14 Displays

Question 1

What are characteristics of a bistable display?

Answer 1

2 choices - black or white
On or off
High contrast
Narrow dynamic range
Poor contrast resolution

Question 2

What are characteristics of a gray scale display?

Answer 2

Many shades of gray
Multiple levels
Low contrast
Wide dynamic range
Good contrast resolution

Question 3

What are the controls of the display?

Answer 3

Brightness - brilliance of image

Contrast - range of brilliancies that are displayed

Question 4

What is analog?

Answer 4

Real world - variable attains a continuum of values

Question 5

What is digital?

Answer 5

Computer world - variable attains only discrete values

Question 6

What are scan converters?

Answer 6

Changes data format from penetrations (spokes) to horizontal lines of a display

Question 7

What is a pixel?

Answer 7

Smallest element of a digital picture

Question 8

What is pixel density?

Answer 8

Pixels per inch - more pixels = more detail, spatial or detail resolution

Question 9

What determines spatial resolution on a digital display?

Answer 9

Pixel density

Question 10

What is spatial resolution related to?

Answer 10

Number of lines per frame

Question 11

What is a binary digit (bit)?

Answer 11

Smallest amount of digital storage

Question 12

What is better with more bits per pixel?

Answer 12

Contrast resolution

Question 13

What is a binary number?

Answer 13

Group of bits

Question 14

What is a byte?

Answer 14

Group of 8 bits

Question 15

What is a word?

Answer 15

2 bytes (16 bits)

Question 16

How do you calculate the number of gray shades that a collection of bits can represent?

Answer 16

1. Find out how many bits are assigned to each pixel
2. Multiply the # 2 by itself the same # of times as there are bits
   2^n, n = # of bits

Question 17

What is image preprocessing?

Answer 17

Manipulating the data before storage in the scan converter and cannot be reversed
TGC
Log compression
Write magnification
Fill-in interpolation
Persistence (frame averaging)
Spatial compounding

Question 18

What is log compression?

Answer 18

Ability of humans to see gray scale differences in anatomic structures - lowers high level echoes and boosts low level echoes

Question 19

What is image postprocessing?

Answer 19

Manipulating data after it has been stored in the scan converter memory but prior to display
Read magnification
3-D rendering

Question 20

What type of images is postprocessing used?

Answer 20

Frozen images

Question 21

What is an analog-to-digital converter?

Answer 21

Analog signal (electrical signals by the PZT) converted into digital form for input into the scan converter

Question 22

What is digital-to-analog conversion?

Answer 22

Conversion of info in scan converter to analog form to display

Question 23

Describe flow of information through an ultrasound system.

Answer 23

Master Synchronizer >
Pulser >
Beam Former (beam steering) >
Transducer >
Receiver (preprocessing) >
Scan Converter (A to D > Digital data > D to A) >
Display >
Image Archive