X-Ray Production & Equipment Flashcards
What are the 3 components of the X-ray tube ?
Anode, cathode, glass envelope.
What are the 2 components of the cathode ?
Filament and focussing cup.
What are the 2 components of anode ?
Target and heat dissipating block.
What is the filament ?
Coiled wire which low voltage and high current is passed through it to heat to 2200 degrees causing electrons to be released from the wire by thermionic emission causing a cloud of electrons to form around the wire.
What is the filament made out of ?
Tungsten.
Why is the filament made out of tungsten ?
Withstands high heat.
High atomic number - large amount of electrons to protons - 74.
What is the focussing cup ?
Metal plate around filament which is negatively charged and repells the electrons which is shaped to focus electrons at a point on the anode.
What is the focussing cup made of ?
Molybdenum.
What are the properties of molybdenum which makes it appropriate to be the focussing cup’s material ?
Poor thermionic emitter.
Withstands high temperatures.
Explain the relationship between the cathode and anode.
Electrons from filament are repelled and attracted to anode due to high potential difference created by electric current between cathode and anode.
Electrons accelerate at high speed causing increased kinetic energy on collision with anode.
What is the anode ?
Metal block which is a target for electrons accelerating from filament which produces photons and heat.
What is the anode made of ?
Tungsten - as it produces x-ray photons.
Define focal spot.
Target where photons (x-rays) are produced i.e. x-ray source.
What is the function of the heat dissipating block ?
Prevents over heating by causing heat dissipation via thermal conduction.
What is the heat dissipating block made of ? And why ?
Copper - good thermal conduction abilities and can withstand high temperatures.