7. Qualities of the radiographic image

Question 1

What is the controlling factor for spatial resolution?

Answer 1

Acquisition pixel size (small pixels that are inside of the IR)

Question 2

What is spatial resolution?

Answer 2

The geometrical sharpness/structural sharpness

Question 3

What are the 5 characteristics of high spatial resolution?

Answer 3

-Demonstrates the difference between two objects that are very close together
-Little or low blur
-Very detailed or high-detail
-Crisp edges
-Structural Sharpness in the image

Question 4

What part of the image is sharper? The anode side or the cathode side?

Answer 4

The anode

Question 5

What are the four things that spatial resolution is affected by?

Answer 5

1. Focal spot size
2. Movement
3. OID
4. SID

Question 6

With a decrease in focal spot size, will there be an increase or a decrease in sharpness?

Answer 6

Increase sharpness

Question 7

With an increase in focal spot size, will there be an increase or a decrease in sharpness?

Answer 7

Decrease sharpness
There is less sharpness with a larger focal spot size because of the increase in focal spot blur. The more focal spot blur, the less sharp or lower spatial resolution that an image has.

Question 8

What is another word for focal spot blurriness?

Answer 8

Penumbra

Question 9

With an increase in SID, will there be an increase or decrease in sharpness?

Answer 9

Increase sharpness

Question 10

Why do we not always use a longer SID?

Answer 10

More wear on the machine due to higher mAs, and its not always practical

Question 11

With a decrease in OID, will there be an increase or decrease in sharpness?

Answer 11

An increase in sharpness

Question 12

What 3 things are size distortion caused by?

Answer 12

Increase in OID, decrease in SID, post processing

Question 13

What has a more dramatic affect on size distortion/magnification? OID or SID?

Answer 13

OID

Question 14

What is shape distortion? What are the 2 types?

Answer 14

“Misrepresentation” of an objects true shape
1. Foreshortening
2. Elongation

Question 15

How does foreshortening happen?

Answer 15

When object is angled, CR remains perpendicular to the IR

Question 16

How does elongation happen?

Answer 16

1. Object is parallel to the IR, CR is angled
2. CR is perp. to the object, IR is angled

Question 17

How do you measure detail/spatial resolution?

Answer 17

Measure the detail with a lp (line pair)/mm test tool

Question 18

In a lpmm test, how do you know that there is an increase in detail?

Answer 18

The greater the amount of line pairs that are visible in a given space, the better the detail

Question 19

What will cause less anode heel effect, an increase or a decrease in SID?

Answer 19

An increase in SID causes LESS anode heel effect

Question 20

Why is there less intensity on the anode side of the image?

Answer 20

The photons that make up the useful beam emitted from the anode side, must traverse a greater distance through the target than on the cathode side

Question 21

Which side should you image thicker anatomy on, the cathode or the anode?

Answer 21

Cathode