The X-ray Tube Flashcards
it is the most frequent used system
ceiling support
it consists of two sets of rails mounted to the ceiling directly over the radiographic table
ceiling support
external structure has 3 components:
support structure
protective housing
glass or metal envelope
internal structure has 2 components:
anode
cathode
the rails are mounted perpendicular to each other so that the tube can move longitudinally along the length of the table and transversely in a perpendicular direction to the length of the table
ceiling support
it has a single column with rollers at each end, one attached to a ceiling mounted rail and other attached to a floor mounted rail
floor ceiling support system
interventional radiology suits often are equipped with _____
c arm support system
it guards against excessive radiation exposure and electric schock
protective housing
what are those xrays emitted through the window called?
useful beam
the protective housing contains ___ that serves as both an insulator against electric shock and as a thermal cushion to dissipate heat
oil
size of xray tube
30-50 cm long
20 cm in diameter
it is a glass that enable to withstand the tremendous heat generated
pyrex glass
it is the negative side of the xray tube
cathode
it is a coil of wire similar to that in a kitchen toaster, except much smaller
filament
filament is made of thoriated ____
tungsten
it is when an xray tube filament emits electrons when it is heated, when the current through the filament is sufficiently high, the outer electrons of the filament atoms are boiled off and ejected from the filament
thermionic emission
most diagnostic xray tube has two focal spots, one large and one small
dual focus
it is a focal spot that used when better spatial resolution is required that has sfs range from 0.1 to 1mm
small focal spot
it is a focal spot that is used when large body parts are imaged and when other techniques that provide high heat are required and has lfs range from 0.3 to 2mm
large focal spot
two types of anode
stationary anode
rotating anode
it is xray tubes that are used in dental xray imaging system, some portable imaging system and other special purpose units in which high tube current and power are not required
stationary anode
it is a shaft like structure made primarily of a copper and it is a rotating device
rotor
it attaches the rotating target area to the rotor
stem
it is a circular, disk like structure with a slanted or beveled edge
target
it serves as a target for receiving electrons as they move from cathode to anode
target
anode is the positive side, it conducts ______ and radiates ____ and contains the target
anode is the positive side, it conducts electricity and radiates heat and contains the target
target is made up of _____
tungsten
it is an anode that allows the electron beam to interact with as much larger area
rotating anode
stem is made up of _____ because it is poor heat conductor
copper
it is an electromagnetic induction motor that is used to turn the anode
induction motor
it results in an effective focal spot size much less than the actual focal spot size
line focus principle
by angling the target, one makes the effective area of the target much special than the actual area of electron interaction
line focus principle
it is an area that receives beam of electrons from cathode
focal spot
actual xray sources
focal spot
focal spot
when the target angle is made smaller, the effective focal spot size is _____
focal spot
when the target angle is made smaller, the effective focal spot size is also smaller
two focal spot called
biangular target
it is projected on to the patient with the size of the actual focal spot
effective focal spot
it results in smaller effective focal spot and less radiation intensity on the anode side of the xray beam
anode heel effect
low intensity anode, high intensity cathode
anode heel effect
anode heel effect
the smaller the anode angle, the ___ is the heel effect
anode heel effect
the smaller the anode angle, the larger is the heel effect
anode heel effect
the smaller the anode angle, the ___ is the heel effect
anode heel effect
the smaller the anode angle, the larger is the heel effect
positioning the cathode side of the xray tube over the thicker part of the anatomy provides more uniform optical density on the film
anode heel effect
it is when some of the electrons bounce off the focal spot and then land on the other areas of the target causing xrays to be produced from outside the focal spot
extrafocal radiation
extrafocal radiation also called ___
extrafocal radiation also called off focus radiation
it is undesirable, can extend the size of focal spot and can increase patient dose and reduces image contrast
extrafocal radiation
it is undesirable, can extend the size of focal spot and can increase patient dose and reduces image contrast
extrafocal radiation
