Exposures Chapter 24: Digital Image Processing

Front 1

What is a computer?

Back 1

A device that
processes
information

Front 2

What was the first computer?

Back 2

The first computer
was the abacus (c.
3000 B.C.)

Front 3

Modern computers use what?

Back 3

microchip technology

Front 4

Analog computers handle data composed of....?

Back 4

continuously varying electrical currents.

Front 5

Changes
in voltage represents what?

Back 5

different data

Front 6

Digital computers handle data composed of...?

Back 6

definite quantities of current.

Front 7

Digital computer data is in the form of
electrical current being done what to?

Back 7

turned on or off
(1 or 0)

Front 8

Medical imaging utilizes...?

Back 8

digital
computers

Front 9

Computers use two types of information: being what?

Back 9

Programs and data

Front 10

Programs are what?

Back 10

Programs: the operating instructions for the computer.

Front 11

Programs also Provides specific instructions for calculations
and...?

Back 11

Sequential steps to be followed.

Front 12

Special computer languages are used for
what?

Back 12

Programming

Front 13

Programs are called...?

Back 13

Software

Front 14

The actual computer equipment is referred
to as...?

Back 14

Hardware

Front 15

Our base 10 decimal system used ___through___ to
express numerical values.

Back 15

0-9

Front 16

0= on or off?
1= on or off?

Back 16

0=Off
1=On

Front 17

Each binary number is called a what?

Back 17

Bit

Front 18

Binary numbers express any sized number
by a combination of?

Back 18

0 and 1

Front 19

Binary place
columns increase
by powers of...?

Back 19

Two

Front 20

Adding up the value of places marked by binary 1s give the...?

Back 20

decimal equivalent

Front 21

A “bit” or binary digit equals ___binary number.

Back 21

One

Front 22

An _____ bit word is needed to form the 26 letters in the English alphabet.

Back 22

Eight

Front 23

An eight bit word is called a what?

Back 23

Byte

Front 24

Computer memory is often rated in terms of...?

Back 24

Total byte memory

Front 25

In order to convert analog information (variations of an x-ray beam or light from an image intensifier) to digital information, an ___ is utilized.

Back 25

ADC (analog to digital converter)

Front 26

The ADC assigns a sequence of 0/1 (off/on) currents to each variation in _____ ______ to create binary numbers.

Back 26

analog voltage

Front 27

Raw input from an image intensifier for example is
first converted into a continuously fluctuating
_____ ______ (example: vidicon tube signal)

Back 27

analog signal

Front 28

To convert analog signals into digital form, the computer uses the technique of ________- high speed
readings that are taken at regular intervals

Back 28

sampling

Front 29

The last step in the conversion is to....? Then the input is entirely digital

Back 29

assign a binary
numerical value to each of the readings

Front 30

The CPU is the _____ of every computer.

Back 30

heart

Front 31

What is the function of the CPU?

Back 31

It directs information to and from the various
components that make up the system.

Front 32

Internal components of the CPU include what three things?

Back 32

a control unit,
an arithmetic logic unit (ALU), and registers or
temporary storagedirects step by step
operations of processing

Front 33

The Control unit directs what?

Back 33

directs step by step
operations of processing

Front 34

The arithmetic logic unit is what?

Back 34

The area of the
CPU where adding, subtracting, and
comparing operations are performed

Front 35

What are registers?

Back 35

The registers are a temporary storage location for small amounts of data, or for
intermediate results during processing

Front 36

Electrical connections between CPU and the
components run along a system of parallel or
series conductors called a

Back 36

Bus

Front 37

Describe a bus in Ron's words

Back 37

The bus is like a city bus route, picking up
passengers (data) along the conductor

Front 38

Computers have a clock, that with each “tick”, causes what?

Back 38

An operation to occur

Front 39

These clocks run
at very ____ speeds, (i.e. 2GB/sec). Think of this
as the _____ _____ on the bus.

Back 39

high;
speed limit

Front 40

Information can be stored in a computer’s memory by what two ways?

Back 40

Magnetic variations or
transferred voltage (on or off).

Front 41

Memory is classified as which two ways?

Back 41

read (extracted information) and write (replaces or deletes old memory with new information)

Front 42

RAM stands for what?
What does it do?
It is constantly doing what?
What is Volatile?

Back 42

Random Access memory

Temporary storage for programming

Constantly changing

Volatile- lost when power is removed

Front 43

ROM stands for what?
What does it contain?
What does Nonvolatile stand for?

Back 43

Read Only Memory

Contain basic operating instructions that don’t change

Nonvolatile- not lost when power is removed

Front 44

Peripheral devices permit does what?

Back 44

input and /or
output of information to/from the CPU.

Front 45

What does Peripheral devices Consists of?

Back 45

Memory storage devices

Input devices

Output devices

Front 46

Memory devices include:

Back 46

Magnetic and optical (laser recording and reading) recording on both tape and disk

Optical disks permit significantly more data storage

Large amounts of magnetically stored data require a hard disk

Front 47

Devices that provide input of data to the CPU Include :

Back 47

Keyboard

Mouse

Joystick

Image receptors

TV cameras

Ion chambers

Transducers

RF detectors

Front 48

Human senses (sight/sound) are _____
in nature.

Back 48

analog

Front 49

Output devices provide analog data from the _____ ____manipulated inside the CPU.

Back 49

digital data

Front 50

This is accomplished by running the digital data through a _____ ______ _____ before reaching the output device

Back 50

digital to analog converter (DAC)

Front 51

Output devices include:

Back 51

Speakers

CRT: cathode ray tube screens

LCD: Liquid crystal display screens

Printers (paper)

Laser film printers

Front 52

A digital image is one that has been converted into ...?

Back 52

numerical values for transmission or processing.

Front 53

______ acquire information either by scanning an area for information or by array detection, in which information is received from an entire area at once.

Back 53

Detectors

Front 54

A ______ is a square series of boxes that gives form to the image

Back 54

matrix

Front 55

Each box in the matrix will display a visual _____ _____ equal to a numerical value from the data

Back 55

density level

Front 56

The greater the matrix size, the ______ the
resolution because the pixels are smaller

Back 56

better

Front 57

Each box in the matrix will display a visual density level equal to a numerical value from the data. These boxes are called ...?

Back 57

pixels (picture elements)

Front 58

Each pixel location is determined by its ...?

Back 58

address

Front 59

Each pixel corresponds to a three-dimensional volume of tissue known as a ...?

Back 59

voxel (volume element)

Front 60

What is the definition of bit depth?

Back 60

the number of shades of gray
in each pixel

Front 61

____ _______is determined by the number of bytes used
per pixel

Back 61

Bit depth

Front 62

A gray scale bit depth of 8-16 would require _-_ bytes per pixel

Back 62

1-2

Front 63

What is the definition of DICOM?

Back 63

Definition: a standard for imaging hardware and software- Digital Imaging and Communication in Medicine

Front 64

What does DICOM do?

Back 64

Allows machines of different
manufacturers to communicate (speaks
the same language)

Front 65

The quality of the data acquired from the
image receptor is measured by:

Back 65

Frequency

Contrast

Noise

Front 66

________ _____is the raw data to which a
Fourier transformation is applied.

Back 66

Frequency data

Front 67

A high contrast image has ____ frequency

A low contrast image has ____ frequency

Back 67

High;
Low

Front 68

The ________ _________ is the total amount of contrast within the image.

Back 68

Acquired frequency

Front 69

As with any image contrast, the acquired contrast is a...?

Back 69

Measure of the differences
between the data values.

Front 70

A ______ relationship exists between subject contrast and acquired data contrast.

Back 70

Direct

Front 71

When the subject contrast is high, the
acquired data contrast will be ____?

Back 71

High

Front 72

_____ _____ is random background information. It is detected, but does not
contribute to the image.

Back 72

Image noise

Front 73

Most fluoroscopic noise comes from the image chain- the __ _______ being the noisiest component.

Back 73

TV pickup

Front 74

A clear data stream without noise might look like this on an oscilloscope (A or B)

Back 74

A

Front 75

Noise might look like this on an oscilloscope (A or B)

Back 75

B

Front 76

Noise has an ______
relationship to contrastan
increase in noise decreases image contrast.

Back 76

inverse

Front 77

How is noise measured?

Back 77

Noise is measured as the “signal to noise
ratio”

Front 78

____ is the ratio of the amplitude of the
data (Signal) to that of the noise.

Back 78

SNR

Front 79

Commercial systems have a SNR of approx. ___

High resolution digital fluoroscopy systems
have a SNR between ____ and ____

Back 79

200;

500 and 1000

Front 80

The human visual range can only perceive __ or fewer shades of gray.

Yet the remnant x-ray beam contains over ____ potential gray shades.

Back 80

32;

1000

Front 81

True or false: Many of these photon detectors are sensitive to the majority of these gray shades.

Back 81

True

Front 82

Numerical values determine the density and contrast for each _____

Back 82

Pixel

Front 83

True or false: Because the range of potential densities is much greater than the human visual range, any digital image is only a small part of the total number of densities.

Back 83

True

Front 84

Each image is only a _____ on the total range of data that can be manipulated by the computer!

Back 84

Window

Front 85

To manipulate the density of each pixel, as many as __ bits of data per pixel may be required to determine what shade of gray is selected.

Back 85

12 bits of data per pixel

Front 86

The __________ has the responsibility for selecting the proper density and contrast displayed by the computer.

Back 86

Radiographer

Front 87

The two values that the radiographer controls to create a window of the total number of densities is:

Back 87

Window Level

Window Width

Front 88

True or false: Because a computer can express a vast range of values, it cannot seee image densities far below and beyond the range of human vision.

Back 88

Flase; it can

Front 89

The computer can bring density differences into visual range from extremely ____ input doses that would produce densities below the normal range of vision.

Back 89

Low

Front 90

What controls image density?

Back 90

Window Level

Front 91

The ______ ______ must be adjusted to the proper level to diagnostically relevant information

Back 91

Window level

Front 92

What happens to info on the outside of the level?

Back 92

Information outside
this level is lost

Front 93

________ ______represent the density of each substance in the body

Back 93

Hounsfield units (HU)

Front 94

Bone=?
Water=?
Air=?

Back 94

+1000 = bone

0 = water

-1000 = air

Front 95

_____ window level
demonstrates high HU’s
(+1000): dense objects
like bone

Back 95

High

Front 96

Levels around 0 to +120
demonstrate _____ _______
structures

Back 96

Soft tissue

Front 97

Levels below 0 will
demonstrate low density
structures like _____ ______

Back 97

Lung tissue

Front 98

When the values of each pixel are changed by computer manipulation, the value range of the entire image does what?

Back 98

It changes

Front 99

Can a computer can expand or compress image
densities to fill the entire range of human vision?

Back 99

Yes it can

Front 100

Window width sometimes called _____ _____expansion or compression. (Sounds like contrast to me!)

Back 100

“gray scale”

Front 101

What controls image contrast?

Back 101

Window Width controls
image contrast!

Front 102

There is an ________
relationship between
window width and image
contrast.

Back 102

Inverse

Front 103

As the window widens, more densities will make up the image, thus a ______ scale of contrast results between white and black.

Back 103

Longer

Front 104

An extremely ______ window width requires the computer to ignore large amounts of information.

Back 104

Narrow

Front 105

For this reason, window width is said to also control _____ of _____(as with a radiograph,
the info is there, you just cannot see it).

Back 105

Visibility of detail

Front 106

____ windows cause objectionable increases
in image noise.

Back 106

Narrow windows

Front 107

True or false: The window width must be adjusted to demonstrate the greatest amount of relevant information.

Back 107

True

Front 108

As the text suggests, it is advisable to set the Window ______ first, then determine an appropriate window _____.

Back 108

window level (density) first, then window width (contrast)

Front 109

True or false: with digital radiography, adjusting the window level and width will remove info on the image for the doctor!

Back 109

True

Front 110

What is resolution controled by?

Back 110

Resolution is controlled by matrix size.

Front 111

There is a _____ relationship between matrix
size and image resolution.

Back 111

Direct

Front 112

Matrix size is not variable within a system. It is controlled by the quantity of....

Back 112

Image detectors and the accompanying electronics.

Front 113

The primary limitation on resolution of digital images is the raster scan pattern on the ....

Back 113

CRT

Front 114

A 525 line unit produces about ____ lp/mm.

Back 114

1-2

Front 115

The frequency response of the incoming signal is termed the ______.

Back 115

Bandwidth

Front 116

Bandwidth produces limitations with _______ as well.

Back 116

Resolution

Front 117

Progressive scanning (compared to interlaced) slightly ______ resolution

Back 117

Increases

Front 118

Digital filtering is used to do what?

Back 118

Extract additional information

Front 119

True or false: Filtering accentuates or suppresses
selected frequencies

Back 119

True

Front 120

Digital filtering is classified as what three factors?

Back 120

Low-pass filtering

Band-pass filtering

High-pass filtering

Front 121

Describe low-pass filtering

Back 121

Amplifies or deletes all but the low frequencies

Used to reduce image contrast or high frequency noise

Called smoothing

Front 122

Describe band-pass filtering

Back 122

Amplifies or deletes all but a selected range of frequencies.

Front 123

Decribe High-pass filtering

Back 123

High-pass

Amplifies or deletes all but the high frequencies

Increases image contrast.

Called edge enhancement or sharpening