Question | Answer |
are used to control scatter radiation | Grids |
tools to decrease scatter | The grid, lower kVp ,Decreasing the field size, Decreasing the body part thickness |
Grid was developed by | Gustav Bucky in 1913 |
When you use a grid you ______ the dose to the patient which will _______the mAs | increase increase |
The grid only allows x-rays through that are traveling in | straight lines |
Grids clean up | scatter radiation |
Grids consist of carefully fabricated sections of | radiopaque material (grid lines) alternating with sections of radiolucent material (interspace material) |
Grid ratio | height of the grid/width of the interspace material |
Moving grids aka | reciprocating aka oscillating grids |
clean up scatter radiation better | High ratio grids |
GRID FREQUENCY | Usually 60-110 lines per inch |
Grids with high frequency show | less distinct grid lines |
High frequency grids usually will also have | a higher grid ratio |
The grid lines are made of | lead |
The interspace material is made of | aluminum or plastic |
Both the front and back covers of the grid are usually made of | aluminum |
60-80 grid lines per inch will have to be | shaken |
Most grids have an improvement factor of between | 1.5 and 2.5 |
many shades of gray | low contrast |
black and white | high contrast |
CONTRAST IMPROVEMENT FACTOR | K = Radiographic contrast with a grid/ Radiographic contrast without a grid |
the amount of increase in radiographic technique needed because a Bucky is being used | BUCKY FACTOR |
As the Bucky factor increases | the radiographic technique and patient dose increases |
BUCKY FACTOR | = Patient dose with a grid/ Patient dose without a grid |
Parallel grid | all the lead strips are parallel to each other |
developed by Hollis Potter | Moving grid |
more difficult to manufacture than parallel grids but there is no grid cutoff | Focused grid |
this is the type used most | focused grid |
Grid Cut Off | the grid line absorb to much photons because of the distance of the tube it to far or to close and causes cut off on the film |
problems that cause grid cut off | Off level grid, Off center grid, Off focus grid ,Upside down grid |
is due to the grid being backwards and the film is very dark center and light sides | upside down grid |
AIR GAP TECHNIQUE | does not use a grid |
A gap between the body part and the film | AIR GAP TECHNIQUE |
Improves image contrast | Air Gap Technique |
Put grid lines crosswise and lengthwise | Crossed grid |