L5

Question 1

• Traditionally, radiographic images were formed in an

Answer 1

analog fashion

Question 2

, containing fluorescent screens and film sensitive to the light
Produced by the screens, is exposed to radiation and then processed in
Chemical solutions.

Answer 2

A
Cassette

Question 3

In an analog system such as film/screen radiography, x-
Ray energy is converted to ____, and the light waves are recorded just as they
Are.

Answer 3

light

Question 4

In digital radiography, analog signals are converted into

Answer 4

numbers that are
Recorded

Question 5

are formed through multiple samplings of the signal
Rather than the one single exposure of an analog image.

Answer 5

Digital images

Question 6

A digital image begins as an

Answer 6

analog signal.

Question 7

Through ____, the image becomes digitized and is sampled multiple times.

Answer 7

computer data
Processing

Question 8

can be described with respect to several characteristics
Or fundamental parameters, including the matrix, pixels, voxels, and the bit dep

Answer 8

A digital image

Question 9

• A digital image is made up of a two-dimensional array of numbers called a

Answer 9

Matrix

Question 10

The matrix consists of ___&____that define pixels.

Answer 10

columns (M) and rows (N)

Question 11

The dimensions of the image are described by

Answer 11

M (columns) and N (rows).

Question 12

• When M=N, the image is_____ ; typically, diagnostic images are

Answer 12

square
rectangular.

Question 13

The _____ (or FOV) is selected during imaging.

Answer 13

matrix size

Question 14

require more processing time and storage space.

Answer 14

Larger images

Question 15

also take longer to transmit to remote locations.

Answer 15

Larger images

Question 16

is necessary to facilitate efficient storage and Transmission

Answer 16

Image compression

Question 17

, or picture element, is the smallest element in a digital Image. If you have ever Magnified a digital picture to the point that you see the image as small squares of Color, you have seen pixels.

Answer 17

A pixel

Question 18

A pixel represents the _______ element in an image.
• It has dimensions given along two axes in millimeters, dictating in-plane spatial
resolution.

Answer 18

smallest sampled 2D

Question 19

• The pixels that make up the matrix are

Answer 19

generally square.

Question 20

Each pixel contains a _____ number representing a

Answer 20

discrete
brightness level.

Question 21

• In radiography and CT, the numbers relate to the ___&____

Answer 21

atomic number and
mass density of tissues.

Question 22

In MRI, the numbers represent other tissue characteristics like _____&___

Answer 22

proton
density and relaxation times.

Question 23

A typical digital chest x-ray might contain ___ columns of pixels and
_____rows of pixels for a total of __ million pixels.

Answer 23

2000
2500
5

Question 24

• Each pixel contains a series of ____&____ defining the grayscale or shade
of that particular point on a digital x-ray image.

Answer 24

1s and 0s

Question 25

• Each space available or a 1 or 0 is called a ___. A group of 8 bits is called a ___

Answer 25

bit byte.

Question 26

• Each pixel is coded with ____ to show different shades, helping to create the detailed digital image you see

Answer 26

numbers

Question 27

• The pixel size can be calculated using the relationship:

Answer 27

Pixel size = FOV/matrix size

Question 28

• For digital imaging modalities, the larger the ___, the smaller the _____ (for the same FOV) and the better the ____

Answer 28

matrix size pixel size spatial resolution.

Question 29

• The _____ is the number of bits per pixel. An image that is described as having a bit depth of 8 will have ____ shades of gray.

Answer 29

bit depth 256 (28)

Question 30

• The term field of view, or FOV, is synonymous with the _____. In other words, it is the amount of body part or patient included in the image.

Answer 30

x-ray field.

Question 31

The larger the FOV, the more area is

Answer 31

imaged.

Question 32

• Changes in the FOV will not affect the size of the matrix; however, changes in the matrix will affect ____. This is because as the matrix increases (e.g., from 512 × 512 to 1024 × 1024) and the FOV remains the same size, the pixel size must decrease to fit into the matrix

Answer 32

pixel size.

Question 33

• The characteristics of a digital image can affect the appearance of the digital image, particularly its ____&___

Answer 33

spatial resolution and its density resolution.

Question 34

refers to the ability of an imaging modality to differentiate two adjacent structures as being distinct from one another.

Answer 34

• Spatial resolution

Question 35

refers to the ability of an imaging system to distinguish between different levels of radiographic density or optical density (OD)

Answer 35

• Density resolution

Question 36

has an effect on the detail or spatial resolution of the image. • The larger the ____ (for the same FOV), the smaller pixel size, hence the better the appearance of detail.

Answer 36

• The matrix size matrix size

Question 37

• Additionally, as the ___ decreases, without a change in matrix size, the size of the pixel decreases as well, thus improving detail.

Answer 37

FOV

Question 38

selects a larger matrix size when imaging larger body parts, such as a chest, in order to show small details in the anatomy.

Answer 38

• The operator

Question 39

has an effect on the number of shades of gray, hence the density resolution of the image.

Answer 39

The bit depth

Question 40

1. In____ , the image is first divided into an array of small square regions called

Answer 40

scanning pixels.

Question 41

2. The second step, _____, simply involves measuring the brightness level of each of the pixels using special devices such as a photomultiplier tube (PMT).

Answer 41

sampling

Question 42

The signal from the PMT is an _____ (voltage waveform) that must be converted into a digital image for processing by a digital computer.

Answer 42

analog signal

Question 43

. The third step in digitizing an image is ____. This is a process whereby the brightness levels obtained from sampling are assigned an integer (zero, a negative, or a positive number) called a ____.

Answer 43

quantization gray level

Question 44

The image is now made up of a range of gray levels. The total number of gray levels is called the

Answer 44

gray scale.

Question 45

plays an important role in the process of converting an analog signal into digital data for input into a digital computer. The ADC consists of several components that will divide up the analog signal into equal parts.

Answer 45

• The Analog-Digital Converter (ADC

Question 46

• Digital imaging modalities have ____ ADCs. The greater the bits, the more accurately the signals from the detectors can be digitized for a faithful reproduction of the original signal. This means that image quality is better with higher bit ADCs compared to lower bit ADCs.

Answer 46

12- to 32-bit

Question 47

Deals with the development of problem specific approaches to enhance the raw medical data for the purpose of selective visualization as well as further analysis.

Answer 47

Basic Image Processing

Question 48

Concentrates on the development of techniques to supplement the usually qualitative and frequently subjective assessment of medical image by human experts.

Answer 48

Basic Image Analysis

Question 49

Plays an important role in assessing any new hardware, software, image acquisition techniques, image reconstruction or post- processing algorithms.

Answer 49

Quality Evaluation

Question 50

Statistics of medical imaging fills the gap and provides a theoretical framework for statistical investigation into medical imaging technologies.

Answer 50

Statistical Analysis and Entropy

Question 51

in digital images is used form any practical purpose, mainly in security fields and also with gray scale images applications.

Answer 51

Color information

Question 52

The system is said to be stable only when the output is bounded for ____. For a bounded input, if the output is unbounded in the system then it is said to be ____.

Answer 52

bounded input Unstable

Question 53

A ___ system satisfies the BIBO means finite in amplitude. Stable and Unstable Signal Processing

Answer 53

stable

Question 54

BIBO stands for

Answer 54

Bounded input for Bounded Output

Question 55

An ____ can be applied to an image to convert it from one domain to another. Viewing an image in domains such as frequency or hough space enables the identification of features that may not be easily detected in the spatial domain.

Answer 55

image transformation

Question 56

Common Image Transforms include:

Answer 56

• Hough Transform • Radon Transform • Discrete Cosine Transform • Discrete Fourier Transform • Wavelet Transform

Question 57

A principal advantage of digital radiographic imaging over screen-film radiographic imaging is the ability to _____ the image before and after display - preprocessing and postprocessing, respectively.

Answer 57

manipulate

Question 58

Pre and Post image processing alter image appearance, usually for the purpose of improving

Answer 58

image contrast.

Question 59

Preprocessing of digital images is largely

Answer 59

automatic.

Question 60

is designed to produce artifact-free digital images.

Answer 60

Preprocessing

Question 61

describes the manipulation of radiographic images to derive additional qualitative or quantitative data.

Answer 61

Advanced post-processing

Question 62

is a key element of information technology platforms in a modern radiology department.

Answer 62

The adequate and repeatable performance of the image display system