from cardiac contraction

pulsatile flow

53

normal pulsatile flow

60/min

54

fluid moving with a variable velocity, accelerates and decelerates, results from respiration

phasic flow

55

normal phasic flow

15/min

56

the volume of a moving fluid, how much

flow

57

the speed or swiftness of moving fluid, how fast

velocity

58

_____ flow may have parabolic or plug patterns

laminar

59

layers travel at individual speeds with _______ flow

parabolic flow

60

in parabolic flow the speed is the highest at the

center of the lumen

61

flow found in normal physiologic states

laminar

62

small regions of laminar flow will have _____ _____ and _____ _______ ______

similar velocities and narrow doppler specta

63

chaotic flow in many directions and speeds

turbulents flow

64

turbulent flow is associated with

cardiovascular pathology and increased velocities

65

small regions of turbulent flow have vastly different volovitites

dopper spectral broadeneing

66

flow energy is lost and converted to

sound-murmurs or bruits

vibrations-thrill

67

a swirling pattern of rotational flow

vortex

68

eddy currents are

turbulent flow

69

turbulence may be identified as

spectral broadening

70

a unitless number indicating whether flow is laminar or turbulent

reynolds number

71

reynolds number for turbulent flow

>2,000

72

reynolds number for laminar flow

73

blood flows when the total fluid energy at one location differs from the total fluid energy at another location, this is called

energy gradient

74

energy associated with moving objects

kinetic energy

75

a form of potential or stored energy that has the ability to perform work

pressure energy

76

energy is imparted to blood by the contraction of the _____ _____ called ______

left ventricle

systole

77

three forms of energy loss

frictional loss

viscous loss

inertial loss

78

the conversion of other forms of energy into heat

friction

ex. blood sliding across vessel walls

79

describes the thickness of fluid

viscosity

units poise**

80

causes increased blood viscosity

thick fluid

increased hematocrit or hemoglobin (polythemia or erythrocytosis)

81

relates to the tendency of a fluid to resist changes in it velocity, objects at rest tend to stay at rest

inertia (inertial loss)

82

inertial loss results from

pulsatile flow, both acceleration and deceleration

velocity changes at a stenosis

83

a narrowing or irregularity in a lumen

stenosis

84

stenosis causes

changes in flow direction

increased velocity in the stenosis

turbulence at exit

pressure gradient accross the stenosis

arterial flow loses its pulatile nature and becomes more continuous

85

highest velocity at the point of max narrowing, pressure is the lowest here

bernoullis principle

86

factors that determine resistence

radious of lumen (most imiportant)

length

viscosity of fluid

87

the weight of the blood pressing on the vessel from heart level to the point of measurement

hydrostatic pressure

88

pressure measured is greater than circulatory pressure cause hydrostatic pressure is positive

below the heart

89

pressure measured is less than circulatory pressure because hydrostatic pressure is negative

above the heart

90

there is no column of blood pressing on the vessels of the body, hydrostatic pressure is 0 at all locations

supine position

pressures measured are true circulatory pressures

91

standing position

hand extended above heart the pressure is

50mmHg

92

standing

head pressure is

30mmHg

93

heart level pressure while standiing

0mmHg

94

at anke pressure is while standing

100mmHg

95

while standing pressure at the knee is

75mmHg

96

calculate pressure measurement

subtract hydrostatic from systolic pressure

97

vessel collapse, when opposing vessels walls touch each other, when blood pressure is 0mmHg

coaptation

98

during inspiration the diaphragm

diaphragm presses into abd

99

during expiration the diaphragm

diaphragm presses into thorax

100

during inspiration

abd pressure increases

venous flow in legs decrease

pressure in thorax decreases

venous return to the heart increases (arms and abd into the thorax)

101

during expiration

abd pressure decreases

venous flow in legs increases

thorax pressure increases

venous return to the heart decreases (arms and abd into the thorax)