X-ray tube

• What are the design features of the stationary anode X-ray tube?

  Design features include the glass envelope, cathode, filament, anode, target, and tube housing.
• What is the function of the glass envelope in an X-ray tube?

  The glass envelope supports a vacuum and holds electrodes in precise positions.
• Why is the glass envelope made of borosilicate glass?

  It is strong enough to support a vacuum and prevents electron collisions with gas atoms.
• What is the purpose of the tube housing in an X-ray tube?

  The tube housing shields users from radiation exposure and protects the tube from damage.
• How does the tube housing contribute to thermal dissipation?

  The housing is filled with pure oil that acts as an insulator and coolant.
• What happens if the oil in the tube housing gets too hot?

  A microswitch may disconnect the tube’s kV to prevent further exposures.
• What are the two types of X-ray tubes mentioned?

  Stationary anode and rotating anode X-ray tubes.
• What is the typical operating temperature of the filament in a stationary anode X-ray tube?

  The filament operates at an idling temperature and is heated to 2400° C during exposure.
• What material is the filament in the cathode made of?

  The filament is made of tungsten.
• Why is tungsten used for the filament in X-ray tubes?

  Tungsten has a high melting point and low vapor pressure, preventing evaporation.
• What is the role of the focusing cup in the cathode?

  The focusing cup directs the electron beam towards the anode target.
• What is the atomic number of tungsten?

  The atomic number of tungsten is 74.
• How does the anode function in an X-ray tube?

  The anode acts as a positive charged target and conducts heat away from the target.
• What is the significance of the temperature gradient established in the anode during exposure?


  Heat travels from hot to cold, allowing for effective cooling of the anode.
• What is the purpose of the target material in the anode?

  The target material converts the kinetic energy of bombarding electrons into X-rays.
• How does the focusing cup affect the electron beam in an X-ray tube?

  The focusing cup creates a negative bias that directs electrons towards a smaller area on the anode.
• What is the effect of the finite size of the X-ray source on imaging?

  It creates a penumbra or geometric unsharpness around the X-ray shadow.

  
• What are the three basic principles of electrical safety in X-ray tubes?

  1. Insulation of live components using oil.
  2. Earthing of component housings to maintain earth potential.
  3. Use of layers of rubber and other insulators to prevent current flow.
• What is the purpose of the tube port in an X-ray tube?

  The tube port allows the useful beam to exit the tube.

  
• What is the role of oil in the tube housing?

  Oil acts as an insulator and coolant, helping to dissipate heat.
• How does the angulation of the target affect X-ray production?

  It allows free access for electrons and a wide exit path for emerging X-rays.

  
• What happens to the electrical safety of the X-ray tube if the insulation fails?

  It could lead to electrical hazards for users if live components are exposed.
• What is the significance of the high atomic number of tungsten in X-ray production?

  A high atomic number allows tungsten to efficiently convert kinetic energy into X-rays.
• What is the melting point of tungsten?

  The melting point of tungsten is 3370°C.
• What is the purpose of the dual focus in X-ray tubes?

  Dual focus allows for two filaments side by side to enhance imaging options.
• How does the structure of the high-tension cable contribute to electrical safety?

  It connects the copper wire braiding to the shield and transformer casing, ensuring earthing.
• What is the role of the re-entrant seals in the glass envelope?

  They allow for thermal expansion and prevent cracking of the glass envelope.
• Why is the focusing cup rounded?

  It prevents the buildup of high amounts of static charge.
• What is the purpose of the negative bias on the focusing cup?

  It controls and focuses the electron beam emitted by the cathode towards the anode target.
• How does the heat transfer from the target to the tube housing occur?

  Heat is transferred by convection through the oil and by radiation across a vacuum.
• What is the significance of the low vapor pressure of tungsten?

  It prevents the filament from evaporating and maintains its integrity.
• What is the effect of the negative potential on the focusing cup?

  It reduces the area of the focal spot by directing electrons more precisely.
• What is the role of the cathode in the X-ray tube?

  The cathode emits electrons that are accelerated towards the anode target.

  
• How does the design of the X-ray tube minimize radiation leakage?

  The tube housing is coated with lead-lining to minimize radiation leakage.
• What is the purpose of the light beam diaphragm in an X-ray tube?

  The light beam diaphragm helps to define the useful beam that exits the tube.
• What happens to the electrons when the exposure button is pressed?

  Electrons are accelerated towards the target when kV is applied across the tube.
• What is the significance of the high melting point of tungsten in X-ray production?

  It allows tungsten to withstand the high temperatures generated during X-ray production.
• How does the structure of the X-ray tube contribute to electrical safety?

  The structure includes insulation, earthing, and protective housing to prevent electrical hazards.

  
• What is the role of the copper cylinder in the anode?

  The copper cylinder supports the target and conducts heat away from it.
• What is the purpose of the microswitch in the tube housing?

  The microswitch disconnects the tube’s kV if the oil gets too hot.