Scatter Control
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1. The projected shape of the unrestricted primary beam is _______________.
a) Square
b) Rectangular
c) Circular
d) Elliptical
Ans:
C
2. A purpose of beam-restricting devices is to _______________ by changing the size and shape of the primary beam.
a) Increase patient dose
b) Decrease scatter radiation produced
c) Increase exposure to the image receptor
d) Decrease image contrast
Ans:
B
3. The most effective type of beam-restricting device is the _______________.
a) Cone
b) Aperture diaphragm
c) Cylinder
d) Collimator
Ans:
D
4. Of the beam-restricting devices listed in question 3, which two are most similar to one another?
a) A and B
b) A and C
c) B and C
d) B and D
Ans:
B
5. The purpose of automatic collimation is to ensure that _______________.
a) The quantity of scatter production is minimal
b) The field size does not exceed the image receptor size
c) Maximal spatial resolution and contrast are achieved
d) Exposure to the image receptor is maintained
Ans: B
6. When making a significant increase in collimation, _______________.
a) mAs should be increased
b) kVp should be increased
c) mAs should be decreased
d) kVp should be decreased
Ans:
A
7. Which one of the following increases as collimation increases?
a) Patient exposure
b) Scatter production
c) Fog
d) Contrast
Ans:
D
8. Which of the following statements is true for positive beam-limiting devices?
a) They are required on all radiographic installations.
b) They are required on all new radiographic installations.
c) They have never been required on radiographic installations.
d) They were once required on new radiographic installations.
Ans:
D
9. The purpose of a grid in radiography is to _______________.
a) Increase exposure to the image receptor
b) Increase image contrast
c) Decrease patient dose
d) Increase spatial resolution
Ans:
B
10. Grid ratio is defined as the ratio of the _______________.
a) Height of the lead strips to the distance between them
b) Width of the lead strips to their height
c) Number of lead strips to their width
d) Width of the lead strips to the width of the interspace material
Ans:
A
11. Compared with parallel grids, focused grids _______________.
a) Have a greater grid frequency and lead content
b) Can be used with either side facing the tube
c) Have a wider range of grid ratios and frequencies
d) Allow more transmitted photons to reach the image receptor
Ans:
D
12. With which one of the following grids would a convergent line be formed if imaginary lines from its grid lines were drawn in space above it? A.
a) Linear focused
b) Crossed focused
c) Linear parallel
d) Crossed parallel
Ans:
A
13. If 15 mAs are used to produce a particular level of exposure to the image receptor without a grid, what value of mAs would be needed to produce that same level of exposure using a 16:1 grid?
a) 45
b) 60
c) 90
d) 105
Ans:
C
14. With exposure technique compensation, which of the following would result in the greatest radiation exposure to the patient?
a) 14 × 17 x-ray field size
b) Air gap technique
c) Cylinder beam restrictor
d) 12:1 grid ratio
Ans:
D
15. Off-focus grid cut-off occurs by using a SID that is not ___________.
a) Within the focal range of the grid
b) Equal to the focal distance of the grid
c) At the level of the convergent line of the grid
d) At the level of the convergent point of the grid
Ans:
A
16. The type of motion most often used for moving grids today is ________.
a) Longitudinal
b) Reciprocating
c) Circular
d) Single stroke
Ans:
B
17. A grid should be used whenever the anatomic part size exceeds _____.
a) 3 cm
b) 6 cm
c) 10 cm
d) 12 cm
Ans:
C
18. The air gap technique uses an increased ________ instead of a grid.
a) kVp
b) mAs
c) SID
d) OID
Ans:
D