what controls the # of electrons produced by the filament
cathode
process of changing alternating current to a direct current
recitification
what reduces the x-ray machine input voltage from 110-220V to 10 V to prevent burnout of the cathode filament
step-down transformer
what controls the length of exposure
timer switch
AKA self-rectifiers
valve tubes
what allows the flow of electrons in one direction only
valve tubes
what is the peak energy of the x-rays that determines the quality called
kilovoltage (kVp)
what part of the x-ray tube consists of a coiled wire tungsten filament that emits electrons when heated
actual focal spot
what is the small area of the target were electrons collide on the anode
focal spot
the ____ is made up of molybdenum because it has a high melting point and is a poor heat conductor
focusing cup
___ acts as a conductor of heat and draws the heat away from the tungsten target
oil
what type of anode is found in dental and small portable radio graphic units
stationary
what type of anode continually provides a cooler surface for the electron stream to hit
rotating
restricting device used to control the size of the primary x-ray beam
collimator
what are the 4 factors that an x-ray tube rating is based upon
focal spot size, target angle, anode speed, electrical current
what unit is the x-ray tubing rating expressed in
kilowatts
stationary anode focal spot size
small
using a high kVp and a low mAs helps prevent
damage to anode
what noise happens when anode bearing fails
grinding metal/ no noise
how far away should the radiographer be from the machine
6 feet
what increases the incoming voltage of 110-220 V to 1000 V
step up transformer
a decrease of intensity on the anode side of x-ray beam due to angle
heel effect
creates a partial shadow of the object being imaged
halo effect
what size focal spot is ideal and why
small; greater detail
what is the #1 cause of x-ray tube failure
cathode failure
how can cathode failure be avoided
let the machine heat up
what is gassy tube
glass envelope damage; occurs when air gets into glass tube
the line-voltage compensator is associated with the ___ and is automatic in most new machines
autotransformer
what is the maximum electrical and thermal rating for portable x-ray units
60-90 kVp
what is the maximum electrical and thermal rating for table top x-ray units
40-120 kVp
coning aka
collimation
due to heel effect, what part of the animal should be placed toward the cathode
large size
what occurs during 1st phase of the exposure button
filament heats and anode spins
what occurs during 2nd phase of the exposure button
radiograph is created
__ kVp and __mAs techniques should be used as often as possible to prevent anode damage
high;low
what is the glass vacuum tube that contains the cathode and the anode of the x-ray tube
glass envelope
metal deposits on the inner wall of the envelope that attract electrons from the cathode
arcing
control panel of the machine
console
low energy circuit, when heated, releases electrons from their orbits
filiment
amount of electical energy being applied
milliamperage
creates constant electrical potential across the tube
full wave rectification
converts alternating to direct current
half wave rectification
what is used to focus the beam
lead shutters
recessed area where the filament lies, directing the electrons toward the anode
focusing cup
effect of making the focal spot appear smaller when viewed from the position of the film
line focus principle
