Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Slockett's Rad Exposures > Grids > Flashcards

Grids Flashcards

(66 cards)

Start Studying
1
Q

Who built the 1st grid?

A

Dr. Gustav Bucky (1913)

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

What was Dr. Bucky’s original principle?

A

Lead foil strips standing on edge separated by x-ray transparent interspacers

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

What is responsible for dark areas?

A

Transmission

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

What is responsible for light areas?

A

Absorption

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

Who came up with the moving grid?

A

Hollis Potter (1915-1917)

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

What is another name for a moving grid?

A

Wire Grid

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

What was the idea behind the moving/ wire grid?

A

To get rid of grid lines

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

What was the problem with Potters grid?

A
  • It was filtering out radiation before it got to the patient
  • Required high technique to get through the grid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What was the Potter Bucky Diaphragm?

A

Moving grid

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

What determines when to use a grid?

A
  1. When body part thickness exceeds 10cm
    Ex: shoulders, knees
  2. kVp is above 60
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a grid composed of?

A

Alternating strips of radiopaque and radiolucent material

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

What type of material absorbs scatter?

A

Radiopaque

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

What are the reasons lead is used as the typical radiopaque material?

A
  • Inexpensive
  • Shapes easily
  • High atomic #
  • Dense
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What material are the interspaces, radiolucent or radiopaque?

A

Radiolucent

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

Is the interspace material typically thicker or thinner than lead?

A

Thicker

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

What is often used as the interspace material?

A

Aluminum

*Plastic fiber can also be used

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

Why is aluminum often used as the interspace material?

A
  • Durable

- Absorbs low energy scatter

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

Why is aluminum used more frequently than plastic fiber as the interspace material?

A

Aluminum has a higher atomic number

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

What is grid ratio?

A

The ratio between the lead content and the aluminum content

Height of grid strip (h)
_________________

Interspace width (d)

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

If the height of the lead strips stays the same and the distance between them decreases, what is the result of the grid ratio?

A

It increases

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

What is the grid ratio when the lead strips are 3.2mm high and separated by 0.2mm?

A
  1. 2
    - —- = 16:1
  2. 2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

If a grid ratio has an interspace of 0.5mm and lead strips that are 3mm high, what is it’s grid ratio?

A

3

  • – = 6:1
    0. 5
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the grid ratio range?

A

4: 1 - 16:1

* Mammo can go lower

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

Would a high grid ratio clean up more scatter radiation than a low grid ratio?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What would clean up scatter radiation better, a high or low grid ratio?
High
26
What type of grid ratio would improve contrast?
High
27
How does a high grid ratio clean up more scatter radiation?
It has more lead strips
28
What type of relationship exists between the distance between the lead strips and the grid ratio when the height of the grid strips stays the same?
Inverse
29
The higher the ratio the ______ room you have before grid cut off?
Less
30
When angling against a grid, do you have more room to play with on a 16:1 or an 8:1 grid ratio before you get grid cutoff?
8:1
31
How do you determine grid frequency?
By the number of lead strips per inch or cm
32
Do you have to be more accurate on a low or high grid ratio?
High
33
What is the most often seen grid frequency range?
60-110
34
Typically higher frequency grids have ________ lead strips.
Thinner
35
Which one has a higher frequency, a 10 line grid or an 8 line grid?
10 line grid
36
Higher frequency with the same interspace distance reduces what?
The grid effectiveness
37
What are the most common grid ratio's?
8:1- 10:1
38
How much cleanup will a 5:1 grid ratio give?
85%
39
How much cleanup will a 16:1 grid ratio give?
97%
40
The higher the grid ratio the _______ cleanup.
Better
41
What material is the most important in determining grid efficiency?
Lead
42
Lead content is greater in a grid with a...
High grid ratio
43
As lead increases what happens?
Contrast increases and scatter decreases
44
Parallel grids clean up scatter in how many directions?
One
45
What cleans up scatter better, a parallel grid or a crossed grid?
Crossed grid
46
Which grid has more potential for grid cutoff, parallel or cross?
Cross
47
To be most effective, where must the CR be placed on a Crossed grid?
In the center
48
How many directions does a cross grid clean up scatter?
All directions
49
What kind of grid has lead strips that are angled to match the divergence of the beam?
Focused grids
50
What type of grid requires a specific SID to minimize grid cut off or absorption?
Focused grid
51
What type of grids are more difficult to manufacture?
Focused grid
52
What are the (3) things to remember with focused grids?
1. Centering 2. Alignment 3. SID
53
Do grids move during exposure?
Yes In a reciprocating or oscillating pattern
54
What type of grid movement is described as; motor driven back and forth movement (@2cm)?
Reciprocating
55
What type of grid movement is described as; circular movement?
Oscillating (like a pinball)
56
What are the two types of grid movement?
Reciprocating & Oscillating
57
What is the down side of a moving grid?
Creates image blur Creating more OID
58
What is Selectivity or the "K" factor?
The ability to allow primary radiation to reach the image receptor and prevent scatter
59
Grids are designed to absorb scatter radiation, but they sometimes...
Absorb primary radiation
60
Typically "K" factor ranges between...
1.5- 3.5 (1.5- 3.5 times better when grids are used)
61
What does the "K" factor compare?
Contrast of an image with a grid to one without a grid
62
What is the Contrast Improvement Factor?
Contrast w/ grid -------------------- Contrast w/o grid
63
What are factors when selecting a grid?
- Patient dose - Exam - Detail required - Part thickness - Desired technique - Equipment availability
64
As grid ratio increases, radigraphic density decreases; as grid ratio decreases...
radiographic density increases
65
Below 90 kVp, you can use grid ratio's up to...
8:1
66
Above 90 kVp you often use grid ratio's of...
10:1 or higher

Slockett's Rad Exposures (8 decks)

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