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Imaging II Quiz 1
Question | Answer |
---|---|
What are the requirements for x-ray production/emission? | 1. A source of electrons 2. Electrons moving at high speeds(high voltage) 3. Abrupt stopping of electrons. |
What is nice to have but not needed for x-ray production/emission? | 1. Appropriate target material 2. A vacuum tube |
What is the benifit of having a vacuum tube? | The tube will be void of ambient air molecules. Air has mass and will take energy away from the electrons = fewer x-rays produced. |
Where is the filament located? | Located on the cathode side of the tube, within the focusing cup. |
What does the filament do? | Controls the f.s. size and provides the source of electrons. |
What is the filament made of? | 98% Tungsten (W), 2% Thorium |
Why use Tungsten? | Because it is an ecellent termionic emmiter and it does not vaporize easily. |
Why add Thorium to the Tungsten? | Added to prolong tube longevity |
What is blooming or off-focus radiation? | Radiation that is made from electrons striking things other then the target material. Produces a ghosting effect around the outside of your collimation (NOT SCATTER!!!) |
Blooming/Off-focus radiation my comprise how much of the primay beam? | 25-30% |
Where is the focusing cup? | Located on the cathode side of the tube. |
What is the focusing cup made of? | Molybdenum (MO) or Nickel |
What does the focusing cup do? | It focuses the electrons into a tighter space cloud/charge, helps reduce off focus radiation. |
What does the anode do? | provide mechanical support for the target. Contains the target in generl radiography. |