Cooling Charts are available for the
Tube Housing and Anode
Both A and B are correct
Most x-ray tube target angles range between
7-18 degrees
Of all the energy involved in x-ray production, 99% is converted to
Heat
The melting point of tungsten is
3400 degrees C
Which of the following occurs first during x-ray production
voltage level is adjusted at autotransformer
X-ray tubes with a stationary anode design may be found today
in old tubes designs and dental x-ray units or those that require very small exposure techniques.
The positive end of the x-ray tube is the
anode
Electrons from the cathode that do not produce x-rays will
turn into heat?
To keep the electrons together, the focusing cup
forces electrons together with its strong negative charge
The electrons in the tube current travel
half the speed of light
The protective tube housing helps to
all of these are correct
The filament is primarily made of
tungsten
The portion of the induction motor that is outside the tube enclosure is the
stator
With a rotating anode, the focal spot becomes a focal
track
Which of the following occurs last during x-ray production
The electrons flow from cathode to anode, it is a continuation of the flow of electricity through the x-ray circuit
Which of the following practices extend the tube life
all of these are correct
The primary advantage of a rotating anode is that it allows
greater heat capacity at the anode
The target window is usually approximately
5cm squared
Molybdenum is found in the ________ of the rotating anode
both A and B are correct
The cloud of electrons produced through thermionic emission is more accurately called a(n)
space charge
Heat from x-ray production is removed through conduction by the heat traveling from
heat materials
The negative end of the x-ray tube is the
cathode
An x-ray tube with two filaments is called a
dual-focus tube
The advantages to using a larger actual focal spot is
heat dissipation, the smaller the stream the greater the heat generated in a small area.
Pitting of the anode is the result of
extended use
To allow x-rays to leave the tube, the glass or metal enclosure in the area of the target window is
made thinner
Glass enclosures are typically made of borosilicate glass (Pyrex) because
it is very heat-resistent
Based on the anode heel effect, an image taken at 40 inches SID may demonstrate
decreased exposure toward the anode end of the beam
The focusing cup is able to keep the electrons together because
opposites attract
Tube rating charts
all of these are correct
The size of the actual focal spot depends on
the size of the cathode filament being used
The induction motor turns the rotor of a specialty tube _____ revolution per minute
10,000
An issue with using glass envelopes is that they
cause arcing and damage, vaporized tungsten from the filament deposits on the inside of the glass.
The space charge effect describes
self-limiting factor, large potential difference to give kinetic energy to the filament electrons, a vehicle on which kinetic energy can ride, and a place for interaction
The rotating anode design uses a disc whose core is made of
molybdenum
Molybdenum
great at conducting heat, strong and lightweight
One of the reasons the molybdenum is used in rotating anodes is because it is
low thermal conductivity, slows migration of heat into the rotor bearings minimizing heat damage, lightweight and strong, easy to rotate
After lengthy exposures, the x-ray tube on a mobile fluroscopic unit may
be very hot
Which of the following occurs first during x-ray production
The voltage from the autotransformer passes to the step-up transformer.
The filaments are part of the
filament circuit
Heat from x-ray production is removed through convection by the heat traveling from
the tube to the room by cooling fans
The two types of anode designs are stationary and
rotating
If the anode angle becomes too small, which of the following may result
all of these are correct
Arcing
is a problem associated with glass envelopes
Copper can be found _____ of the rotating anode
in the shaft
The cathode includes the
both B and C are correct
Part of the useful x-ray beam gets absorbed in the anode when
the anode angle is too small
The stationary anode includes an are of tungsten embedded in
copper rod
For the covering of the rotating anode disc, _______ may be added to tungsten to increase thermal capacity
Rhenium
The formula kvp x mA x s x c is used to calculate
heat units
The area of the envelope where x-rays should exit the tube is the
window
The anode serves as a(n)
all of these are correct
The best situation is to have a _____ actual focal spot and a _______ effective focal spot.
large; small
Tungsten is used to coat the anode disc because it
has a high atomic number
The cathode
all of these are correct
The tube rating chart plots mAs, kvp, and
exposure time
The anode includes the
both A and B are correct
The primary purpose of the glass or metal exposure is to
maintain a vacuum
The advantage to using a small effective focal spot is
the image is sharper
When the exposure switch at the operating console is first depressed
Some of the electricity is diverted to the induction motor of the x-ray tube to bring the rotor up to speed. Induction motor turns the anode at 3400 rpm
The stationary anode includes an area of _______ embedded in a copper rod
tungsten
The most common x-ray tube target angle is
12 degrees
Tungsten is used to coat the anode disc because it
conducts heat well
The rotor is made of
iron core (iron bars embedded in the copper shaft)
Which of the following practices extend tube life
press the prep and exposure switches at almost the same time
The motor that turns the anode operates through
mutual induction
The focusing cup is made of
nickel
The effective focal spot is the
size of origin of the x-ray beam as seen from below the tube
By regulation, x-ray tube leakage radiation can be no more than
100 mR per hour
The primary disadvantage to the stationary anode is that it
heats up too quickly during x-ray production
The focusing cup is part of the
secondary circuit
The atomic number of tungsten is
74
Heat from x-ray production is removed through radiation by the heat traveling from
the tube to the oil bath
How many heat units are produced with five consecutive exposures using a three-phase, 12-pulse x-ray unit, 85 kvp, and 20 mAs?
11,985 HU
Of all the energy involved in x-ray production, _______ is converted to x-ray energy.
1%
Tungsten is used to coat the anode disc because it
has a high melting point
The protective tube housing is lined with
metal structure that serves as an electrical insulator and thermal cushion for the tube itself; lead lined
There is a small amount of _____ added to the filament to increase thermionic emission.
thorium
The purpose of the focusing cup is to
keep the electrons together
In terms of the x-ray tube, envelope is another name for the
glass or metal enclosure
The induction motor turns the rotor of a standard x-ray tube ______ revolutions per minute
3400
Thermionic emission is
heating the filament until electrons are boiled off
Excessive heat may be transferred to the rotor bearings, resulting in
the anode rotating unevenly
The rotor is found
inside the envelope
The ______ is used to calculate the length of time needed between exposures so that the tube's heat loading capacity is not exceeded
cooling chart
The relationship between the actual focal spot size, effective focal spot size, and anode target angle is called
the line-focus principle
The smaller the anode angle
the smaller the effective focal spot
Copper is used in the rotating anode because
it is an excellent conductor
With a rotating anode, the focal spot becomes a focal
track
In terms of the x-ray tube, envelope is another name for the
glass or metal enclosure
The portion of the induction motor that is outside the tube enclosure is the
stator
Using very long exposures can lead to tube damage or failure:
True or False
True
By regulation, x-ray tube leakage radiation can be no more than:
100 mR per hour
The anode includes the
both A and B are correct
An x-ray tube with two filaments is called a
dual-focus tube
To take advantage of the anode heel effect, the thinner part of the anatomy being imaged should be placed under the cathode end of the tube.
True or False
False
Which of the following practices extend tube life?
Press the prep and exposure switches at almost the same time
The stator is made up of electromagnets.
True or False
True
How many heat units are produced with five consecutive exposures using a three-phase, 12-pulse x-ray unit; 85 kVp, and 20 mAs?
11,985
The cathode
all of these are correct
To take advantage of the anode heel effect, the thicker part of the anatomy being imaged should be placed under the anode end of the tube.
True or False
False
The primary purpose of the glass or metal enclosure is to
maintain a vacuum
The rotating anode design uses a disc whose core is made of
molybdenum
The primary disadvantage to the stationary anode is that it
heats up too quickly during x-ray production
Based on the anode heel effect, an image taken at 40 inches SID may demonstrate
decreased exposure toward the anode end of the beam
The tube rating chart plots mA, kVp, and
exposure time
The cloud of electrons produced through thermionic emission is more accurately called a
space charge
The motor that turns the anode operates through
mutual induction
Heat from x-ray production is removed through convection by the heat traveling from
cooling fans
The two types of anode designs are stationary and
rotating
The effective focal spot is smaller than the actual focal spot because the face of the anode is angled.
True or False
True
To allow x-rays to leave the tube, the glass or metal enclosure in the are of the target window is
made thinner
The filaments are part of the
filament circuit
For the covering of the rotating anode disc, ______ may be added to tungsten to increase thermal capacity.
rhenium
The target window is usually approximately
5 cm squared
The rotor is supplied with electric current through the x-ray circuit.
True or False
False
Which of the following occurs first during x-ray production?
Voltage level is adjusted at autotransformer
How many heat units are produced with an exposure using a single phase x-ray unit, 75 kVp, and 50 mAs?
3750 HU
Prepping the rotor but not making an exposure on a regular basis is unrelated to tube damage or failure.
True or False
False
When electrons strike the anode target, they all produce x-rays.
True or False
False
Molybdenum is found in the ________ of the rotating anode.
both A and B are correct
Arcing:
is a problem associated with glass envelopes
The ________ is used to calculate the length of time needed between exposures so that the tube's heat loading capacity is not exceeded.
cooling chart
The most common x-ray tube target angle is:
12 degrees
An issue with using glass envelopes is that they:
allow vaporized tungsten to coat the inside of the glass
The stationary anode includes an area of _______ embedded in a copper rod
tungsten (button)
The oil surrounding the x-ray tube serves only to provide electrical insulation.
True of False
False
Copper is used in the rotating anode because
it is an excellent conductor
The positive end of the x-ray tube is the
anode
Many newer x-ray units do not need the radiographer to go through a warm-up procedure.
True or False
True
The purpose of the focusing cup is to
keep electrons together