Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

RT 212 > 5. Digital Radiographic Image Processing and Manipulation > Flashcards

5. Digital Radiographic Image Processing and Manipulation Flashcards

1
Q

The images are processed to mimic the appearance of

A

screen-film images

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

DIGITAL PROCESSING WILL ALSO

ADJUST FOR TECHNICAL ERRORS:

A

• allow for a wider range of subject contrast
• enhance the spatial frequency of certain tissues
or regions of interest
• allow the radiologist to highlight certain areas of
interest, often with special processing functions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

2 STEPS IN IMAGE PROCESSING

A
  1. Preprocessing

2. Postprocessing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Occurs prior to the image being displayed

A

Preprocessing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

algorithms determine the image histogram

A

Preprocessing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

detector defects are removed

A

Preprocessing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

noise corrections are performed

A

Preprocessing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Done by technologist to prepare the image for the

radiologist through various user functions

A

Postprocessing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

May also be performed by radiologist to produce
specialized images to aid the radiologist in a
diagnosis

A

Postprocessing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

is a graph of the number of pixels in the entire
image or part of the image having the same gray levels (density
values), plotted as a function of the gray levels

A

Image Histogram

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

y-axis

A

Number of Pixels or Frequency of occurrence of various gray levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

x-axis

A

Pixel Intensity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

gray value
representing the
strength of the
acquired signal

A

Horizontal Axis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Pixel intensity

A

Horizontal Axis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Number of pixels in

each tone

A

Vertical Axis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

____ of the graph represent black areas (greater acquired signal)

A

One End

Example: Air

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

shade of gray, representing medium tones

A

Middle Area

Example: Soft tissue, muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

represents white (no acquired signal)

A

Extreme Opposite Area

Example: Bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

This graphic representation appears as a pattern of peaks and valleys
that varies for each body part

A

Image Histogram

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

creates a wider histogram

A

Low energy (low kVp)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

long scale of contrast

A

Low energy (low kVp)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

creates a narrow histogram

A

High energy (high kVp)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

short scale of contrast

A

High energy (high kVp)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Analysis of the histogram is very

A

complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
The shape of the histogram is ____ specific
anatomy
26
It is important to choose the correct _____ on the | menu for the body part exposed
anatomic region
27
Digital Radiography Signal Sampling
1. The Nyquist Theorem 2. Aliasing 3. Rescaling 4. Look-up Table
28
described a way to convert analog signals into digital | signal that would more accurately transmit over telephone lines
1928 – Harry Nyquist
29
Sampling
Nyquist Theorem
30
states that when sampling a signal (ADC) the sampling frequency must be greater than twice the frequency of the input signal so that the reconstruction of the original image will be as close to the original signal as possible
Nyquist Theorem
31
``` In digital imaging, at least ____ the number of pixels needed to form the image must be sampled ```
twice
32
If too few pixels are sampled, the result will be a
lack of resolution
33
when the spatial frequency is greater than the Nyquist frequency & the sampling occurs less than twice per cycle, information is lost and a fluctuating signal is produced
Aliasing
34
Undersampling
Aliasing
35
when the (fluctuating) signal is reproduced, frequencies above the Nyquist frequency causes
Aliasing (Foldover or Biasing)
36
causes mirroring | of the signal at ¼ the frequency
Aliasing (Foldover or Biasing)
37
a wraparound image is produced, which appears as two superimposed images that are slightly out of alignment, resulting in a
Moire effect
38
when exposure is greater or less than what is needed to produce an image, it occurs in an effort to display the pixels for the area of interest
Automatic Rescaling
39
means that images are produced with uniform brightness and contrast, regardless of the amount of exposure used to acquire the image
Automatic Rescaling
40
Histogram of the luminance values derived during image | acquisition
Look-up Table
41
Used as a reference to evaluate the raw information & correct the luminance values
Look-up Table
42
This is a mapping function in which all pixels (each with its own specific gray value) are changed to a new gray value
Look-up Table
43
are data stored in the computer that is used to | substitute new values for each pixel during the processing
Look-up Table (LUT)
44
The resultant image will have the appropriate appearance in | brightness and contrast
Look-up Table (LUT)
45
There is a ___ for every | anatomic part
LUT
46
The LUT can be graphed by plotting the original values ranging from ____ on the horizontal axis and the new values (0-255) on the vertical axis
0 to 225
47
displayed as black
< 50
48
displayed as white
> 250
49
displayed as shades of | gray
50-150
50
Quality Control Workstation Functions Image Processing Parameters
1. Contrast Manipulation 2. Spatial Frequency Resolution 3. Spatial Frequency Filtering
51
Spatial Frequency Filtering
1. Edge Enhancement | 2. Smoothing
52
Converting the digital input data to an image with appropriate brightness and contrast using contrast enhancement parameters
Contrast Manipulation
53
No amount of adjustment can take the place of ____ technical factors selection
proper
54
Ability of an imaging system to differentiate between two near-by objects
Spatial Frequency Resolution
55
The detail or sharpness of | an image
Spatial Frequency Resolution
56
A large pixel size will be unable to resolve two near-by structures as compared to a small pixel size
Spatial Frequency Resolution
57
Measured in lp/mm
Spatial Frequency Resolution
58
high-pass filtering
Edge Enhancement
59
``` Occurs when fewer pixels in the neighborhood are included in the signal average ```
Edge Enhancement
60
useful for enhancing large structures such as organs and soft tissue, but it can be noisy
Edge Enhancement
61
low-pass filtering
Smoothing
62
Occurs by averaging each pixel’s frequency with surrounding | pixel values to remove high-frequency noise
Smoothing
63
Useful for viewing small structures such as fine bone tissues
Smoothing
64
Basic Functions of the Processing System Post-Processing Image Manipulation
1. Window Level & Window Width 2. Background Removal or Shuttering 3. Image Stitching 4. Image Annotation 5. Magnification
65
Most common image post-processing parameters are those for _____ and _____
brightness, contrast (Window Width & Level)
66
controls how bright or dark the screen image is.
Window Level
67
controls the ratio of the black and white, or contrast
Window Width
68
The higher the level is, the ____ the image will be, and the wider the window width, the ____ the contrast
darker (higher), | lower (wider)
69
excess light
Veil Glare
70
is used to blacken out the white collimation borders, | effectively eliminating veil glare
Automatic shuttering
71
unexposed borders around the collimation edges allows excess light to enter the eye
Veil Glare
72
causes oversensitization of a chemical within the eye called _____
Veil Glare, | rhodopsin
73
results in temporary white | light blindness
Veil Glare
74
Removing the white unexposed borders results in an overall smaller number of pixels & ____ the amount of information to be stored
reduces
75
refers to the way anatomy is oriented on the imaging plate
Image Orientation
76
The image is displayed exactly as it was read unless the reader is informed differently
Image Orientation
77
When anatomy or the area of interest is too large to fit on one cassette, multiple images can be “_____” together using specialized software programs
stitched (Image Stitching)
78
allows selection of preset terms and/or manual text input & can be particularly useful when such additional information is necessary
Image Annotation
79
a box placed over a small segment of anatomy on the main image shows a magnified version of the underlying anatomy
Magnification
80
Magnification of the entire image
pan navigation
81
Image Management
1. Patient Demographic Input 2. Manual Send 3. Archive Query
82
Proper identification of the patient is even more critical with digital images than with conventional hard copy film/screen images
Patient Demographic Input
83
Patient Demographic Input Includes:
- patient name - health-care facility - patient identification number - date of birth - examination date
84
arise if the patient name is entered differently from visit to visit or examination to examination
Problems
85
This function allows the QC technologist to select one or more local computers to receive images
Manual Send
86
Most QC workstations are set to automatically send a completed image to the appropriate destinations
Manual Send
87
function that allows retrieval of images from the PACS based on date of examination, patient name or number, examination number, pathologic condition or anatomic area
Archive Query

RT 212 (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions