X-Ray Tube and Production Flashcards

Flashcards about X-Ray Tube and Production

What is Ionisation?

Process in which electron is given enough energy to break away from atom resulting in formation of 2 ions and chemical changes

What is an x-ray photon?

Photon travelling through space with short wavelengths and high frequency, therefore has a high penetrative power.

What is an X-Ray Tube?

Glass vacuum that converts electrical energy into x-radiation and heat

What is the Cathode?

Coiled filament wire that acts as a source of electrons

What are the properties of Tungsten?

Low work function, good thermionic emitter, doesn't easily evaporate, flexible, tough

What is the role of the Nickel Focusing Cup?

Negatively charged, prevents spread of electrons, condenses electron beam to small area

What is the Anode?

Tungsten alloy target disc for electrons that produces x-ray photons

What are the properties of Tungsten in the Anode?

Stops electrons abruptly, high positive charge, high melting point, low vapor production

What is the Anode Stem composed of and what is its role?

Made from molybdenum, supports anode rotating at +3000rpm, resists heat, conducts electricity

What are the main components of a High Voltage Generator?

Transformers, auto transformer, filament circuit, rectifiers, control panel

What is the role of a Three Phase Generator?

Inverts negative voltage and sends highest of 3 phases to x-ray tube

What does a Rectifier do?

Changes alternating current of high voltage transformer to direct current

What is Half-Wave Rectification?

Removes negative side of sinusoids waveform to have constant supply of energy

What is Full-Wave Rectification?

Utilises both + and - half cycles of high tension transformer

What does a Constant Potential Generator produce?

Continuous uninterrupted voltage

What is Thermionic Emission?

Emission of electrons from heated metal

What is the purpose of the Control Panel in an X-Ray circuit?

Select appropriate kVp, MAs and exposure time

At the anode, electrical energy is converted to…?

99% heat, 1% x-ray photons

What features facilitate heat dissipation in an X-Ray tube?

Rotating anode, Tungsten, Focal spot, Glass envelope, Insulation oil, Steel housing/lead casing

What is Characteristic Radiation?

High energy electron collides with inner shell electron, emitting energy

What is Bremsstrahlung Radiation?

Electron travels close to nucleus, loses kinetic energy and path deflected

What determines the acceleration of electron from cathode to anode?

Altering the kVp

What does Altering current over set period of time at cathode and anode do?

Determines the amount of x-ray photons present and the number of e- produced

How does a Linear Accelerator work to achieve Therapeutic Energies?

Electrons accelerated in straight line by radio-frequency waves

What is X-Ray Tube Rating?

Safety parameters that limits damage to x-ray tube

What does the amount of heat depend on when considering head loading characteristics?

Voltage (kV), Current (mA), Length of exposure (s), Type of voltage waveform, Number of exposure taken in rapid sequence

What is the energy range for Superficial X-Rays (Mammography)?

35-60kV

What is the energy range for Diagnostic X-Rays (General X-Ray)?

20-150kV

What is the energy range for Orthovoltage X-Rays (Superficial Therapy)?

200-500kV

What is the energy range for Supervoltage X-Rays (Superficial Therapy)?

500-1000kV