What is the negative electrode of an x-ray tube called?
The cathode
What is the positive electrode of an x-ray tube called?
The anode
What is the process called when a heated filament releases electrons?
Thermionic emission
What material is the x-ray tube filament made of?
Thoriated tungsten
What is the negatively charged metal shroud around the filament called, and what does it do?
The focusing cup — electrostatically focuses the electron beam toward the target
How many filaments does a dual-focus x-ray tube have?
Two, side by side, giving a large and small focal spot
What is the anode's target material in a general-purpose x-ray tube?
Tungsten
What is tungsten's atomic number?
74
What is tungsten's melting point as the anode target material, compared to copper's?
Over 3,400°C, vs. copper's 1100°C
What material is the anode stem made of, and why?
Molybdenum — a poor heat conductor, so heat stays in the target disc instead of leaking into the bearings
What part, outside the tube's glass or metal envelope, creates the rotating magnetic field that spins the anode?
The stator
What part, attached to the anode inside the tube, is driven by the stator's rotating magnetic field?
The rotor
In the line-focus principle, does decreasing the target angle make the effective focal spot smaller or larger?
Smaller
What is the name of the design principle that lets an angled target have a large actual area but a small effective focal spot?
The line-focus principle
Which is always larger: the actual focal spot or the effective focal spot?
The actual focal spot
Due to the heel effect, is the x-ray beam more intense on the cathode side or the anode side?
The cathode side
Does a smaller anode target angle make the heel effect more or less pronounced?
More pronounced
For a chest radiograph, should the cathode be positioned superiorly or inferiorly?
Inferiorly
For an abdomen radiograph, should the cathode be positioned superiorly or inferiorly?
Superiorly
What is the term for filtration provided by the x-ray tube's own glass or metal enclosure and window?
Inherent filtration
What material is added filtration made of?
Aluminum (Al) sheets
What does adding filtration do to the x-ray beam's average energy, and to patient dose?
Increases average energy ("hardens" the beam) while reducing patient radiation dose
What is the single-phase heat unit formula?
HU = kVp × mA × s
At 98 kVp and 120 mAs (single-phase), how many heat units does an exposure generate?
11,760 HU
Which anode design has greater heat capacity — stationary or rotating?
Rotating