Ch 15 Flashcards Preview

DMSO Physics 2 > Ch 15 > Flashcards

Flashcards in Ch 15 Deck (50):
1

Bistable

2 shades; black and white High Contrast

2

Gray Scale

Multiple levels of gray Low Contrast

3

Analog

"real world" numbers

unlimited # of choices

continuous values

4

Digital

"computer" numbers

limited choices

discrete values

5

Contrast

determines the range of brilliance within the displayed image

6

Brightness

determines the range of the displayed image

7

Scan convertor

translates the information from the spoke format into the video format

8

Spatial resolution

image detail

9

Disadvantages of analog scan convertors

image fade

image flicker

instability

deterioration

10

Advantages of digital scan convertors

Uniformity

Stability

Durability

Speed

Accuracy

11

Pixel

smallest building block of a digital picture

12

Pixel Density

Number of picture elements per inch

13

Low Pixel Density

pixels per inch

size of pixels

detail of image

spatial resolution

few pixels per inch

larger pixels

less detailed image

lower spatial resolution

14

High Pixel Density

pixels per inch

size of pixels

detail of image

spatial resolution

many pixels per inch

smaller pixels

more detailed image

higher spatial resolution

15

Bit

smallest amount of computer memory

16

Byte

group of eight bits of computer memory

17

Word

computer memory consists of two bytes or 16 bits

18

Contrast Resolution

gray shades

19

Fewer Bits per Pixel

shades of gray

contrast resolution

fewer shades of gray

degraded contrast resolution

20

More Bits per Pixel

shades of gray

contrast resolution

more shades of gray

improved contrast resolution

21

Calculating the shades of gray

2^ number of bits

22

Pixels vs Bits

Pixel

image element

image detail

spatial resolution

23

Pixels vs Bits

Bits

computer memory

gray shades

contrast resolution

24

Analog to digital converter

Analog -> analog to digital converter -> Digital memory -> digital to analog converter -> Analog

25

Preprocessing

manipulating before storage in the scan convertor

TGC , log Compression , write magnification, persistence, spatial compounding, edge enhancement, fill-in interpolation

26

Postprocessing

manipulating after storage in the scan convertor

any change after freeze frame, black/white inversion, read magnification, contrast variation, 3-D rendering

27

Read Magnification

uses old data

postprocessing

larger pixel size

same # of pixels as in the original ROI

unchanged spatial resolution

unchanged temporal resolution

28

Write Magnification

acquires new data

preprocessing

identical pixel size

more pixels that in the original ROI

improves spatial resolution

may improves temporal resolution

29

Coded Excitation

method of improving image quality

creates long sound pulses containing a wide range of frequencies

occurs in pulser

30

Advantages of Coded Excitation

higher signal to noise ratio

improved axial resolution

improved spatial resolution

improved contrast resolution

deeper penetration

31

Spatial Compounding

method of using different angles to produce a single image

reduce speckle and shadowing

used with electrical steering / phased array only

32

Frequency Compounding

reduce speckle and noise artifact

reflected sound wave is divided into subbands

 

33

Edge Enhancement

makes image look sharper

works by increasing image contrast

creates sublte bright and dark highlights around edges to make them look more defined

34

Temporal Compounding or Persistence

makes image smoother

"super impose"

 

35

Fill-in Interpolation

predicts what information lies between the gaps and improves spatial resolution

preprocessing

 

36

Elastography

measure how dense something is and have mechanical properties

 

37

PACS

Picture Archiving and Communications System

Stored digitally

 

38

DICOM

Digital Imaging and Computers in Medicine

set of rules, or protocols, that allows imaging system to share info on a network

assure's communicatoin for future devices

39

Recording and Archiving Techniques: Paper Media Examples

charts from pen writers

40

Recording and Archiving Techniques: Paper Media Advantages

portability does not require a device to read

41

Recording and Archiving Techniques: Paper Media Disadvantages

bulky, hard to store difficult to make copies cant display dynamic images

42

Recording and Archiving Techniques: Magnetic Media Examples

computer discs computer memory magnetic tape video tape

43

Recording and Archiving Techniques: Magnetic Media Advantages

able to store large amounts of info efficiently can store and play dynamic can record color

44

Recording and Archiving Techniques: Magnetic Media Disadvantages

can be erased by strong magnetic fields

45

Recording and Archiving Techniques: Chemically Mediated Photographs Examples

photographs flat films multiformat camera film

46

Recording and Archiving Techniques: Chemically Mediated Photographs Advantages

High resolution accepted in the medical community can produce color images

47

Recording and Archiving Techniques: Chemically Mediated Photographs Disadvantages

bulky, difficult to store and retrieve requires chemical processing artifacts can arise from dirt pr chemical contamination

48

Recording and Archiving Techniques: Optical Media Examples

laser discs compact discs

49

Recording and Archiving Techniques: Optical Media Advantages

store huge amounts of data inexpensive not erased by exposure to magnetic field

50

Recording and Archiving Techniques: Optical Media Disadvantages

requires a display system no standardized format for image display and storage