PAM1020 - The X-Ray Tube Structure

• What is the main focus of Lecture 09?

  The X-Ray Tube Structure
• What components are covered in the X-Ray Tube Structure?

  • Outer tube housing
  • Glass envelope
  • Cathode
  • Anode
• What is the purpose of the outer tube housing in an X-ray tube?

  Physical, radiation, and electrical protection
• What materials are used for the tube housing lining?

  Steel and lead lining
• What is the function of the exit window in the tube housing?

  Allows X-rays to exit the tube
• How are electrons produced in the X-ray tube?

  Electrons are produced at the cathode
• What is the role of the anode in the X-ray tube?

  To convert electron energy into X-rays
• What is the source of electrons in the X-ray tube?

  The cathode
• What is thermionic emission?

  Electrons escaping from a heated filament
• How does the focusing cup affect electron flow?

  It controls the stream of electrons hitting the anode
• What happens to electrons when the filament is heated above 4 amps?

  Electrons are 'boiled off' from the filament
• What is the typical wire width of the filament in the cathode?

  0.1mm-0.2mm
• What is the purpose of the rotating anode?

  To increase heat dissipation
• What is the efficiency of X-ray production in the anode?

  Less than 1%
• What materials are commonly used for anode targets?

  Tungsten and molybdenum
• What factors affect the efficiency of the X-ray process?

  Atomic number and electron energy
• What is the atomic number of tungsten?

  74
• Why is a vacuum necessary in the X-ray tube?

  To prevent interruption of the electron beam
• What is the typical melting point of tungsten?

  3410 ºC
• What happens to most X-rays produced in the tube?

  They are attenuated within the patient
• What is the overall proportion of energy that creates an X-ray image?

  1.3 x 10$^{-12}$ %
• What are the primary functions of the anode assembly?

  1. Convert electron energy into X-rays
  2. Dissipate heat created in the process
  3. Act as an electrical conductor
• What is the typical current produced by a cathode in an X-ray tube?

  100 mA
• How many electrons travel from the cathode to the anode per second at 100 mA?

  6 x 10$^{17}$ electrons
• What is the significance of the space charge effect in the cathode?

  It contains the cloud of electrons around the filament
• What is the role of the light beam diaphragm in the X-ray tube housing?

  To collimate the X-ray beam
• What is the purpose of filtration in the X-ray tube?

  To remove low-energy X-rays
• What is the effect of high voltage cables in the X-ray tube?

  They provide electrical power to the tube
• How does the anode material affect X-ray production?

  Higher atomic number increases interaction probability
• What is the typical energy of electrons in keV for each kV of voltage?

  1 keV of energy
• What happens to the electrons as they move towards the anode?

  Their electrical potential energy converts to kinetic energy
• What is the relationship between voltage and electron energy in the X-ray tube?

  Higher voltage results in higher electron energy
• What is the typical depth of initial interactions at the anode?

  0.5mm
• How many interactions can electrons undergo before leaving the anode?

  Around 1000 interactions
• What is the typical number of electrons hitting the target per mA?

  6.3 x 10$^{15}$ electrons
• What are the main components of the X-ray tube?

  • Outer tube housing
  • Glass envelope
  • Cathode
  • Anode
• What are the strengths and weaknesses of stationary and rotating anodes?

  Strengths of stationary anodes:

  • Simplicity
  • Lower cost

  
  

  Weaknesses of stationary anodes:

  • Poor heat dissipation
  • Limited anode load

  
  

  Strengths of rotating anodes:

  • Better heat dissipation
  • Higher anode load

  
  

  Weaknesses of rotating anodes:

  • More complex
  • Higher cost