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Ultrasound Physics > Chapter 15 > Flashcards

Chapter 15 Flashcards

Displays and Image Storage

1
Q

____ images are composed of only two shades, black and white.

A

Bistable

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2
Q

____ images are composed of black, white and many shades of grey in between.

A

Grayscale

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3
Q

____ the amount of black, white an grey in an image.

A

Contrast

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4
Q

____ the lightness or darkness of an image.

A

Brightness

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5
Q

Define the role of the scan converter.

A

Stores information first and later displays it. It changes the format of the data from spoke format into video format.

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6
Q

Old technology used ____ scan converters.

A

Analog

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7
Q

New technology uses ____ scan converters

A

Digital

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8
Q

____ numbers are “real world” numbers (1, 2, 3, 4, 5…). They have an unlimited and continuous range of values.

A

Analog

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9
Q

____ numbers are associated with computer devices. They use discrete values. Finite number of choices.

A

Digital

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10
Q

What is the analog scan converter?

A

The first form of scan converter - converts info from analog to digital.

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11
Q

Analog scan converters have ____ spatial resolution.

A

Excellent

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12
Q

Advantages of a digital scan converter:

A
  1. Uniformity – consistent greyscale quality of image
  2. Stability – image does not fade or drift
  3. Durability – image is not affected by age or heavy use
  4. Speed – nearly-instant processing
  5. Accuracy – error-free
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13
Q

Two important parts of a digital scan converter are:

A

Pixel and bit

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14
Q

The ____ is the smallest building block of a digital picture

A

Pixel

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15
Q

Each ____ is a single shade of grey.

A

Pixel

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16
Q

Pixel ____ is the number of pixels per inch

A

Density

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17
Q

Spatial resolution improves with ____ pixel density and decreased pixel ____.

A

High; Size

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18
Q

A ____ is the smallest amount of computer memory

A

Bit

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19
Q

A bit is bistable, it has a value of either ____ or ____.

A

0 or 1

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20
Q

A ____ ____ is a group of bits. Made up of 1’s and 0’s.

A

Binary number

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21
Q

A byte is a group of ____ bits of computer memory.

A

8

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22
Q

A ____ is two bytes (16 bits)

A

Word

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23
Q

To determine the number of ____ ____, multiply the number 2 by itself the same number of times as there are bits.

A

Gray shades

24
Q

How many shades of gray are displayed with 5 bits of memory?

A

2^5 = 2 x 2 x 2 x 2 x 2 = 32 shades of gray

25
Q

What is another name for digital number?

A

Binary number

26
Q

Any processing before storage is called ____.

A

Preprocessing

27
Q

Examples of preprocessing are:

A

TGC’s, compression (2D), write magnification, persistence, spatial compounding, edge enhancement, and fill-in interpolation.

28
Q

Any processing after storage is called ____.

A

Postprocessing

29
Q

Preprocessing ____ be reversed once performed; postprocessing ____ be reversed

A

Cannot; Can

30
Q

Examples of postprocessing are:

A

Changes to a still image, black/white inversion, read magnification, 3-D rendering.

31
Q

____ (a.k.a. zoom) enlarges a portion of the image to fill the entire screen.

A

Magnification

32
Q

There are two different forms of magnification used in ultrasound systems:

A
  1. Read magnification
  2. Write magnification
33
Q

____ magnification occurs after image storage in the scan converter. This is postprocessing.

A

Read

34
Q

____ magnification occurs during data acquisition before image storage in the scan converter. This is preprocessing.

A

Write

35
Q

List 6 points that describe read magnification.

A
  1. Uses old data
  2. Postprocessing
  3. Larger pixel size
  4. Same # of pixels as the original ROI
  5. Unchanged spatial resolution
  6. Unchanged temporal
36
Q

List 6 points that describe write magnification.

A
  1. Acquires new data
  2. Preprocessing
  3. Identical pixel size
  4. More pixels than in the original ROI
  5. Improved spatial resolution
  6. May improve temporalresolution resolution (fewer scan lines)
37
Q

____ ____ creates very long sound pulses which contain a wide range of frequencies.

A

Coded excitation

38
Q

Where does coded excitation occur?

A

In the pulser

39
Q

During ____ ____, ultrasound information is obtained from different angles and combined to form single image.

A

Spatial compounding

40
Q

Spatial compounding will ____ frame rate and temporal resolutions.

A

Reduce

41
Q

____ ____ is an advanced technique used to reduce speckle artifact and noise by dividing the reflected signal into “sub-bands” of limited frequencies.

A

Frequency compounding

42
Q

Edge enhancement make the picture look ____.

A

Sharper

43
Q

Another term for temporal compounding is ____ or ____ ____.

A

Persistence or temporal averaging.

44
Q

____ ____ is a technique which uses a number of previous frames that are superimposed on the current frame.

A

Temporal compounding

45
Q

Temporal compounding produces a ____ image with ____ noise, higher signal to noise ratio, and improved image quality

A

Smoother; Reduced

46
Q

What is fill-in interpolation?

A

A sophisticated computer program that predicts the gray scale levels of missing data by using the gray scale levels of neighboring pixels to predict the missing info.

47
Q

Fill-in interpolation is a ____ function.

A

Preprocessing

48
Q

What does PACS stand for?

A

Picture Archiving and Communications System

49
Q

____ describes labs in which images and other medical info are digitized and stored on a large computer network.

A

PACS

50
Q

What does DICOM stand for?

A

Digital Imaging and Computers in Medicine

51
Q

____ is a set of rules or protocols that allows and imaging system to share information on a network.

A

DICOM

52
Q

____ ____ are charts from pen writers.

A

Paper media

53
Q

____ ____ are computer discs, computer memory, magnetic tape, video tape.

A

Magnetic media

54
Q

____ ____ ____ are photographs, flat films, multiformat camera film.

A

Chemically mediated photographs

55
Q

____ ____ are laser discs, compact discs.

A

Optical media

56
Q

____ ____ are picture archiving and communications system. Images and reports are digitized and stored on a large computer network.

A

PACS systems

57
Q

____-____ ____ is a combination of magnetic and laser (optical) technology. Often used to store/archive PACS studies.

A

Magneto-optical storage

Ultrasound Physics (11 decks)

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