Geometric Qualities: Detail & Distortion Flashcards Preview

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Flashcards in Geometric Qualities: Detail & Distortion Deck (31)
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1
Q

What are the geometric properties of radiographic quality?

A

Sharpness

  • detail
  • distortion
2
Q

What is the term used for sharpness of recorded detail?

A

Resolution

3
Q

Magnification is related to what type of distortion?

A

Size distortion

4
Q

Name the 2 types of shape distortion.

A

Elongation

Foreshortening

5
Q

The ability to image two separate objects and visually distinguish them from one another:

A

Resolution

6
Q

What is resolution measured in?

A

Line pairs per mm

7
Q

Sharp area or shadow under an object:

A

Umbra

8
Q

Unsharp shadow surrounding the umbra; width of unsharpness; edge gradient:

A

Penumbra

9
Q

First way to improve resolution:

A

Eliminate or minimize patient motion.

10
Q

Second way to improve resolution:

A

Minimize OID.

11
Q

Third way to improve resolution:

A

Increase SID.

12
Q

Fourth way to improve resolution:

A

Reduce focal spot size.

13
Q

Fifth way to improve resolution:

A

Use slower film/screen.

14
Q

Patient motion is a controlling factor of:

A

Recorded detail.

15
Q

SID=

A

OID + SOD

16
Q

An increase in OID results in an increase or decrease in penumbra?

A

Increase.

17
Q

Increasing penumbra increases or decreases recorded detail?

A

Decreases.

18
Q

Increasing SID increases or decreases penumbra?

A

Decreases.

19
Q

When a minimal OID cannot be achieved, what can be done to compensate?

A

Increase SID.

20
Q

Does a small focal spot increase or decrease penumbra?

A

Decrease.
There is a decreased area over which X-rays are produced.
Small focal spot is used for sharp detail.
Decreased heat dissipation.

21
Q

Quantum mottle refers to:

A

Image noise due to insufficient mAs.

22
Q

Misrepresentation of the size or shape of the structure:

A

Distortion.

23
Q

What are the two types of distortion?

A

Size

Shape

24
Q

What is the only size distortion possible in general radiography?

A

Magnification, which is controlled by OID & SID.

Magnification degrades resolution.

25
Q

As OID increases, does magnification increase or decrease?

A

Increase.

26
Q

Does the X-ray beam diverge more with a shorter or longer SID?

A

Shorter SID.

Longer SID utilizes the central, more perpendicular portion of the beam.

27
Q

Shape distortion is controlled by:

A

Beam/Part/IR alignment

28
Q

Shape distortion can be reduced by:

A

Oblique positions

Central ray angulations

29
Q

Factors that affect resolution:

A
Pt. motion
SID
OID
focal spot size
IR
30
Q

Most important for a sharp image:

A

Reduce pt. motion.

31
Q

Ways to reduce distortion:

A
Increase SID
Reduce OID
Align tube & IR
Part parallel to IR
Part perpendicular to CR
CR through anatomy of interest