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- Explain
how scatter affects image contrast.
- Explain
the general relationship between x-ray beam area
and image contrast.
- Explain
and illustrate the concept of grid ratio.
What are typical values?
- Distinguish
between parallel and focused
grids.
- Define
the following grid quantities:
a.
primary penetration
b.
Bucky
factor (B)
c.
contrast
improvement factor (K)
- Briefly
explain the following three types of grid cutoff
and describe their effect on images.
a.
incorrect
distance between grid and tube.
b.
off-center grid
c.
tilted
grid
- Discuss
the relationship of contrast improvement to grid
ratio.
- Discuss
the relationship of patient exposure to grid
ratio.
- Describe
the advantages and disadvantages of a low-ratio
grid.
- Describe
the advantages and disadvantages of a high-ratio
grid.
- Discuss
the use of grids in mammography.
- Describe
the differences among the following beam-limiting
devices and the advantages and disadvantages of each.
a.
fixed
cones
b.
light localizing collimators
c.
positive beam limitation (automatic collimators)
- Describe
how grid lines can be eliminated from an image.
- Describe
an air-gap technique.
What are the advantages and disadvantages? Identify a clinical
procedure where it is routinely used.
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