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Chapter 9
SWGTC-R/T-Chapter 9-Wallace-Grids & the Bucky
Question | Answer |
---|---|
using a grid <increases/decreases> radiographic contrast | increases |
what do grids do to scatter? | grids absorb scatter and prevent scatter from reaching the film |
each strip on a grid is separated by a space called a/an __________. | interspace |
the interspace can be made of : | cardboard fiber, aluminum or plastic |
the interspace material is __________, which means that it does not absorb the x-ray beam. | radiolucent |
most common grid | focused grid |
strips in center are parallel to each other, angled at the sides on this grid | focused grid |
all strips are parallel on this grid | parallel grid |
this grid pattern absorbs the most scattered radiation | crossed/cross-hatch grid |
grid ratio | relationship between the height of the lead strips and the distance between them |
What will absorb more radiation, a high ratio grid (16:1) or a low (6:1)? | High (16:1) |
Grid frequency | number of grid lines per inch |
unwanted absorption of primary radiation by the grid | grid cut-off |
What will cause grid cut-off when using a focused grid? | wrong SID. grid is angled against the grid lines, grid is angled in relation to the x-ray beam, grid is upside down |
focal range | acceptable range of SID's that can be used with a focused grid |