Chapter 14 - Grids

Question 1

What is the main reason to use a grid?

Answer 1

to clean up scatter radiation

Question 2

what is the best equipment for reducing the amount of scatter that reaches the film

Answer 2

grids

Question 3

when was the first grid made?

Answer 3

1913

Question 4

Which type of grids are more effective, higher ratio or lower ratio?

Answer 4

higher ratio

Question 5

What is the formula for grid change?

Answer 5

    old grid factor

Question 6

What is the formula for grid ratio?

Answer 6

GR = h/D

h- height of grid strips
D- thickness of interspace

Question 7

What effect does higher ratio grids have on patient dose?

Answer 7

higher ratio grids = higher patient dose

Question 8

What is the number of grid lines per inch or centimeter?

Answer 8

grid frequency

Question 9

What is the purpose of interspace material?

Answer 9

to maintain the separation between lead strips

Question 10

What are the lines imaged when primary x-rays are absorbed in the grid strips?

Answer 10

grid lines

Question 11

What are the 4 grid types?

Answer 11

parallel
crossed
focused
moving

Question 12

What is the simplest type of grid?

Answer 12

parallel grids

Question 13

What is the original type of grids? This grid also has lead strips running parallel to both the long and short axis of the grid

Answer 13

crossed grid

Question 14

Which type of grid is designed to minimize grid cut-off and has grid strips that are angled?

Answer 14

focused grid

Question 15

Which grid moves while the x-ray exposure is being taken and helps prevent grid lines?

Answer 15

moving grid

Question 16

What are the 2 basic types of moving grids?

Answer 16

reciprocating & oscillating

Question 17

What is the most frequent error with grids?

Answer 17

improper positioning

Question 18

What is the undesired absorption of the primary beam?

Answer 18

grid cut-off

Question 19

4 types of grid cut-off

Answer 19

off level
off center
off focus
upside down

Question 20

Off level grid occurs when:

Answer 20

tube or grid is angled

Question 21

off center grid is caused by:

Answer 21

lateral shifting of the beam

Question 22

Off focus grid occurs when:

Answer 22

focused grid is not used at proper SID

Question 23

Your grid selection depends on what 3 factors?

Answer 23

kVp
patient dose
patient size

Question 24

as grids are added or grid ratio increases, contrast _______

Answer 24

increases

Question 25

as grids are added or grid ration increases, density _______

Answer 25

decreases

Question 26

as grids are added or grid ratio increases, patient dose _______

Answer 26

increases