X-Ray Tube Flashcards
What are the primary components necessary for X-ray production?
*Source of electrons
*appropriate target material
*high voltage
*vacuum
What is the function of the cathode assembly in an X-ray tube?
Produce thermionic cloud, conduct high voltage, focus electron stream
The cathode assembly is the negative side of the X-ray tube.
What materials can the filament in the cathode assembly be made of?
- Thoriated tungsten
- Rhenium
- Molybdenum
Thoriated tungsten is most commonly used due to its high melting point and resistance to vaporization.
What is the purpose of the focusing cup in the cathode assembly?
Narrows the thermionic cloud
The focusing cup is made of nickel and helps direct electrons toward the anode.
What is the space charge effect?
Negative charges from emitted electrons oppose additional electron emission
This effect limits the mA ranges of the X-ray tube.
True or False: The anode assembly is the positive side of the X-ray tube.
True
The anode serves as the target surface for electrons and conducts high voltage.
What are the two types of anodes?
- Stationary
- Rotating
Rotating anodes provide better heat dissipation during operation.
What is the primary thermal conductor in the anode assembly?
Anode (target)
The anode conducts heat away from the focal track.
Why is tungsten the material of choice in the anode target?
- High atomic number
- High melting point
- Heat-conducting ability
What is pitting in the context of an X-ray tube?
Vaporization of target track material due to normal use
Pitting reduces the efficiency of the tube.
What is the effective focal spot?
Area of the focal spot projected out of the tube
It is influenced by the actual focal spot, filament size, and anode target angle.
Fill in the blank: The __________ effect results in greater radiation intensity on the cathode side of the X-ray tube.
anode heel
This phenomenon is due to the geometry of the angled anode target.
What does the stator do in an X-ray tube?
Turns the anode
The stator is the only part located outside the vacuum of the envelope.
What is the role of the dielectric oil in an X-ray tube?
Insulates high-voltage components, absorbs heat
The oil helps maintain the temperature and prevents electrical hazards.
What can cause ghosting of structures in X-ray imaging?
Off-focus or extrafocal radiation
This occurs when high-voltage electrons produce scattered photons.
What is the primary purpose of the protective housing of an X-ray tube?
Controls leakage and scatter radiation, isolates high voltages, cools the tube
The housing is typically made of steel and lined with lead.
The cathode assembly consists of?
Filament
Focusing cup
Associated wiring
The anode heel effect is most noticeable at?
Short SID
Large IR
small focal spot
The rotor revolves at what speed?
3200 to 3600
High speed rotating anode rotates at what speed?
10000 to 12000
Envelope is made with what kind of glass
Pyrex
Anode assembly consists of
Anode (target)
Stator
Rotor
Functions of the anode assembly
Target surface for electrons
Conducts high voltage
Primary thermal conductor
Why is tungsten used for the filament
High melting point
Difficult to vaporize
