Chapter 7 (The X-Ray Tube) Flashcards
What are the two main components of an x-ray tube?
Cathode and anode.
What is the function of the cathode?
Produces free electrons via thermionic emission.
What is the function of the anode?
Stops electrons and produces x-rays.
What material is the filament made of?
Thoriated tungsten.
What does the focusing cup do?
Directs electrons toward the anode target.
What are the two types of anodes?
Stationary and rotating.
Why is tungsten used as an anode target?
High atomic number, high melting point, good heat dissipation.
What is the line-focus principle?
Angling the anode to create a smaller effective focal spot.
What is the heel effect?
X-ray intensity is stronger on the cathode side.
How much of the electron energy is converted to heat?
99% heat, 1% x-rays.
What is the purpose of the rotating anode?
Dissipates heat more efficiently.
What is the space charge effect?
Electron cloud formation around the filament that limits emission.
What is the most common cause of abrupt tube failure?
Tungsten vaporization and arcing.
What does the protective housing of an x-ray tube do?
Reduces leakage radiation and prevents electric shock.
What is tube rating?
The maximum exposure limits to prevent tube damage.
What does the anode angle affect?
Focal spot size and heel effect.
What are the three ways heat is dissipated in an x-ray tube?
- Radiation
- Conduction
- Convection
What is the function of the rotor and stator?
Rotate the anode via electromagnetic induction.
What is off-focus radiation?
X-rays produced outside the focal spot.
What happens if the tube is not properly warmed up?
Anode cracking and early tube failure.
