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Exposure 18
Grids
| Question | Answer |
|---|---|
| criss-cross grid | two linear grids placed on top of one another so that the lead strips from a criss-cross pattern |
| cross-hatched grid | two linear grids placed on top of one another so that the lead strips form a criss-cross pattern |
| focused grid | a grid created with the central grid strips parallel with the strips becoming more inclined as they mnove away from the central axis; the lines would intersect along a point in space called the line of convergence |
| grid cut-off | the result of the primary beam being angled into the lead strips |
| grid frequency | the number of grid lines per inch or centimeter |
| grid ratio | the ratio of the height of the lead strips to the distance between the strips |
| linear grid | a grid with lead strips running in only one direction |
| parallel grid | a grid created with the lead and interspace strips running parallel to one another; the lines will necver intersect |
| a grid is employed when | body part thickness exceeds 10cm; kVp is above 60 |
| grid ration formula | grid ratio=height/distanceh=lead strip height d=interspace width |
| grid conversion factor (GCF) | GCF=mAs with the grid/mAs without the grid |
| converting from one grid to another formula | new mAs=old mas x GCF new/GCF old |
Created by:
smweckler
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