Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Physics - Common Equipment > Chapter 9 > Flashcards

Chapter 9 Flashcards

(58 cards)

Start Studying
1
Q

What determines the overall quality of an image?

A

Visibility of anatomic structures and the accuracy of their structural lines (sharpness)

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

Brightness and contrast are used to describe an images:

A

Visibility

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

How is image sharpness acheived?

A

Maximizing spatial resolution and minimizing distortion

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

How is visibility acheived?

A

Properly balancing brightness and contrast

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

What is brightness?

A

The amount of luminance of a display monitor

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

Brightness can easily be adjusted in digtial imaging because the images are formed by:

A

Numerical data

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

How is brightness adjusted in digital imaging?

A

Adjusting technique or adjusting window during post processing

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

Why should a radiographer repeat the image if it is way too dark or too bright?

A

Windowing can correct brightness but it cannot correct over or under penetrated

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

What does a receptor need to properly utilize as much of the remnant beam as possible?

A

Wide dynamic range

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

What should the radiographer evaluate before sending an image to PACS?

A

Proper exposure, not just brightness

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

What is saturation?

A

Receptor is over exposed, resulting in an image that is burnt out and cannot be corrected with windowing

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

What causes an image to look grainy?

A

Receptor is underexposed

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

What are exposure indicators?

A

Numeric values that indicate the amount of radiation exposure received

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

What is image contrast?

A

The exhibited difference in brightness levels within an image

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

What causes an image to have a washed out appearance?

A

Too little contrast

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

What causes an image to have a black and white appearance

A

High contrast

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

When do we want high contrast vs low contrast?

A

High - bony structures
Low - Soft tissue

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

What is radiographic contrast?

A

Combined results of dynamic range, radiation quality, and the characteristics of tissues being imaged

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

What is subject contrast?

A

Refers to the absorption characteristics of the tissues being imaged

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

What tissue characteristics affect contrast?

A

Thickness, density, and effective atomic number

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

How does high radiation quality alter subject contrast?

A

The stronger the beam, the more likely it is to scatter or pass through the body

Less chance of absorption results in fewer brightness differences - lower contrast

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

How does high absorption affect subject contrast?

A

More brightness differences in the image, but can also degrade image quality of IR is not properly exposed

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

Contrast is a complex image attribute, it is more _______ than brightness

A

Subjective

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

What is grayscale?

Study These Flashcards
A

The number of different shades of gray diplayed

25
What is used to describe an imaging systems ability to differentiate between small structures that attenuate radiation similarly?
Contrast Resolution
26
What is high contrast resolution?
Able to differentiate between small, similar structures
27
Benefit of increased pixel depth?
Provides a larger amount of grays = higher contrast resolution
28
How is contrast adjusted once an image is processed?
Adjusting window width
29
What is spatial resolution?
Used to evaluate the accuracy of anatomic structural lines
30
How does pixel size impact spatial resolution?
The larger the pixels, the less spatial resolution
31
Pixel size formula:
FOV/matrix size
32
If displayed FOV is increased for a fixed matrix size, then pixel size is:
Increased
33
If matrix size is increased for a fixed FOV, then pixel size is:
Decreased
34
The relationship between FOV and matrix size is:
Inversely proportional
35
Resolution in digital imaging is limited by pixel size and:
spatial frequency
36
What is spatial frequency?
Unit of line pairs per millimeter (lp/mm)
37
Relationship between objects and spatial frequency?
Smaller objects have greater spatial frequency Larger objects have lower spatial frequency
38
What makes up a line pair?
A line and a space; a white and black line
39
Relationship between spatial frequency and resolution?
Directly proportional - the more line pairs, the greater the resolution
40
What is MTF?
Modulation Transfer Function - measure of an imaging systems ability to display the contrast of anatomic objects in varying size
41
What are the values for MTE?
0 to 1 0 - no difference in brightness 1- maximum difference in brightness
42
What is DQE?
Detective Quantum Efficiency - measurement of how efficiently an image receptor is in converting x-ray exposure it receives into a quality radiographic image
43
What does 100% DQE represent?
IR would be able to convert all of the radiation it receives into an image with zero information lost
44
What is distortion?
The misrepresentation of the anatomic part in imaging
45
What is size distortion?
Refers to the increased size of the anatomic structure
46
What has a strong effect on size distortion?
SID OID
47
Increased OID, results in ______ magnification
Increased
48
Increased SID, results in ________ magnification
Decreased
49
What are the two forms of shape distortion?
Elongation and foreshortening
50
Because digital receptors can detect lower levels of radiation, they are _____ sensitive to scatter
More
51
What is quantum noise (mottle)?
Caused by too little radiation reaching the IR - gives a grainy appearance
52
Method of describing the strength of radiation exposure compared with the amount of noise present in a digital image
Signal-to-noise Ratio (SNR)
53
What is signal?
Amount of radiation exposure captured by the IR
54
What causes noise?
Not enough radiation hits the IR
55
How can noise be decreased?
Increasing signal, however, this also increases patient dose
56
What is the method of describing contrast resoltuion compared with the amont of noise present in an image?
Contrast-to-noise ratio (CTN)
57
How does noise affect CNR and SNR?
Negatively
58
What are artifacts?
Unwanted darkness or brightness level

Physics - Common Equipment (7 decks)

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