Chapter 15

Question 1

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

Answer 1

Bistable

Question 2

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

Answer 2

Grayscale

Question 3

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

Answer 3

Contrast

Question 4

____ the lightness or darkness of an image.

Answer 4

Brightness

Question 5

Define the role of the scan converter.

Answer 5

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

Question 6

Old technology used ____ scan converters.

Answer 6

Analog

Question 7

New technology uses ____ scan converters

Answer 7

Digital

Question 8

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

Answer 8

Analog

Question 9

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

Answer 9

Digital

Question 10

What is the analog scan converter?

Answer 10

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

Question 11

Analog scan converters have ____ spatial resolution.

Answer 11

Excellent

Question 12

Advantages of a digital scan converter:

Answer 12

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

Question 13

Two important parts of a digital scan converter are:

Answer 13

Pixel and bit

Question 14

The ____ is the smallest building block of a digital picture

Answer 14

Pixel

Question 15

Each ____ is a single shade of grey.

Answer 15

Pixel

Question 16

Pixel ____ is the number of pixels per inch

Answer 16

Density

Question 17

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

Answer 17

High; Size

Question 18

A ____ is the smallest amount of computer memory

Answer 18

Bit

Question 19

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

Answer 19

0 or 1

Question 20

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

Answer 20

Binary number

Question 21

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

Answer 21

8

Question 22

A ____ is two bytes (16 bits)

Answer 22

Word

Question 23

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

Answer 23

Gray shades

Question 24

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

Answer 24

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

Question 25

What is another name for digital number?

Answer 25

Binary number

Question 26

Any processing before storage is called ____.

Answer 26

Preprocessing

Question 27

Examples of preprocessing are:

Answer 27

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

Question 28

Any processing after storage is called ____.

Answer 28

Postprocessing

Question 29

Preprocessing ____ be reversed once performed; postprocessing ____ be reversed

Answer 29

Cannot; Can

Question 30

Examples of postprocessing are:

Answer 30

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

Question 31

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

Answer 31

Magnification

Question 32

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

Answer 32

1. Read magnification 2. Write magnification

Question 33

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

Answer 33

Read

Question 34

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

Answer 34

Write

Question 35

List 6 points that describe read magnification.

Answer 35

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

Question 36

List 6 points that describe write magnification.

Answer 36

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)

Question 37

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

Answer 37

Coded excitation

Question 38

Where does coded excitation occur?

Answer 38

In the pulser

Question 39

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

Answer 39

Spatial compounding

Question 40

Spatial compounding will ____ frame rate and temporal resolutions.

Answer 40

Reduce

Question 41

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

Answer 41

Frequency compounding

Question 42

Edge enhancement make the picture look ____.

Answer 42

Sharper

Question 43

Another term for temporal compounding is ____ or ____ ____.

Answer 43

Persistence or temporal averaging.

Question 44

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

Answer 44

Temporal compounding

Question 45

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

Answer 45

Smoother; Reduced

Question 46

What is fill-in interpolation?

Answer 46

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.

Question 47

Fill-in interpolation is a ____ function.

Answer 47

Preprocessing

Question 48

What does PACS stand for?

Answer 48

Picture Archiving and Communications System

Question 49

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

Answer 49

PACS

Question 50

What does DICOM stand for?

Answer 50

Digital Imaging and Computers in Medicine

Question 51

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

Answer 51

DICOM

Question 52

____ ____ are charts from pen writers.

Answer 52

Paper media

Question 53

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

Answer 53

Magnetic media

Question 54

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

Answer 54

Chemically mediated photographs

Question 55

____ ____ are laser discs, compact discs.

Answer 55

Optical media

Question 56

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

Answer 56

PACS systems

Question 57

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

Answer 57

Magneto-optical storage