xray tubes

• What is the purpose of the focusing cup in an X-ray tube?

  To focus the electron beam
• The anode of an X-ray tube is made of tungsten-rhenium alloy because of its high atomic number and high melting
• The anode in an X-ray tube rotates to distribute heat evenly across the focal track.
• What type of motor is used to rotate the anode in an X-ray tube?

  Induction motor
• Steps in the operation of an induction motor in an X-ray tube

  1️⃣ Current supplied to stator

  2️⃣ Magnetic field rotates

  3️⃣ Currents induced in rotor

  4️⃣ Rotor becomes magnetised

  5️⃣ Magnetic repulsion causes rotation
• A small focal spot in an X-ray tube is ideal for heat dissipation but can reduce image sharpness.

  False
• What principle allows a large actual focal spot size to produce a small effective focal spot size?

  Line-focus principle
• The anode heel effect results in a less intense X-ray beam on the anode
• A vacuum is required in an X-ray tube to allow electrons to accelerate without colliding with air molecules.
• What is the process called that releases electrons from the heated filament in an X-ray tube?

  Thermionic emission
• What provides the force to accelerate electrons in an X-ray tube?

  High voltage
• During deceleration of electrons in the anode, approximately 99% of their kinetic energy is converted into heat
• Match the X-ray tube parameters with their descriptions:

  mA ↔️ Number of electrons produced

  kV ↔️ Voltage to accelerate electrons

  Exposure time ↔️ Duration of X-ray emission
• What is the formula for calculating mAs in an X-ray tube?

  $mAs =$$mA \times time$
• Inherent filtration in an X-ray tube is equivalent to approximately 1 mm of aluminum
• What type of metal is commonly used for added filtration in an X-ray tube?

  Aluminum
• The glass enclosure of an X-ray tube is airtight to maintain a vacuum.
• What material is used to line the protective housing of an X-ray tube to prevent leakage radiation?

  Lead