Ch. 18 The Grid (Exp I)

Question 1

A grid is used to improve:

Answer 1

Radiographic contrast

Question 2

A grid absorbs:

Answer 2

Scatter radiation

Question 3

When an x-ray beam passes through the body,

Answer 3

• It will pass through the body unaffected
• It will be absorbed by the body
• It will interact with the body and change direction

Question 4

Photons that pass through the body unaffected produce:

Answer 4

Radiographic contrast

Question 5

Photon absorption within the body occurs as the result of:

Answer 5

Photoelectric absorption

Question 6

The atomic interaction that produces scatter radiation is:

Answer 6

Compton

Question 7

As kVp increases,

Answer 7

• Contrast decreases
• Scatter increases
• Image receptor exposure increases

Question 8

The greatest source of scatter during a radiographic examination is the:

Answer 8

Patient

Question 9

The amount of scatter radiation produced increases with:

Answer 9

• An increase in patient thickness
• Larger field size
• Decrease in atomic number of the tissue

Question 10

As a general rule, a radiographic grid is employed:

Answer 10

For part thicknesses above 10 cm

Question 11

The use of a radiographic grid requires:

Answer 11

• Attention to central ray angulation
• An awareness of the SID
• An increase in exposure factors

Question 12

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

Answer 12

b. A grid is a series of lead strips that alternate with radiopaque interspace strips

Question 13

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

Answer 13

Blur out the radiopaque strips

Question 14

The radiopaque strips:

Answer 14

• Absorb scatter
• Are made of dense material
• Have a high atomic number

Question 15

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

Answer 15

ratio

Question 16

Which grid would have the greatest distance between lead strips?

a. 15:1
b. 12:1
c. 8:1
d. 6:1

Answer 16

d. 6:1

Question 17

Which grid would most effectively reduce scatter?

a. 6:1
b. 8:1
c. 12:1
d. 15:1

Answer 17

d. 15:1

Question 18

The number of grid lines per inch is the grid:

Answer 18

Frequency

Question 19

As the lead content of a grid increases,

Answer 19

The ability of the grid to remove scatter increases

Question 20

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

Answer 20

Linear

Question 21

Angulation across the long axis of a linear grid causes:

Answer 21

Grid cut-off

Question 22

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

Answer 22

Convergence

Question 23

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

Answer 23

Potter-Bucky diaphragm

Question 24

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

Answer 24

Perpendicular

Question 25

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

Answer 25

The Moire effect is a consideration.