Chapter 4 Rad 2 Flashcards
KVP controls (3)
Energy, Penetration, Quality
MAS controls (3)
Quantity, Amount, Number of Electrons
Inorganic Grid Interspacer
Aluminum
Organic Grid Interspacer
Cardboard, Balsa Wood
Adult skull is age ___ & up?
6 years old ( 75kvp)
Name 2 destructive illnesses that would make you decrease technique
COPD, Pneumothorax
Name 2 Additive illnesses that would have you increase technique
Pneumonia, Pleural Effusion, Atelectasis
Formula for Grid Ratio
Heigh of PB strips/ Distance between Pb Strips
Do grids decrease the production of scatter?
No
Scatter is _____
density
When dealing with grids ___ on the Left ___ on the right
divide on the left, Multiply on the Right
Ratio 5:1 has what conversion factor?
2
Ratio 6:1 has what conversion factor?
3
Ratio 8:1 has what conversion factor?
4
Ratio 12:1 has what conversion factor?
5
Ratio 16:1 has what conversion factor?
6
Every time you double the speed you must ____ the mas in ___
cut, half
Every time you cut the speed in half you must ___ the ___
Double, Mas
Increased Screen Speed =
Decreased Patient Dose and Decreased Detail
Decreased Screen Speed =
Increased Patient Dose and Increased Detail
Inverse Square Law Formula
old mAs/ New mAs = old distance squared/ new distance squared
If you double the distance from the source or double the SID the exposure will be?
One fourth as strong
If you cut the distance from the source in half or cut the SID in half the exposure will be?
Four times as strong
Above 90 kVp = if kV increases by 15
cut mas in half
Above 90 kVp = if kV decreases by 15
double mas
Below 90 kVp= if kV increases by 10
cut mas in half
Below 90 kVp= if kV decreases by 10
double mas
In order to see a visible change in density you must increase or decrease the mAs by?
30%
as mas is _______ the quantity of radiation is increased and density increases.
increased
Milliamperage and Exposure Time are ______ related when maintaing the same mAs.
inversely
the minimum change needed to correct for a density error is determined by multiplying or dividing by?
2
high contrast = ____ scale, ____ kv
short scale, low KV
Low contrast = ____ scale, ____kv
long scale, high kv
____ influences density, ____ controls density
kVp, mAs
Geometric factors of detail (3)
OID, SID, FS
What controls contrast?
KV
High kV creates more densities but with fewer difference low contrast _____ scale
long
Low kV creates fewer densities but with greater differences high contrast _____ scale
short
Increased scatter = ______ contrast
decrease
Decreased scatter = ______ contrast
increased
FS size affects ______
recorded detail/ spatial resolution
Penumbra
Unsharpness
Umbra
Recorded Detail
Magnification =
size distortion
True=
Shape Distortion
For every 1’’ OID you must increase SID by ____ to compensate
8’’
Where is scatter produced?
In the patient
What is the 1st step in protection?
Collimation
Generators with more efficient output ( like a 3 phase ) require ___ technique settings?
LOWER
If the tube operates at 70kvp or higher must have ___ of filtration?
2.5mm/al
main purpose of tube filtration is to
decrease patients skin dose
Increased collimation = ______ scatter and density
decreased
Positive Contrasts
BArium, Iodine
Negative Contrast
Air CO 2
