Two factors affecting amount of scatter reaching IR:
A. kVp=controls __1__ - Increased kVp»_space; Increased __2__
B. Volume of tissue - Increased tissue thickness»_space; Increased __3__.
- Scatter
- Scatter
- Scatter
As collimation decreases (__1__ field size)=__2__ production of scatter and __3__ pt. doses it’s decreased contrast/__4__ density.
- Increased
- Increased
- Increased
- Increased
As collimation increases (__1__ field size)=__2__ production of scatter and __3__ pt. dose with increased contrast/__4__ density.
- Decreased
- Decreased
- Decreased
- Decreased
First step in pt. protection?
OPTIMUM COLLIMATION
Significant COLLIMATION may require an increase in _______
MAS
There is _____ unsharpness on the anode side of the tube.
Less
Simplest type of collimator. Piece of lead with a hole in it. NOT variable and not used often.
Aperture Diaphragm
Cone=shaped like a __1__ and correlates to divergent of beam.
Cylinder=shaped like a __2__ and can extend down. Used mostly for __3__, though not used much anymore. ___4___ are better than __5__. Are __6__ variable.
- Megaphone
- Tube
- Skull work
- Cylinders
- Cones
- NOT
Best type of variable beam restricting device. Two sets of adjustable lead shutters and a light source for centering.
Box-Type Collimator
NCRP says COLLIMATION must be wishing ______ of the SID
+/- 2%
Nine Penny Test checks ______.
COLLIMATION
PBL/AC only used with __1__ due to sensors located there. It was a law (__2__) that all manufactured equipment have them, but no longer a law, although most manufactures still include it.
Can be overrode with a __3__, but not suggested. Can increase __4__ when it is on (“__5__”), but no larger than IR.
- Bucky
- 8/1/74-1994
- Key
- Collimation
- Cone down
__1__ invented the stationary grid in 1913. Typically used if part is __2__ or thicker & __3__ kVp or above. Does NOT decrease production of scatter, but does increase __4__ and __5__.
- Gustave Bucky
- 10cm.
- 60
- Contrast
- Pt. Dose
Grid Ratio=
Height of Pb strips/Distance between Pb Strips
Interspace get materials can be __1__ or __2__.
- Organic
2. Inorganic
Scatter is a result of __1__, which results from an interaction with an __2__ Shell Electron. End Results=Compton or __3__ X Ray Photon. __4__ color on radiograph.
- Compton
- Outter
- Weakened
- Gray
Grid Frequency=number of __1__ lines/inch or cm. Typically __2__ Pb lines/in (25-45 Pb/cm)
- Pb
2. 60-110
5: 1=__1__
6: 1=__2__
8: 1=__3__
12: 1=__4__
16: 1=__5__
- 75%
- 85%
- 90%
- 95%
- 98%
Grid Conversion Formula (GCF)»mAs1/__1__=__2__/__3__
- MAs2
- GCF 1
- GCF 2
Linear Grids=__1__ lines run in one direction only (__2__). Used most often. Can angle __3__ or __4__ but not ACROSS grid lines.
- Pb
- Head to toe
- Cephalic
- Caudal
Pb lines run at right angle to one another. Cannot angle in any direction. MOST restrictive.
Crossed or Cross Hatch
These grids have Pb lines parallel to one another and have no set focusing distance.
Parallel or Non-Focused
Angled lead lines to use in a specific focusing distance
Focused Grids
Where points converge in space from a focused grid.
Convergent Point
