Geometric Qualities: Detail & Distortion

Question 1

What are the geometric properties of radiographic quality?

Answer 1

Sharpness

• detail
• distortion

Question 2

What is the term used for sharpness of recorded detail?

Answer 2

Resolution

Question 3

Magnification is related to what type of distortion?

Answer 3

Size distortion

Question 4

Name the 2 types of shape distortion.

Answer 4

Elongation

Foreshortening

Question 5

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

Answer 5

Resolution

Question 6

What is resolution measured in?

Answer 6

Line pairs per mm

Question 7

Sharp area or shadow under an object:

Answer 7

Umbra

Question 8

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

Answer 8

Penumbra

Question 9

First way to improve resolution:

Answer 9

Eliminate or minimize patient motion.

Question 10

Second way to improve resolution:

Answer 10

Minimize OID.

Question 11

Third way to improve resolution:

Answer 11

Increase SID.

Question 12

Fourth way to improve resolution:

Answer 12

Reduce focal spot size.

Question 13

Fifth way to improve resolution:

Answer 13

Use slower film/screen.

Question 14

Patient motion is a controlling factor of:

Answer 14

Recorded detail.

Question 15

SID=

Answer 15

OID + SOD

Question 16

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

Answer 16

Increase.

Question 17

Increasing penumbra increases or decreases recorded detail?

Answer 17

Decreases.

Question 18

Increasing SID increases or decreases penumbra?

Answer 18

Decreases.

Question 19

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

Answer 19

Increase SID.

Question 20

Does a small focal spot increase or decrease penumbra?

Answer 20

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

Question 21

Quantum mottle refers to:

Answer 21

Image noise due to insufficient mAs.

Question 22

Misrepresentation of the size or shape of the structure:

Answer 22

Distortion.

Question 23

What are the two types of distortion?

Answer 23

Size

Shape

Question 24

What is the only size distortion possible in general radiography?

Answer 24

Magnification, which is controlled by OID & SID.

Magnification degrades resolution.

Question 25

As OID increases, does magnification increase or decrease?

Answer 25

Increase.

Question 26

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

Answer 26

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

Question 27

Shape distortion is controlled by:

Answer 27

Beam/Part/IR alignment

Question 28

Shape distortion can be reduced by:

Answer 28

Oblique positions | Central ray angulations

Question 29

Factors that affect resolution:

Answer 29

``` Pt. motion SID OID focal spot size IR ```

Question 30

Most important for a sharp image:

Answer 30

Reduce pt. motion.

Question 31

Ways to reduce distortion:

Answer 31

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