Production of X-rays (Lec 3-4) Flashcards
Label the following image:
a) control panel
b) control panel
c) PID
d) tube head
e) X-ray tube
f) power supply (generator)
g) extension arm
The tube head head of the X-ray machine is made up of:
- X-ray tube
- Power supply (generator)
What component of the X-ray machine does this image show?
Control panel
What can be viewed/adjusted on the control panel?
- exposure time
- kVp selector
- mA selector
What type of exposure button do we have on our control panels?
Dead-man type
The _____ light & _____ signal must both be present on the control panel
Indicator light; audible signal
Label the following components of the X-ray tube head
a) x-ray tube
b) step-down transformer
c) step-up transformer
d) cathode -
e) anode +
f) filament circuit
g) tube head seal
h) aluminum discs
i) lead collimator
j) position indicating device (PID)
k) unleaded glass window of x-ray tube
l) insulating oil
m) metal housing of x-ray tube head
Label the following image:
a) tube head
b) PID
Label the following image:
a) x-ray tube
b) yoke
c) oil
d) power supply
e) collimator
f) aiming cylinder
g) x-ray beam
h) aluminum filter
i) power supply
List the important components of the X-ray tube head: (6)
- glass envelope
- insulating oil
- metal housing
- tube window
- aluminum filters
- lead collimator
Label the following image:
a) filament & electron cloud
b) focal spot on tungsten target
c) glass envelope
d) vacuum
e) copper stem
f) anode +
g) useful x-ray beam
h) tube window
i) cathode -
j) electronic focusing cup
The cathode contains:
- filament
- focusing cup
The cathode filament is made of:
Tungsten
What part of the cathode is made of tungsten?
Filament
Source of electrons in the X-ray tube:
cathode filament
Is heated with a low voltage source and emits electrons at a rate proportional to its temperature (thermionic emission):
Cathode filament
The cathode filament is heated with a _____ voltage source, and emits ____ at a rate proportional to _____
low voltage source; electrons; its temperature
The cathode filament emits electrons through:
Thermionic emission
The cathode focusing cup is made of:
Molybdenum
What is the charge of the cathode focusing cup?
Negatively charged
Focuses the electrons into a narrow beam directed to the focal spot (+):
Cathode focusing cup
The cathode focusing cup, focuses the electrons into a _____ directed to the _____
narrow beam; focal spot
What is the charge of the focal spot?
+
The anode contains:
- tungsten target
- copper stem
The tungsten target of the anode functions to:
Transforms the kinetic energy of the colliding electrons into x-ray photons
Functions to transform the kinetic energy of the colliding electrons into x-ray photons:
Anode tungsten target
Highly inefficient: produces 99% heat and 1% x-rays:
Anode tungsten target
Describe the efficiency of the anode tungsten target:
Highly inefficient: produces 99% heat and 1% x-rays
Works as a thermal conductor to remove the heat from the tungsten, avoiding target melting:
Anode copper stem
The anode copper stem works as a ____ to remove heat from the tungsten, avoiding _____
thermal conductor; target melting
Why is tungsten a good target material? (5):
- high atomic number
- high melting point
- high thermal conductivity
- low vapor pressure
- cheap
What does the high atomic number of tungsten allow for?
efficient production of x-rays
Tungsten has a high melting point of ____, what does this allow for?
3422 celcius; to withstand the heat produced
What is the significance of the high thermal conductivity displayed by tungsten?
Allows it to dissipate the heat produced away from the target
The low vapor pressure of tungsten helps to:
maintain vacuum in the tube at high temperatures
Conditions necessary for x-ray production include: (4)
- separation of electrons
- production of high-speed electrons
- concentration of electrons
- sudden stoppage of electron stream
What gives the energy to heat the filament?
The step-down transformer
Low voltage filament current heats the tungsten filament to incandescence with resultant:
Separation of outer shell electrons from tungsten atom (boiling off)
Low voltage filament current heats the tungsten filament to incandescence with resultants separation of outer shell electrons from tungsten atom (boiling off). This separation of electrons is called:
Thermionic emission
label the following image:
a) step-down transformer
b) 6-12 volts
c) focusing cup
d) tungsten filament
e) electron cloud
The ________ is produced between the cathode and anode by applying a high voltage between them
High potential difference
The high potential difference between the cathode and anode contributes to the:
production of high speed electrons
The high potential difference is produced between the cathode and anode by:
applying a high voltage between them
By producing a high potential difference between the cathode and anode, the electrons are accelerated to approximately:
0.5 x the speed of light
What makes the potential difference between the anode and cathode sufficient enough to accelerate the electrons?
Step-up transformer
Label the following image:
a) 6-12 volts
b) 60k-90k volts
c) 60-90 kVp
d) 60k-90k volts
After the electrons are accelerated towards the target what occurs?
Concentration of electrons
The electron beam is focused by the ______ (_____ charge) and directed towards the ____
focusing cup (negative charge); focal spot
In what step is the electron beam focused by the focusing cup (negative charge) and directed towards the focal spot?
Concentration of electrons
Following the concentration of electrons, is the:
sudden stoppage of electron stream
X-rays are produced whenever high-speed electrons are suddenly _____ or brought to a stop when they pass close to the nuclei of a _____, such as _____
decelerated; high Z# absorbing material; Tungsten
What are the four basic steps to the production of an X-ray?
- separation of electrons
- production of high-speed electrons
- concentration of electrons
- sudden stoppage of electron stream
What step of X-ray production is being described below:
Low voltage filament current heats the tungsten filament to incandesce with resultant separation of outer shell electrons from tungsten atom (“boiling off”)
- separation of electrons
What step of X-ray production is being described below:
High potential difference is produced between the cathode and anode by applying high voltage between them
- Production of high-speed electrons
What step of X-ray production is being described below:
Electron beam is focused by the focusing cup (negatively charged) and directed towards the focal spot (positively charged)
- concentration of electrons
What step of X-ray production is being described below:
Upon striking the focal spot in the anode, the electron stream is stopped abruptly, and kinetic energy of the electron stream undergoes conversion to greater than 99% heat and less than 1% of radiation. Copper stem removes the heat from the tungsten
- sudden stoppage of electron stream
The low voltage supply for the separation of electrons comes from the:
Step-down transformer
During the separation of electrons (step 1) the low voltage filament current, heats the tungsten filament to incandesce with resultant:
Separation of outer shell electrons from tungsten atom (“boiling off”)
During the separation of electrons (step 1) the low voltage filament current, heat tungsten filament to incandesce with resultant separation of outer shell electrons from tungsten atom (“boiling off”) this separation is called:
Thermionic emission
The separation of electrons is accomplished through:
Thermionic emission
During the production of high-speed electrons (step 2) the high potential difference is produced between:
The cathode and the anode
During the production high-speed electrons (step 2) the high potential difference produced between the cathode and anode occurs by:
Applying high voltage between them
During the concentration of electrons (step 3) the electron beam is focused by the _____
Focusing cup
Describe the charge of the focusing cup:
Negatively charged
During the concentration of electrons (step 3) the electron beam is focused by the focusing cup (negatively charged) and directed towards the:
Focal spot (positively charged)
During the sudden stoppage of electron stream (step 4) upon striking the focal spot in the anode, the electron stream is:
Stropped abruptly