Ch. 5 The X-Ray Tube Flashcards
what is the rotating anode disc mounted on and why
copper shaft with a molybdenum core, copper for thermal and electric conductive properties, molybdenum for low-thermal conductivity and light weight but strong alloy
Heat unit capacity formula
kVp x mA x s x c x # of exposures
what is the stator made up and where is it located
electromagnets arranged in pairs around the rotor, located outside the tube enclosure
what is the core of the anode disc made of and why
molybdenum for low thermal conductivity and light but strong alloy
general purpose tubes are capable of rotating the anode at what speed
3400 rpm
angle of target face is <45 degrees
line focus principle
what is the correction factor for three-phase, 6 pulse generator
1.35
what is tungsten’s melting point
3400c; 6152f
what is tungsten’s atomic number
74
what is the correction factor for high frequency generators
1.45
what is sometimes added to tungsten on the anode target and why
Rhenium to increase thermal capacity and tensile strength
what do we call the cloud of electrons in the focusing cup
space charge
primary purpose of enclosure of the x-ray tube
maintain vacuum
specialty tubes are capable of spinning the anode at what speed
10,000 rpm
what is the rotating disc coated with and why
tungsten for its high melting point and thermal conductivity
anode disc mounts onto shaft made of what
copper for its thermal and electrical conductive properties
molybdenum core for low thermal conductivity
origin of the x-ray beam; area seen from patients perspective
effective focal spot
area being bombarded by the filament electrons
actual focal spot
what is the single phase generator correction factor
1
glass envelopes are usually made from
pyrex glass/borosilicate glass
what is the rotor made up of and where is it located
iron core - iron bars embedded in copper shaft surrounded by coils, located in center of stator within enclosure
what circuit are the filaments connected to
filament circuit
the anode is rotated using what
induction motor
where does the voltage come from and go to
autotransformer to the step-up transformer
what are filaments made of
tungsten with 1-2% thorium
appropriate leakage allowed outside the housing
1mGy/hr at 1 meter
filament heats and emits electrons to the point it can’t produce anymore, what do we call this
saturation current
what is the correction factor for three-phase, 12 pulse generator
1.41
what is the focusing cup made of
nickel
what is the rotating anode disc made of and why
molybdenum for low thermal conductivity coated in tungsten for high melting point and thermal conductivity
how big is the target window on enclosures usually
5 cm
what is the focusing cup connected to
secondary circuit
as tubes age, vaporized tungsten from the filament deposits on the inside of the glass envelope known as
sun tanning
what is the x-ray tube coated in
di-electric oil
why is tungsten used for the filament and why is thorium added
tungsten’s high melting point and it doesn’t vaporize easily, thorium is added to increase thermionic emission and extend filament life
what does the stationary anode consist of
tungsten button inside a copper rod
what are the target angle’s for general purpose tubes
7-18 degrees, 12 most common
systems can record and display many shades of grey in digital technology known as
dynamic range
