X-ray Tube & Components

• First generation of X-Ray producing tubes was the Crookes Tube
• Crookes Tube:

  • Simple tube with two electrodes at opposite ends of a semi-vacuum tube
  • When high voltage electricity was delivered to opposite ends of the tube, electrons would flow within the tube in a straight line
• In 1913, Edward Coolidge invented the Coolidge Tube, which is the framework of modern X-Ray Tubes
• Parts of the X-Ray Tube and their roles:

  • Cathode: Negatively charged Tungsten filament encased in a Focusing Cup
  • Anode: Positively charged, attracts rapidly moving electrons to create X-Rays
  • Anode Stem, Rotor, Bearings, Glass Envelope, Stators
  • Glass Envelope: Houses the Anode & Cathode, creates an air-free vacuum, protects against oxidation & corrosion
  • Induction Motor: Turns the Anode without touching it
• Tube Housing:

  • Encapsulates the entire X-Ray Tube to prevent X-Rays from spreading
  • Responsible for mechanical and electrical connections for the X-Ray Tube
• 1. Rays are produced by:

  • Source of Electrons
  • Rapid acceleration and deceleration of electrons
• 1. Rays escape the tube through the only opening in the X-Ray Tube's Housing, where they are aimed and collimated
• How X-Rays are made:

  • Cathode is charged & heated with electrical current, resulting in the dissociation of electrons from the filament creating an Electron Cloud (Thermionic Emission)
  • Voltage is applied to the filament giving a strong negative charge, which pushes the Electron Cloud toward the Anode
  • The negatively energized electrons are drawn to the positively charged Anode, resulting in X-Rays and heat