Ch. 18 The Grid (Exp I) Flashcards
A grid is used to improve:
Radiographic contrast
A grid absorbs:
Scatter radiation
When an x-ray beam passes through the body,
- It will pass through the body unaffected
- It will be absorbed by the body
- It will interact with the body and change direction
Photons that pass through the body unaffected produce:
Radiographic contrast
Photon absorption within the body occurs as the result of:
Photoelectric absorption
The atomic interaction that produces scatter radiation is:
Compton
As kVp increases,
- Contrast decreases
- Scatter increases
- Image receptor exposure increases
The greatest source of scatter during a radiographic examination is the:
Patient
The amount of scatter radiation produced increases with:
- An increase in patient thickness
- Larger field size
- Decrease in atomic number of the tissue
As a general rule, a radiographic grid is employed:
For part thicknesses above 10 cm
The use of a radiographic grid requires:
- Attention to central ray angulation
- An awareness of the SID
- An increase in exposure factors
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
b. A grid is a series of lead strips that alternate with radiopaque interspace strips
The purpose of moving the grid during the radiographic exposure is to:
Blur out the radiopaque strips
The radiopaque strips:
- Absorb scatter
- Are made of dense material
- Have a high atomic number
The ratio of the height of the lead strips to the distance between the lead strips is the grid:
ratio
Which grid would have the greatest distance between lead strips?
a. 15:1
b. 12:1
c. 8:1
d. 6:1
d. 6:1
Which grid would most effectively reduce scatter?
a. 6:1
b. 8:1
c. 12:1
d. 15:1
d. 15:1
The number of grid lines per inch is the grid:
Frequency
As the lead content of a grid increases,
The ability of the grid to remove scatter increases
When the lead strips run in a single direction in a grid, the grid pattern is described as:
Linear
Angulation across the long axis of a linear grid causes:
Grid cut-off
For a grid to be properly focused, the x-ray tube must be located along the ____ line.
Convergence
A device that moves the grid during a radiographic exposure is called a:
Potter-Bucky diaphragm
A Potter-Bucky diaphragm must move the grid in a direction that is ____ to the direction of the grid lines.
Perpendicular
When using a radiographic grid with computed radiography (CR),
The Moire effect is a consideration.
