Distortion-Magnification

Question 1

What is magnification?

Answer 1

The difference between the size of the real object and the size of the projected image

Question 2

What is magnification a type of?

Answer 2

Distortion that changes the size of the object

Question 3

At what level should magnification be kept in an image?

Answer 3

At a minimum

Question 4

Why is important to keep magnification to a minimum?

Answer 4

To make sure the physician sees the object as close to its true size

Question 5

What is shape distortion?

Answer 5

The difference between the shape of the real object and shape of the projected image

Question 6

What are the two forms of shape distortion?

Answer 6

Foreshortening and Elongation

Question 7

What is Foreshortening?

Answer 7

When the object gets compressed in the image

Question 8

How does Foreshortening occur?

Answer 8

When the object is not parallel to the IR or the IR is tilted

Question 9

What is Elongation?

Answer 9

When one portion of the object gets stretched out in the image

Question 10

What causes elongation?

Answer 10

The angle of the tube

Question 11

Which of the two shape distortions can be fixed?

Answer 11

Elongation

Question 12

How is shape distortion expressed in terms of length/width?

Answer 12

When the length or the width is changed by elongation/foreshortening, not both changed

Question 13

If all parts of an image is changed uniformly, what type of distortion does that represent?

Answer 13

Magnification

Question 14

In a magnified image, how are length and width different from the original image?

Answer 14

They are both measured larger

Question 15

On radiographs of bones, why is there always some inherent magnification?

Answer 15

Because of the soft tissue

Question 16

What is the magnification formula?

Answer 16

Image Size/object size = SID/SOD

Question 17

What is the SOD formula?

Answer 17

SOD=SID-OID

Question 18

What does the magnification formula calculate?

Answer 18

The projected size of an image

Question 19

What is magnification affected by?

Answer 19

SID, OID and to an extent SOD

Question 20

What happens to magnification when the SID is lower?

Answer 20

Magnification increases

Question 21

What happens to spatial resolution when magnification increases?

Answer 21

It becomes worse

Question 22

What positive role does magnification play in imaging?

Answer 22

It can help identify smaller details that otherwise wouldn’t be visible on an actual sized object

Question 23

Which type of x-ray produces the most Foreshortening?

Answer 23

Portable x-rays

Question 24

How can you counteract unwanted OID?

Answer 24

By increasing SID

Question 25

How does SID relate to magnification?

Answer 25

As SID is decreased, magnification increases

Question 26

How is magnification related to sharpness?

Answer 26

As magnification is decreased, sharpness increases

Question 27

How does SID relate to sharpness?

Answer 27

As SID increases, sharpness increases

Question 28

When does mottle show more?

Answer 28

When an image is magnified which is why its important to look at exposure indicator

Question 29

What is another way shape distortion can be achieved on an image?

Answer 29

By off-centering the beam

Question 30

How does angling the part distort the image?

Answer 30

Causes foreshortening

Question 31

What effects do these distances have on the image?

Answer 31

Effect image distortion and spatial resolution

Question 32

What general rule can be stated for SID in practice to keep magnification under control?

Answer 32

Increasing the SID will produce less magnification

Question 33

What image quality are magnification and distortion part of?

Answer 33

Recognizability/Geometric integrity