ch 18 Flashcards
Purpose of a grid
Improve contrast, absorb scatter radiation
A grid does not _____ the production of scatter
decrease
Primary photons
primary xray beam coming from target
Secondary photons
scatter
Primary photons do one of 3 things:
Transmit, absorb, scatter
Transmit color
Black
Absorb color
White
Scatter color
Grey
Differences in ____ & _____ create contrast on the image
Absorption, transmission
Scatter increases with increased
Field size, KVP, and patient thickness
Grids are used for parts over
10 cm
Grid construction is a series of ______ strips that alternate
radiopaque
What is most commonly used for radiopaque material
lead
What is most commonly used for radiolucent material
Plastic fiber and aluminum
Grid ratio=
h/D (height/interspace material)
Higher ratio grids absorb ____ scatter than lower ratio grids
More
Grid frequency is # of _____ per inch/centimeter
Lead Strips
Grid frequency range
60-200 lines per inch
Higher lead content grids will absorb ____ scatter than lower lead content grids.
more
Linear grids run in _____
one direction
Cross, criss cross, or cross hatched grids run in
2 directions perpendicular to each other
Bucky’s original design was ___
crossed
Linear grids are less likely to produce ___
grid lines
Linear grids will produce cutoff along
lateral edges
