Ch 15: Displays and Image Processing

Question 1

Bistable images are composed of how many shades?

Answer 1

two: black and white

Question 2

What two user controls can alter characteristics of displayed images?

Answer 2

contrast and brightness

Question 3

This determines the range of brilliancies withing the displayed image.

Answer 3

contrast

Question 4

T/F? Bistable images are high contrast.

Answer 4

true

Question 5

This determines the brilliance of the displayed images

Answer 5

brightness

Question 6

This translates the information from the spoke format into the video format.

Answer 6

scan converter

Question 7

These ‘real world’ numbers have a continuous range of values.

Answer 7

analog

Question 8

These ‘computer’ numbershave only discrete values.

Answer 8

digital

Question 9

This is a funnel-shaped vacuum tube with an electron gun located within its smaller end.

Answer 9

analog scan converter

Question 10

These charged particles contain image information.

Answer 10

electrons

Question 11

This is in the larger end of the electron gun where the electrons are stored.

Answer 11

dielectric matrix or silicon wafer

Question 12

This is when stored charges on the silicon wafer dissipate over time.

Answer 12

image fade

Question 13

This is caused by switching between read and wrtie modes.

Answer 13

image flicker

Question 14

This is when picture quality depends on many factors including length of use, room temperaure, and humidity.

Answer 14

instability

Question 15

This is when an image degrades as the device ages.

Answer 15

deterioration

Question 16

Why are analog scanners now obsolete?

Answer 16

1. image fade
2. image flicker
3. instability
4. deterioration

Question 17

This is the process of converting images into numbers.

Answer 17

digitizing

Question 18

This is the consistent gray scale quality throughout an image.

Answer 18

uniformity

Question 19

This is how an image does not fade or drift.

Answer 19

stability

Question 20

This is when an image is not affected by age or heavy use.

Answer 20

durabiilty

Question 21

What are the advantages of digital scan converters?

Answer 21

1. uniformity
2. stability
3. durability
4. speed
5. accuracy

Question 22

Two important elements of digital scan converters are…

Answer 22

1. pixel

2. bit

Question 23

Pixel comes from the words…

Answer 23

picture element.

Question 24

This is the smallest building block of a digital picture.

Answer 24

pixel

Question 25

The entire pixel is how many shades of gray?

Answer 25

one

Question 26

This is the number of picture elements per inch.

Answer 26

pixel density

Question 27

Higher pixel density is achieved with __ pixels per inch and __ pixels.

Answer 27

many, smaller

Question 28

The word 'bit' is derived from the terms...

Answer 28

binary digit.

Question 29

A bit is __, having a value of 1 or 0.

Answer 29

bistable

Question 30

This is a group of eight bits of computer memory.

Answer 30

byte

Question 31

This is consists of two bytes or 16 bits.

Answer 31

word

Question 32

More bits per pixel give you __ shades of gray and __ contrast resolution.

Answer 32

more, improved

Question 33

To determine the number of gray shades represented by a cluster of bits...

Answer 33

2^# of bits

Question 34

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

Answer 34

2 x 2 x 2 x 2 x 2 = 32

Question 35

This converts the electrical signals from analog to digital form.

Answer 35

analog-to-digital (A-to-D) converter

Question 36

Any processing of the reflected signals before storage is called...

Answer 36

preprocessing.

Question 37

Any processing after storage in the digital scan converter is called...

Answer 37

postprocessing

Question 38

This translates the digital signals back into analog form.

Answer 38

digital-to-analog (D-to-A) converter

Question 39

T/F? Preprocessing alters the image data forever and cannot be reversed or undone.

Answer 39

true

Question 40

Any alterations to a frozen image must be...

Answer 40

postprocessing.

Question 41

This can improve visualization of detail by enlarging a portion of the screen.

Answer 41

Magnification (zoom)

Question 42

This kind of magnification happens after the image data is stored in the scan converter.

Answer 42

Read magnification

Question 43

T/F? In read magnification, the ROI is rescanned.

Answer 43

FALSE, not rescanned

Question 44

T/F? In read magnification, the number of pixels or scan lines in the magnified image is the same as in the original image.

Answer 44

True

Question 45

Are the pixels smaller or larger in read magnification?

Answer 45

Larger

Question 46

This kind of magnification is applied during data acquisition, before storage in the scan converter.

Answer 46

Write magnification

Question 47

T/F? In write magnification, the ROI is rescanned.

Answer 47

True

Question 48

T/F? The number of pixels and scan lines in ROI write magnification stay the same.

Answer 48

FALSE, they are greater than the original image.

Question 49

T/F? The increased number of pixels in ROI write magnification improves spatial resolution.

Answer 49

True

Question 50

T/F? With write magnification, spatial resolution may be improved if the bottom of the ROI is shallower than the original images depth of view.

Answer 50

FALSE, temporal resolution

Question 51

This is a sophisticated method of improving image quality within the context of bioeffects.

Answer 51

Coded excitation

Question 52

Where does coded excitation occur?

Answer 52

In the pulser

Question 53

T/F? Coded excitation creates very short sound pulses containing a wide range of frequencies.

Answer 53

FALSE, very long sound pulses

Question 54

This is a method of using info from several different angles to produce a single image.

Answer 54

Spatial compounding

Question 55

The Limitations of spatial compounding are...

Answer 55

1. Reduced frame rate | 2. Reduced temporal resolution

Question 56

T/F? Spatial compounding is available only with phased array transducers.

Answer 56

True

Question 57

This is an advanced technique that reduces speckle artifact and noise in ultrasound images.

Answer 57

Frequency compounding

Question 58

With frequency compounding, the reflected signal is divided into sub bands of __ , and an image is created from each __

Answer 58

Limited frequencies, sub band

Question 59

This image processing method makes pictures look sharper.

Answer 59

Edge enhancement

Question 60

This image processing technique continues to display info from older images.

Answer 60

Temporal compounding (persistence, temporal averaging)

Question 61

The primary limitation of persistence is a...

Answer 61

Reduction in the displayed frame rate.

Question 62

T/F? Persistence is most effective with slowly moving structures.

Answer 62

True

Question 63

How do persistence and spatial compounding differ?

Answer 63

Persistence uses images all from the same view, and spatial compounding images are all from different angles.

Question 64

This is a method of constructing new simulated data points to fill in the gaps of sector shaped images.

Answer 64

fill-in interpolation

Question 65

This imaging technique is related to the mechanical properties of tissue, particularly how the tissue deforms following the application of a force.

Answer 65

elastography

Question 66

PACS stands for...

Answer 66

Picture Archiving Communications System

Question 67

What are the three main advantages of a PACS?

Answer 67

1. instant access to archived studies 2. no degradation of data 3. the ability to email images and reports to remote sites

Question 68

What is the primary digital storage device used in PACS?

Answer 68

the computer hard drive

Question 69

DICOM stands for...

Answer 69

Digital Imaging Computers in Medicine

Question 70

This is a set of rules or protocols that allows imaging systems to share information on a network.

Answer 70

DICOM