Ch. 15 Displays and Image Processing

Question 1

bistable display

Answer 1

bi = two

black and white image

Question 2

grayscale display

Answer 2

multiple levels of brightness such as white, light gray, medium gray etc.

Question 3

__________________ determines the range of brilliancies within the displayed image. Bistable images, in which are only black and white appear, are high ____________________

Answer 3

Contrast determines the range of brilliancies within the displayed image. Bistable images, in which are only black and white, are high contrast.

Question 4

________________________ determines the brilliance of the displayed image

Answer 4

Brightness determines the brilliance of the displayed image

Question 5

_____________________________ which stores information first and later displays it; changes the format of the data (converts from spoke format to video format)

Answer 5

Scan Converter which stores information first and later displays it; changes the format of the data (converts from spoke format to video format)

Question 6

storage of the image information in the scan converter is called ______________

Answer 6

storage of the image information in the scan converter is called writing

Question 7

Later, image data is _________________ from the scan converter for display on the monitor

Answer 7

Later, image data is Read from the scan converter for display on the monitor

Question 8

__________________ numbers are “real world” numbers that are found in our everyday lives.

Answer 8

Analog numbers are “real world” numbers that are found in our everyday lives.

Example: your weight on a scale or the length of a string

Question 9

____________________ numbers are associated with computer devices.

Answer 9

Digital numbers are associated with computer devices

limited choices, discrete values

Question 10

What was the first type of scan converter?

Answer 10

analog scan converter and made gray scale imaging possible

Question 11

How do Analong Scan converters work?

Answer 11

an electron gun shot out electrons which contained the image information. These electrons strike the dielectric matrix/silicon wafer where they are stored. The stored electron charges are read to retrieve image information

Question 12

What is the major benefit of an analog scan converter?

Answer 12

the spatial resolution is excellent

Question 13

Spatial resolution is “___________________”

Answer 13

Spatial resolution is “image detail”

Question 14

What are the 4 limitations of Analog Scan converters:

Answer 14

1. image fade - stored charges on the silicon wafer dissipate over time
2. image flicker - caused by switching between read and write modes.
3. instability - picture quality depends on many factors including length of use, room temperature, and humidity
4. Deteriotation - image degrades as the device ages

Question 15

Digital scan converters use computer technology to convert images into numbers, a process called ________________________

Answer 15

Digital scan converters use computer technology to convert images into numbers, a process called digitizing

Question 16

Advantages of digital scan converters:

Answer 16

• Uniformity: consistent gray scale quality throughout the image
• Stability: does not fade or drift
• Durability: not affected by age or heavy use
• Speed: nearly instant processing
• Accuracy: error-free

Question 17

what are the two important elements of digital scan converters:

Answer 17

1. pixel
2. bit

Question 18

__________________ is the smallest building block of a digital picture

Answer 18

Pixel is the smallest building block of a digital picture

Question 19

_______________________________ is the number of picture elements per inch

Answer 19

Pixel Density is the number of picture elements per inch

Question 20

Spatial resolution and pixel density are ______________________ (unrelated, related, directly related)

Answer 20

Spatial resolution and Pixel density are Directly related (which in higher pixel density = better spatial resolution)

Question 21

low pixel density: ____ pixels per inch, ____ pixels, _____ detailed image, ____ spatial resolution

Answer 21

low pixel density:

• few pixels per inch
• larger pixels
• less detailed image
• lower spatial resolution

Question 22

high pixel density: ____ pixels per inch, ____ pixels, ____ detailed image, ____ spatial resolution

Answer 22

high pixel density:

• many pixels per inch
• smaller pixels
• more detailed image
• higher spatial resolution

Question 23

_______ is a binary digit, the smallest amount of computer memory

Answer 23

Bit is a binary digit, the smallest amount of computer memory

Question 24

A ___________________ is a group of bits and simply a series of zeros and ones, such

Answer 24

A Binary number is a group of bits and simply a series of zeros and ones, such as 0101010011

Question 25

A ____________ is a group of eight bits of computer memory such as 10011111

Answer 25

A *Byte* is a group of eight bits of computer memory such as 10011111

Question 26

A _______________ of computer memory consists of two bytes, or 16 bits

Answer 26

A *Word* of computer memory consists of two bytes, or 16 bits

Question 26

fewer bits per pixel: _______ shades of gray, _____ contrast resolution

Answer 26

fewer bits per pixel: *fewer* shades of gray, *degraded* contrast resolution

Question 27

More bits per pixel: ___________ shades of gray, ______________ contrast resolution

Answer 27

more bits per pixel: *more* shades of gray, *improved* contrast resolution

Question 28

Formula that determines the number of different shades of gray:

Answer 28

2^# of bits

Question 29

5 bits, number of shades =

Answer 29

2 x 2 x 2 x 2 x 2 = 32 shades of gray

Question 30

why do we convert analog to digital data?

Answer 30

digital information is far less susceptible to contamination (the info is converted back to analog before being displayed)

Question 31

What is the 5 step process for converting analog info into digital info and then back again?

Answer 31

1. the *analog-digital-converter* changes the electric signals created during reception from analog to digital format 2. digital info is stored on the computer memory, any processing of reflected signals before storage is *preprocessing* 3. digital info continues to be processed in the digital scan converter, any processing after storage is called *postprocessing* 4. A *digital-analog-converter* changes the digital signals back to analog information to be displayed on the monitor 5. the analog info is presented on the *video display* for interpretation

Question 32

___________________________ is the manipulation of image data before storage in the scan converter

Answer 32

*Preprocessing* is the manipulation of image data before storage in the scan converter

Question 33

____________________________ is the manipulation of image data after storage in the scan converter

Answer 33

*Postprocessing* is the manipulation of image data after storage in the scan converter

Question 34

Time gain compensation, log compression, write magnification, persistence, spatial compounding, edge enhancement, fill-in interpolation are all apart of ________________________________

Answer 34

Time gain compensation, log compression, write magnification, persistence, spatial compounding, edge enhancement, fill-in interpolation are all apart of *Preprocessing*

Question 35

Any change after freeze frame, black/white inversion, read magnification, contrast variation, 3-D rendering are all apart of ___________________________________

Answer 35

Any change after freeze frame, black/white inversion, read magnification, contrast variation, 3-D rendering are all apart of *Postprocessing*

Question 36

what are two forms of magnification?

Answer 36

read magnification, and write magnification

Question 37

____________ magnification occurs after the image data is stored in the scan converter

Answer 37

*Read* magnification occurs after the image data is stored in the scan converter

Question 38

____________ magnfication is applied during data acquisition, before storage in the scan converter

Answer 38

*Write* magnification is applied during data aquisition, before storage in the scan converter

Question 39

__________________________________ is a sophisticated method of improving image quality, that makes the strongest pulse possible within FDA limits, provides higher signal-to-noise ratio, improved axial, spatial and contrast resolution, deeper penetration

Answer 39

*Coded Excitation* is a sophisticzted method of improving image quality, that makes the strongest pulse possible within FDA limits, provides higher signal-to-noise ratio, improved axial, spatial and contrast resolution, deeper penetration

Question 40

coded excitation occurs in the _________________________

Answer 40

coded excitation occurs in the *pulser*

Question 41

higher signal-to-noise ratio, improved axial resolution, improved spatial resolution, improved contrast resolution, and deeper penetration is provided by _____________________________________

Answer 41

higher signal-to-noise ratio, improved axial resolution, improved spatial resolution, improved contrast resolution, and deeper penetration is provided by *coded excitation*

Question 42

__________________________________________ is a method of using sonographic information from several different imaging angles to produce a single image. Reduces speckle and minimizes shadowing artifacts. (is available only with phased array transducers)

Answer 42

Spatial Compounding is a method of using sonographic information from several different imaging angles to produce a single image. - is available only with phased array transducers

Question 43

In general, the more _____________ in the compound acquisition sequence, the better the compound image quality.

Answer 43

In general, the more *frames* in the compound aquisition sequence, the better the compound image quality

Question 44

what are the limitations of spatial compounding?

Answer 44

reduced frame rates and reduced temporal resolution

Question 45

_______________________________ is an advanced technique that reduces speckle artifact and noise in ultrasound images. the reflected signal is divided into sub-bands of limited frequencies, and an image is created from each sub-band. The images from the sub-bands are then combined, or compounded into a single image.

Answer 45

*Frequency Compounding* is an advanced technique that reduces speckle artifact and noise in ultrasound images. the reflected signal is divided into sub-bands of limited frequencies, and an image is created from each sub-band. The image from the sub-bands are then combined, or compounded into a single image.

Question 46

how does frequency compounding affect the image?

Answer 46

reduces speckle artifact and noise

Question 47

_______________ enhancement is an image processing method that makes pictures look sharper by increasing the image contrast in the area immediately around the edge (creates subtle bright and dark highlights on either side of these boundries to make them appear more defined)

Answer 47

*Edge Enhancement* is an image processing method that makes pictures look sharper by increasing the image contrast in the area immediately around the edge - by creating subtle bright and dark highlights on either side of these boundries to make them appear more defined

Question 48

_______________________________, persistence, or temporal averaging, is an image processing technique that continues to display information from older images.

Answer 48

*Temporal Compounding*, persistence or temporal averaging, is an image processing technique that continues to display information from older images.

Question 49

what are the consequences of temporal compounding?

Answer 49

reduced frame rate and temporal resolution

Question 50

What does PACS stand for? What is it?

Answer 50

*Picture Archiving & Communications System* BMI platform configured to facilitate storing, retrieving and distributing medical images

Question 51

What does DICOM stand for and what does it do?

Answer 51

DICOM stands for *Digital Imaging and Computers in Medicine* DICOM is a set of rules, or protocols, that allows imaging systems to share information on a network.