Ch. 7 Scatter Production Flashcards
which of the following are tools that the radiographer can use to limit scatter radiation?
a. beam-restricting devices and radiographic grids
b. beam-restricting devices and digital imaging plate
c. radiographic grids and digital imaging plate
d. all options are correct
A
A larger x-ray beam field size results in:
a. increase in scatter produced and increase in fog
b. increase in scatter produced and increase in contrast
c. increase in fog and increase in contrast
d. all options are correct
A
What purpose does positive beam limitation serve?
to reduce patient exposure by limiting the exposure field to the same size as the image receptor in the bucky tray
The unrestricted primary beam produces a(n) _____ area of exposure
Round
Decreasing collimation results in:
A larger field size
As beam restriction increases, field size and patient dose _____
Decreases
As beam restriction increases:
a. less scatter is produced and less volume of tissue is irradiated
b. less scatter is produced and higher image contrast
c. less volume of tissue is irradiated and higher image contrast
d. all options are correct
d. all options are correct
Which beam restriction device can be cut to the size needed?
An aperture diaphgram
Which beam-restriction device is least effective at limiting unsharpness surrounding the radiographic image?
Aperture diaphgram
An aperture diaphragm with an attached elongated tube is a(n):
Cylinder
A beam-restricting device that has two or three sets of lead shutters is a(n)
Collimator
The purpose of the mirror inside the collimator is to:
Project a light field onto the patient
Which of the following will limit the volume of tissue irradiated:
a. cone and collimator
b. cone and electronic masking
c. collimator and electronic masking
d. all options are correct
a. Cone and Collimator
A device consisting of very thin lead strips with radiolucent interspaces intended to absorb scatter radiation emitted from the patient is a:
Grid
Which of the following is NOT a way to reduce the production of scatter radiation
a. reduce the exposure field size
b. reduce the tissue thickness
c. increase the grid ratio
d. increase collimation
c. increase the grid ratio
Which of the following influences the amount of scatter radiation striking the image receptor but NOT the production of scatter radiation
a. reduce the exposure field size
b. reduce the tissue thickness
c. increase the grid ratio
d. electronic masking
The height of the lead strips relative to the distance between the lead strips is the measure of:
Grid ratio
Which of the following statements is true?
a. if the height of the lead strip increases and the space between the grid strips decreases, the grid will be more effective at scatter removal
b. if the height of the lead strip decreases and the space between the grid strips increases, the grid will be more effective at removing scatter radiation
c. a high ratio grid removes little scatter
d. a grid decreases scatter production
a. if the height of the lead strip increases and the space between the grid strips decreases, the grid will be more effective at scatter removal
The number of lead strips per inch in a grid is a measure of:
Grid frequency
Due to the increased potential grid cutoff, which would be the most challenging grid to use?
a. focused linear grid
b. parallel linear grid
c. cross-hatched grid
d. reciprocating grid
c. cross-hatched grid
What is the result of imaging a thicker part of patient?
More Compton interactions
If the height of the grid strip is 16mm, the distance between the strips is 2mm, and the strip is 0.3mm thick, what is the grid ratio?
a. 8:1
b. 10:1
c. 12:1
d. 16:1
8:1
Which of the following statements is true?
a. a high ratio grid prevents the production of scatter better than a low ratio grid
b. a low ratio grid is more effective at removing scatter than a high ratio grid
c. as grid ratio increases, the removal of scatter increases
d. high ratio grids are less effective at removing scatter than low-ratio grids
c. as grid ratio increases, the removal of scatter increases
The amount of mAs required with a grid, divided by the amount of mAs needed without a grid, is the calculation that determines the:
Grid Conversion and Bucky Factor
Which grid design is manufactured to match the divergence of the x-ray beam?
The Focused Grid
What is the grid conversion factor for a 12:1 ratio grid?
5 x
What occurs when the x-ray beam is not properly aligned with the grid strips?
Grid cutoff
In general, when should a grid be used?
When part thickness exceeds 10 cm
When a grid is needed but not available, the _____ may be used for certain examinations.
air-gap technique
What type of grid error results in appropriate exposure to the middle of the IR and marks underexposure along the sides of the IR?
Upside-down focused grid
What is found between the lead trips in a grid?
Radiolucent Material
Also called lateral decentering, the ____ grid error results when the central ray is not aligned to the middle of a focused grid.
a. off-level
b. off-focused
c. off-center
d. upside-down focused
Off-center
Changing from a 8:1 grid to a 12:1 grid, along with making the appropriate adjustments, will result
a. increased patient dose and an image with increased contrast
b. increased patient dose and using more mAs
c. an image with increased contrast and using more mAs
d. all options are correct
all options are correct
Grid frequencies can range from:
a. 10 to 30 lines per cm
b. 25 to 80 lines per cm
c. 60 to 120 lines per cm
d. 25 to 80 lines per inch
25 to 80 lines per centimeter
Grid ratios range from:
5:1 to 16:1
Decreasing the grid ratio (with no change in frequency) results in:
a. decreased lead content and increased contrast
b. decreased lead content and decreased scatter cleanup
c. increased contrast and decreased scatter cleanup
d. all options are correct
b. decreased lead content and decreased scatter cleanup
The recommended SIDs that can be used with a focused grid describe the:
a. focal distance
b. convergent point
c. focal range
d. convergent line
focal range
Grids that move during the exposure:
a. are reciprocating grids and move from top to bottom
b. are reciprocating grids and are part of the potter-bucky diaphragm
c. move from top to bottom and are part of the potter-bucky diaphragm
d. all options are correct
Are reciprocating grids and are part of the potter-bucky diaphragm
a grid whose lead strips run perpendicular to the long axis of the grid is called a(n)
short dimension grid
The most common cause of grid cutoff is due to:
off-level misalignment
The only type of grid cutoff that occurs with both focused and parallel grids is due to:
a. using a focused grid upside down
b. off-center misalignment
c. off-focused misalignment
d. off-level misalignment
d. off-level misalignment
The smaller the volume of tissue irradiated, the:
a. greater the amount of scatter produced
b. less the amount of scatter produced
c. greater the need to use a grid
d. higher the kVp needed
b. less the amount of scatter produced
Why does the air-gap technique work?
a. the scatter photons increase in energy as a result of the distance to the image receptor
b. the scatter photons are more likely to miss the image receptor
c. less scatter is produced
d. more exit radiation reaches the image receptor
b. the scatter photons are more likely to miss the image receptor
T or F
Digital IRs are NOT sensitive to scatter radiation
False
Which of the follow beam-restricting devices is best at limiting unsharpness surrounding the radiographic image
a. collimator
b. cylinder cone
c. aperture diaphragm
d. focused grid
Collimator
