Deck 5: Scatter Control

Question 1

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) Ask a patient with a large abdomen to lie prone instead of supine.

Answer 1

Increase the grid ratio.

Question 2

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) A and C

Answer 2

The scatter photons are more likely to miss the image receptor.

Question 3

Which of the following beam restricting devices is best at limiting unsharpness surrounding the radiographic image?

A) Collimator
B) Cylinder cone
C) Aperture diaphragm
D) Focused grid

Answer 3

Collimator

Question 4

If an excellent knee radiograph is produced using 10 mAs and an 8:1 ratio grid, how much mAs will be needed if no grid is available?

A) 2.5 mAs
B) 4 mAs
C) 8 mAs
D) 10 mAs

Question 5

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) Ask a patient with a large abdomen to lie prone instead of supine.

Question 6

Which of the following statements is true?

A) If the height of the lead strips 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.

Question 7

What is the result of imaging a thicker part or patient?

A) More Compton interactions
B) Decreased scatter
C) Increased radiographic contrast
D) Decreased fog

Question 8

When a grid is needed but not available, the _____ may be used for certain examinations.

A) Tomographic technique
B) Air-gap technique
C) Seldinger technique
D) Reverse collimation technique

Question 9

The height of the lead strips relative to the distance between the lead strips is the measure of:

A) Contrast improvement
B) Grid ratio
C) Bucky factor
D) Grid selectivity

Question 10

If the height of the grid strip is 16 mm, the distance between the strips is 2 mm, and the strip is 0.3 mm thick, what is the grid ratio?

A) 8:1
B) 10:1
C) 12:1
D) 16:1

Question 11

What occurs when the x-ray beam is not properly aligned with the grid strips?

A) Bucky delamination
B) Grid cutoff
C) Increased exposure to the IR
D) Nothing

Question 12

The number of lead strips per inch in a grid is a measure of:

A) Grid selectivity
B) Grid ratio
C) Grid frequency
D) Contrast improvement number

Question 13

What is the grid conversion factor for a 12:1 ratio grid?

A) 3 $\times$
B) 4 $\times$
C) 5 $\times$
D) 6 $\times$

Question 14

What purpose does positive beam limitation serve?

A) To prevent the technologist from placing an image receptor in the Bucky tray that is too large for the study performed
B) To allow the technologist to use an exposure field larger than the image receptor size
C) To prevent first-year students from having to repeat studies by not aligning the Bucky tray with the image receptor
D) To reduce patient exposure by limiting the exposure field to the same size as the image receptor in the Bucky tray

Question 15

Which beam restriction device can be cut to the size needed?

A) A collimator
B) An aperture diaphragm
C) A cylinder
D) A cone

Question 16

In general, when should a grid be used?

A) When part thickness exceeds 4 cm
B) When kV exceeds 40 kVp
C) When kV exceeds 1.02 MeV
D) When part thickness exceeds 10 cm

Question 17

What type of grid error results in appropriate exposure to the middle of the IR and marked underexposure along the sides of the IR?

A) Stationary grid
B) Upside-down focused grid
C) Lateral decentering
D) Off-level

Question 18

Which grid design is manufactured to match the divergence of the x-ray beam?

A) The parallel grid
B) The crossed grid
C) The reciprocating grid
D) The focused grid

Question 19

Due to 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) Reciprocrating grid

Question 20

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.

Question 21

What is found between the lead strips in a grid?

A) Lead
B) Tungsten
C) Radiopaque material
D) Radiolucent material

Question 22

Decreasing collimation results in:

A) A smaller field size
B) A larger field size
C) Decreased patient dose
D) Less scatter production

Question 23

The recommended SIDs that can be used with a focused grid describes the:

A) Focal distance
B) Convergent point
C) Focal range
D) Convergent line

Question 24

Grids that move during the exposure:

A) Are reciprocating grids
B) Move from top to bottom
C) Are part of the Potter-Bucky diaphragm
D) A and C

Question 25

Decreasing grid ratio (with no change in frequency)results in _____________scatter cleanup and ____________ lead content.

A) Decreased; decreased
B) Decreased; increased
C) Increased; decreased
D) Increased; increased

Question 26

The most common cause of grid cutoff is due to:

A) Using a focused grid upside down
B) Off-center misalignment
C) Off-focus misalignment
D) Off-level misalignment

Question 27

Grid frequencies can range from:

A) 10 to 30 lines per centimeter
B) 25 to 80 lines per centimeter
C) 60 to 120 lines per centimeter
D) 25 to 80 lines per inch

Question 28

A beam restricting device that has 2 or 3 sets of lead shutters is a(n):

A) Collimator
B) Aperture diaphragm
C) Cone
D) Cylinder

Question 29

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-focus
C) Off-center
D) Upside-down focused

Question 30

Grid ratios range from:

A) 2:1 to 6:1
B) 4:1 to 16:1
C) 10:1 to 24:1
D) 20:1 to 32:1

Question 31

An aperture diaphragm with an attached elongated tube is a(n):

A) Collimator
B) Aperture diaphragm
C) Cone
D) Cylinder

Question 32

The purpose of the mirror inside the collimator is to:

A) Allow the patient to see the radiographer
B) Allow the radiographer to see the patient
C) Project a light field onto the patient
D) None of the above

Question 33

Significant collimation requires an increase of _____________ of the mAs.

A) 0%
B) 1 to 5%
C) 10 to 20%
D) 30 to 50%

Question 34

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-focus misalignment
D) Off-level misalignment

Question 35

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) A and C

Question 36

Which of the following beam restricting devices is least effective at limiting unsharpness surrounding the radiographic image?

A) Collimator
B) Cylinder cone
C) Aperture diaphragm
D) Focused grid

Question 37

The unrestricted primary beam produces a(n)_________ area of exposure.

A) Round
B) Oval
C) Square
D) Rectangular

Question 38

Grid ratio can be expressed mathematically as:

A) Thickness of lead strips divided by distance between them
B) Height of lead strips divided by distance between them
C) Height of lead strips divided by thickness of lead strips
D) Length of lead strips divided by distance between them

Question 39

An optimal AP abdomen radiograph can be produced using 40 mAs, 75 kVp, and a 12:1 grid.How much mAs would be needed if the only grid available is a 6:1 ratio grid?

A) 20 mAs
B) 24 mAs
C) 67 mAs
D) 80 mAs

Question 40

When using a digital flat-panel detector:

A) The x-ray beam will automatically collimate to the appropriate size for the part.
B) The entire detector should be exposed.
C) The radiographer must adjust the collimator to the area of interest.
D) A and C

Question 41

The only reason a grid should be used is to increase radiographic contrast.

Question 42

Digital IRs are less sensitive to scatter radiation than are film-screen IRs.

Question 43

The results of the collimator alignment quality control test should demonstrate that the alignment is within 5% of the SID used.

Question 44

As collimation decreases, exposure to the IR increases.

Question 45

Grids do not reduce scatter production.

Question 46

Increasing collimation results in reduced patient exposure, increased field size, and reduced scatter production.

Question 47

An adult's knee measuring 14 cm should be done without a grid.