Xray tube design

• What is the primary product of X-ray production?

  Heat
• Why is heat dissipation important in X-ray tubes?

  It prevents inefficient X-ray production
• What are the main components inside an X-ray tube cylinder?

  • Envelop (glass or metal ceramic)
  • Cathode (negative polarity)
  • Anode (positive polarity)
• What is the role of the cathode in an X-ray tube?

  To support the filament
• What happens when a current passes through the filament?

  It heats up, causing atomic vibrations
• What is the effect of atomic vibrations in the filament?

  Electrons become dislodged from atoms
• What is applied between the cathode and anode to accelerate electrons?

  Potential difference
• What is the minimum potential difference required to generate EMR?

  $5 \text{kV}$
• What is the typical range of potential difference needed to generate X-ray photons?

  Between 70,000 - 150,000 volts
• What is the purpose of an evacuated chamber in an X-ray tube?

  • Enables electrons to pass without interactions
  • Prevents stray electrons from interacting with the envelope
• What can happen if electrons stray and interact with the envelope?

  It can cause arcing
• What is the role of the anode in an X-ray tube?

  To create X-ray photons
• What is the function of the window in an X-ray tube?

  Allows X-ray photons to escape
• How do X-ray photons exit the tube?

  Perpendicular from the target
• Why must X-ray photons be prevented from interacting with others in the room?

  To ensure safety and reduce exposure
• What is the benefit of a rotating anode in an X-ray tube?

  • Increases surface area for electron impact
  • Improves heat dissipation
• What is the purpose of the focusing cup in an X-ray tube?

  To concentrate the electron beam
• Why is tungsten used in the filament of an X-ray tube?

  It has a low thermionic work function
• What is the significance of tungsten's high melting point?

  It withstands heat generated during X-ray production
• What does low vapor pressure in tungsten prevent?

  It prevents evaporation in a vacuum
• How does the dual focus system benefit X-ray production?

  It allows changing electron focus size
• What are the two forms of filament arrangements in dual focus tubes?

  • Series: fine focus on top of broad focus
  • Parallel: two filaments side by side
• What is the advantage of a broad focus filament?

  Better heat dissipation
• What does geometric unsharpness or penumbra refer to?

  Overlapping portions
• What is the size of the fine focus filament's area?

  0.6 mm squared
• What is the size of the broad focus filament's area?

  1.2 mm squared
• What is the role of the focusing cup in an X-ray tube?

  • Sits behind the filament
  • Focuses electrons onto a smaller area of the anode
  • Keeps electrons tightly packed
• What happens if electrons are not tightly packed?

  They scatter and miss the target
• What is the importance of the negative bias from the focusing cup?

  It decreases the interaction area on the anode
• What is the effect of angling the target in an X-ray tube?

  • Reduces geometric unsharpness
  • Decreases penumbra
• What is the actual focal spot size?

  Height and width of the electron beam
• What is the effective or nominal focal spot size?

  What is projected down from the target
• What are the two types of anodes in X-ray tubes?

  • Stationary anode
  • Rotating anode
• What is the advantage of a rotating anode?

  Better heat dissipation
• What is the purpose of the rotating disc in an X-ray tube?

  Increases surface area for electron impact
• Why is tungsten used as the target in the anode?

  It has a high melting point
• What happens when incident electrons interact with tungsten's nucleus?

  They release energy as EMR
• What is characteristic radiation?

  When incident electrons interact with orbital electrons
• What are the benefits of tungsten as a target material?

  • High atomic number for efficient interaction
  • Good thermal conductivity for heat dissipation
  • Similar expansion rate to copper
• Why is the angulation of the anode important?

  It aids in dissipating heat