Deck 6: Scatter Control

Question 1

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

A) More Compton interactions
B) Decreased scatter
C) Increased radiographic contrast
D) A shorter scale of contrast

Answer 1

More Compton interactions

Question 2

Which of the following is true of scattered radiation?

A) It is produced when the x-ray beams interact with the air prior to striking the patient and results in significant image fog.
B) It can be prevented by reducing the exposure field, increasing tissue thickness, and using faster screens.
C) It may result in an increase in image contrast that reduces the unsharpness of the image.
D) It is most easily controlled by using collimation and a grid.

Answer 2

It is most easily controlled by using collimation and a grid.

Question 3

What occurs when scatter radiation strikes the film?

A) Radiographic contrast increases.
B) Radiographic contrast decreases.
C) Recorded detail decreases.
D) Visibility of recorded detail improves.

Answer 3

Radiographic contrast decreases.

Question 4

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

A) Variable aperture collimator
B) Cylinder cone
C) Aperture diaphragm
D) Focused grid

Question 5

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 6

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

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

Question 7

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 8

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 9

Which of the following statements is true?

A) A high ratio grid prevents the creation 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 10

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 11

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 12

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 13

If the height of the grid strip is 16 mm, the distance between the strips is 2 mm, and the strip is 3 mm wide, what is the grid ratio?

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

Question 14

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.

Question 15

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

A) Bucky delamination
B) Grid cutoff
C) Increased density
D) Nothing

Question 16

A radiograph that has a fogged appearance has most likely been exposed to which of the following?

A) Scatter radiation
B) Primary radiation
C) Coherent radiation
D) Photoelectric radiation

Question 17

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 18

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

A) 3 ´
B) 4 ´
C) 5 ´
D) 6 ´

Question 19

What would be the most difficult grid to use?

A) Focused linear grid
B) Parallel linear grid
C) Cross-hatched grid
D) Low ratio parallel linear grid

Question 20

The amount of mAs required with a grid divided by the amount of mAs needed without a grid is the calculation that determines the:

A) I and II
B) II and III
C) III and IV
D) II, III, and IV

Question 21

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 22

Changing from an 8:1 grid to a 12:1 grid, along with making the appropriate adjustments, will result in:

A) I and III
B) II and III
C) I and IV

Question 23

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 24

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

Question 25

What type of grid error is seen as a loss of density at the periphery of the image?

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

Question 26

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 27

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 28

If a digital image is produced at 40" SID using a focused grid (focal range 66-76"), the image will appear:

A) dark.
B) light.
C) very gray.
D) mottled.

Question 29

What type of grid error is seen as acceptable density in the middle of the film and with decreasing density bilaterally as you move away from the center?

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

Question 30

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