Chapter 2 from Worksheets Flashcards
What type of glass is used for a x-ray tube?
PYREX
If a tube operates at 70 kV or above, what is the amount of filtration it must possess?
2.5mm of Al. (or it’s equivalent)
When electrons strike anode what percent is heat?
99%
When electrons strike anode what percent is x-ray?
1%
The majority of the x-ray beam is created through a process called what?
Bremsstrahlung
Minority of the x-ray beam is created through a process called?
Characteristic
A dual focus tube has what
2 filaments/cathodes and 1 anode
Leakage from and x-ray tube cannot exceed…..
100mR/hr @ 1 meter
The average anode rotates….
3,000-10,000rpm
The cathode possesses what type of charge?
negative
The anode possesses what kind of charge?
Positive
What type of rotor rotates the anode?
Induction
The projected or effective focal spot is smaller than the AFS
Line focus principle
What 2 purposes does the glass envelope serve in the xray tube?
A. Insulation from electrical shock
B. Dissipates heat
Below 69kV, 100% of the xray beam is the result of
Brem’s radiation
When electrons drop for outer shell to fill holes in inner shells
Characteristic Radiation
When electrons approach target of atom and rapidly decelerate and change direction
Bremsstrahlung “Braking”
Many energies in a beam (not all same)
Polyenergetic
What type of metal can be added to the anode to make it lighter and able to withstand great amounts of heat?
Graphite
“Cut Off” point in technique that would cause you to select a large focal spot?
100mAs
If you select a large focal spot what do you sacrifice?
Detail
Unit of frequency?
Hz
Steeper anode angle will result in
Better Detail
Intensity of the xray beam is greater on which side?
Cathode side of tube
Three heat unit equations
- Single Phase
- Three Phase
- High Frequency
Single Phase Equation
(mA)(time)(kV)
Three Phase Equation
(mA)(time)(kV)(1.35)
High Frequency Phase Equation
(mA)(time)(kV)(1.40)
If too high heat units are being produced how do you fix it and still maintain detail?
Decrease mAs and increase kV
If you decrease kV then what do you do to mAs?
DOUBLE it
If you increase kV then you do what to mAs?
cut in half
Do not hold down rotor button without making an exposure
Don’t Boost and Hold
Amount of filtration that reduces intensity of beam to half its original value
Half-Value Layer
When performing an AP projection of the thoracic spine, in order to use the Anode Heel Effect to your advantage; you should place the cathode end of tube over which aspect of spine?
Inferior
Main purpose of filtration
Decrease Patient’s Skin Dose
Three ways to enhance anode heel effect?
- steep/small anode angle
- short SID
- Large IR
Total Filtration=
ADD+INHERENT
2.5mm+
2.0+0.5
X-Ray of part with different thicknesses or compensation for air filled lungs
When To Use Wedge Filters
