Chapter 6: The x-ray tube

Physics final study guide
source of electrons, target, high-voltage, and vacuum
What are the 4 things needed to produce x-rays?
What is the source of electrons in the x-ray tube?
What is the x-ray tube target called?
filament, focusing cup, and associated wiring
What are the three parts of the cathode assembly?
What is the focusing cup generally made out of?
focal spots
What are the associated wiring in the cathode assembly?
thoirated tungsten
The filament is a coil of ___ ___.
recorded detail
The filament length and width impact what?
high melting point and difficult to vaporize
What are the two main reasons tungsten is selected as the filament material?
rhenium and molybdenum
What are two other good choices, besides tungsten, for the filament material?
dual focus
What is the term used to describe the type of x-ray tubes that have two focal spots, one large and the other small, as well as two filaments, one large and the other small.
thermionic emission
What is the process of electrons being released from the filament as it is heated called?
tube arcing
What is the name of the tube failure where vaporized tungsten is collected on the envelope?
filament breakage
What is the name of the tube failure that occurs from "boost and hold"?
space charge effect
The negatively charged focusing cub compresses the thermionic cloud. This process is known as what?
biased focusing cup
A ___ ____ ____ maintains the focusing cup at a more negative voltage than the filament (used in mammography).
saturation current
What is the filament phenomenon that has been achieved when there are no further thermionic electrons to be driven toward the anode?
target surface, conducts high voltage, and primary thermal conductor
What are the three functions of the anode assembly?
anode, stator, and rotor
What are the 3 components of the anode?
stationary and rotating
What are the 2 different types of anode?
tungsten-rhenium alloy
Rotating anodes are composed of _______ ____ because it has a high z#, melting point, and heat-conducting ability.
anode layering
What assists with heat loading for the anode?
molybdenum or graphite
With a layered anode, the tunsten is usually backed with what?
What is the target material used for mammographic equipment?
Mammographic equipment requires (lower / higher) energy photons?
What material is the tube window made out of for mammographic equipment?
warm-up procedure
What gradually warms up the anode and helps maintain the vacuum?
Warming up the tube prevents what from occuring?
target area
What is the portion of the anode that the electron steam contacts?
focal track
What is the circular path that is impacted by the electron beam for a rotating anode?
rotating anode
What type of anode dissipates heat more effectively?
Which focal spot is the area on the anode that is impacted?
Which focal spot is the area on the IR that results?
Line focus principle
What is the relationship between the actual and effective focal spot called?
actual focal spot and target angle
The effective focal spot is controlled by what two things?
X-rays are emitted _____.
smaller, better
A smaller target angle has a ____ effective focal spot and ____ detail.
What is the distance between the IR and X-ray tube?
What is the distance between the x-ray tube and object?
What is the distance between the object and image receptor?
large, small
A ____ IR and ____ SID will show a noticible effect from the anode heel effect.
The anode heel effect states that more x-rays escape on which side?
Move of a target angle has (more / less) impact with the anode heel effect.
The stator is a bank of _____ located outside the envelope?
The rotor is made of what material?
What turns the staor when energized?
ball bearings
What part of the rotor reduce friction or heat?
pyrex glass or metal
What is the envelop made out of that is ease to mold and easy for x-rays to pass through?
window and vacuum
The envelope contains what two important parts of the x-ray tube?
protective housing
What controls leakage and scatter radiation?
The protective housing isolates (high / low) voltages.
lead-lined cast steel
The protective housing is made of what?
100 mR/hour
The leakage radiation limit for the protective housing is ______ at 1 meter?
dielectric oil
What surrounds the envelope and is used to insulate, promote cooling, and is sometimes circulated trhough a heat exchanger?
tube rating chart
What chart or graph is used to determine how much heat or exposure a tube can take?
anode cooling curves
What chart or graph is used to determine how long to wait until another exposure can be taken?
kVp x mA x time x rectification constant
How do you determine the heat units?
What is the rectification constant for a single phase generator?
What is the rectification constant for a three phase generator?
What is the rectification constant for a HF generator?