Deck 18: The Grid

Question 1

The number of grid lines per inch is the grid

A)focus.
B)ratio.
C)frequency.
D)speed.

Answer 1

frequency.

Question 2

The use of a radiographic grid requires

A)attention to central ray angulation.
B)an awareness of the SID.
C)an increase in exposure factors.
D)all of the above

Answer 2

all of the above

Question 3

The amount of scatter radiation produced increases with a/an

A)increase in patient thickness.
B)larger field size.
C)decrease in atomic number of the tissue.
D)all of the above

Answer 3

all of the above

Question 4

A grid absorbs

A)light.
B)incident electrons.
C)scatter electrons.
D)scatter radiation.

Question 5

As a general rule, a radiographic grid is employed

A)for procedures below 60 kVp.
B)for part thicknesses above 10 cm.
C)for pediatric studies to improve contrast.
D)in order to improve positioning latitude.

Question 6

Photons that pass through the body unaffected produce

A)scatter radiation.
B)radiographic contrast.
C)secondary radiation.
D)radiographic distortion.

Question 7

Which grid would most effectively reduce scatter?

A)6:1
B)8:1
C)12:1
D)15:1

Question 8

As the lead content of a grid increases,

A)the contrast improvement factor (K) decreases.
B)the ability of the grid to remove scatter increases.
C)the contrast decreases.
D)exposure to the image receptor increases.

Question 9

Which statement about radiographic grids is incorrect?

A)Grids may have grid strips running in perpendicular directions.
B)A grid is a series of lead strips that alternate with radiopaque interspace strips.
C)The radiopaque strips are typically made of thin lead.
D)The interspace strips are usually made of aluminum.

Question 10

When the lead strips run in a single direction in a grid, the grid pattern is described as

A)criss-cross.
B)linear.
C)cross-hatched.
D)unparallel.

Question 11

When an x-ray beam passes through the body,

A)it will pass through the body unaffected.
B)it will be absorbed by the body.
C)it will interact with the body and change direction.
D)all of the above

Question 12

The purpose of moving the grid during the radiographic exposure is to

A)increase radiographic density.
B)remove unwanted contrast.
C)blur out the radiopaque strips.
D)activate the AEC detectors.

Question 13

The greatest source of scatter during a radiographic examination is the

A)patient.
B)tube.
C)image receptor.
D)grid.

Question 14

The ratio of the height of the lead strips to the distance between the lead strips is the grid

A)selectivity.
B)ratio.
C)frequency.
D)speed.

Question 15

Which grid would have the greatest distance between lead strips?

A)15:1
B)12:1
C)8:1
D)6:1

Question 16

The atomic interaction that produces scatter radiation is

A)Bremsstrahlung.
B)photoelectric.
C)Compton.
D)photodisintegration.

Question 17

Photon absorption within the body occurs as the result of

A)Compton interactions.
B)characteristic interactions.
C)photoelectric interactions.
D)Bremsstrahlung interactions.

Question 18

As kVp increases,

A)contrast decreases.
B)scatter increases.
C)image receptor exposure increases.
D)all of the above

Question 19

A grid is used to improve

A)subject density.
B)image receptor exposure.
C)radiographic contrast.
D)distortion.

Question 20

The radiopaque strips

A)absorb scatter.
B)are made of dense material.
C)have a high atomic number.
D)all of the above

Question 21

A satisfactory abdominal radiograph is produced using a 12:1 grid (grid-conversion factor [GCF] = 5.5), 30 mAs, and 85 kVp.A second film is requested using a 16:1 grid (GCF = 6.75).What mAs is needed to produce the second radiograph with comparable radiographic density?

Question 22

A portable radiograph is taken of a thick body part using a 10:1 stationary grid.The image produced demonstrates a contrast factor (K) of 1.7 .A second radiograph is taken with a different grid of unknown specifications, and the K-value is 2.2.What conclusion can you reach regarding the two grids?

Question 23

A Potter-Bucky diaphragm must move the grid in a direction that is ____ to the direction of the grid lines.

A)perpendicular
B)parallel
C)at a 45° angle
D)at a 37° angle

Question 24

If the lead strips are 2.0 mm high and are separated by an interspace of 0.25 mm, what is the grid ratio?

Question 25

If the lead strips are 4.0 mm high and are separated by an interspace of 0.25 mm, what is the grid ratio?

Question 26

What is the frequency of a grid with lead strips that are 33 micrometers thick and interspace material that is 310 micrometers thick?

Question 27

Match the following choices with the correct question as they relate to radiographic grids.

undesirable absorption of clinically useful radiation

A)grid frequency
B)grid ratio
C)contrast improvement factor
D)focussed grid
E)air-gap technique
F)Moire effect
G)grid cut-off
H)convergence point
I)Hollis Potter
J)Gustav Bucky

Question 28

Match the following choices with the correct question as they relate to radiographic grids.

K

A)grid frequency
B)grid ratio
C)contrast improvement factor
D)focussed grid
E)air-gap technique
F)Moire effect
G)grid cut-off
H)convergence point
I)Hollis Potter
J)Gustav Bucky

Question 29

A satisfactory radiograph is produced using 10 mAs at 85 kVp without a grid.A second film is requested using a 16:1 grid with a conversion factor of 6.75.What mAs is needed to produce the second radiograph?

Question 30

Match the following choices with the correct question as they relate to radiographic grids.

invented the moving grid assembly

A)grid frequency
B)grid ratio
C)contrast improvement factor
D)focussed grid
E)air-gap technique
F)Moire effect
G)grid cut-off
H)convergence point
I)Hollis Potter
J)Gustav Bucky

Question 31

For a grid to be properly focused, the x-ray tube must be located along the ____ line.

A)convergence
B)divergence
C)umbra
D)penumbra

Question 32

When using a radiographic grid with computed radiography (CR),

A)the Moire effect is a consideration.
B)higher frequency grids are undesirable.
C)radiographic grids are unnecessary.
D)none of the above

Question 33

Match the following choices with the correct question as they relate to radiographic grids.

commonly ranges from 85-103 lpi

A)grid frequency
B)grid ratio
C)contrast improvement factor
D)focussed grid
E)air-gap technique
F)Moire effect
G)grid cut-off
H)convergence point
I)Hollis Potter
J)Gustav Bucky

Question 34

Match the following choices with the correct question as they relate to radiographic grids.

undesirable, superimposed lines on CR image

A)grid frequency
B)grid ratio
C)contrast improvement factor
D)focussed grid
E)air-gap technique
F)Moire effect
G)grid cut-off
H)convergence point
I)Hollis Potter
J)Gustav Bucky

Question 35

Match the following choices with the correct question as they relate to radiographic grids.

Higher value improves contrast.

A)grid frequency
B)grid ratio
C)contrast improvement factor
D)focussed grid
E)air-gap technique
F)Moire effect
G)grid cut-off
H)convergence point
I)Hollis Potter
J)Gustav Bucky

Question 36

Angulation across the long axis of a linear grid causes

A)grid shadowing.
B)cross-hatched impressions.
C)grid cut-off.
D)grid convergence.

Question 37

A device that moves the grid during a radiographic exposure is called a

A)short-axis grid.
B)stationary grid.
C)Potter-Bucky diaphragm.
D)focussed grid.

Question 38

Match the following choices with the correct question as they relate to radiographic grids.

must be used at a specific SID

A)grid frequency
B)grid ratio
C)contrast improvement factor
D)focussed grid
E)air-gap technique
F)Moire effect
G)grid cut-off
H)convergence point
I)Hollis Potter
J)Gustav Bucky

Question 39

Match the following choices with the correct question as they relate to radiographic grids.

increased OID

A)grid frequency
B)grid ratio
C)contrast improvement factor
D)focussed grid
E)air-gap technique
F)Moire effect
G)grid cut-off
H)convergence point
I)Hollis Potter
J)Gustav Bucky

Question 40

A satisfactory radiograph is produced using 8 mAs at 85 kVp without a grid.A second film is requested using an 8:1 grid with a conversion factor of 4.What mAs is needed to produce the second radiograph?

Question 41

You have discovered two underutilized radiographic grids in your department.Both grids have the same grid ratio, but grid A is noticeably heavier than grid B.What conclusion can you reach regarding these two grids?