Production of X-rays- Lecture 3 & 4 Flashcards
Label the following image:
A) Control Panel
B) Control Panel
C) PID
D) Tubehead
E) X-ray Tube
F) Power Supply (Generator)
G) Extension Arm
The tube 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 panel?
Dead-man type
The ____ light and ____ 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) film & 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?
the 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 electron 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?
positive
The anode contains:
- Tungsten target
- Copper stem
The tungsten target of the anode functions to:
transform 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 that 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 temps
Conditions necessary for x-ray production include: (4)
- separation of electrons
- production of high speed electrons
- concentration of electrons
- sudden stoppage of electron steam
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 resultant separation of outer shell electrons from the 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:
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:
0.5x 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 electrons are accelerated toward 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 steam
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 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% 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 heats the 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 of 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:
stopped abruptly
During the sudden stoppage of electron stream (step 4), upon striking the focal spot in the anode, the electron stream is stopped abruptly and the kinetic energy of the electron stream undergoes conversion to:
greater than 99% heat and less than 1% radiation
During the sudden stoppage of electron stream (step 4), what removes the heat from the tungsten?
copper stem
During the sudden stoppage of electron stream (step 4), the copper stem removes the heat from:
tungsten
Label the cathode and anode:
A) Cathode
B) Anode
What are the two main parts of the cathode?
- filament
- focusing cup
The filament of the cathode is made of:
tungsen
The filament of the cathode is the:
source of electrons
The filament of the cathode is heated with:
a low voltage source
The filament of the cathode is heated with a low voltage source and emits:
electrons at a rate proportional to its temperature
The filament of the cathode is heated with a low voltage source and emits electrons at a rate proportional to its temperature. This is known as;
thermionic emission
The focusing cup of the cathode is made of:
molybdenum
What is the charge of the focusing cup of the cathode?
negatively charged
Focuses electrons into a narrow beam directed to the focal spot (+):
focusing cup of cathode
The focusing cup of the cathode focuses the electrons into a narrow beam directed to the:
focal spot (+)
What are the two main parts of the anode?
- tungsten target
- copper stem
The tungsten target of the anode is responsible for:
transforming the kinetic energy of the colliding electrons into x-ray photons
Describe the efficiency of the tungsten target at transforming the kinetic energy of the colliding electrons into x-ray photons:
highly inefficient: produces 99% heat and 1% x-rays
Where are x-rays produced?
The tungsten target of the anode
Why is tungsten a good target material? (Anode) (4)
- high atomic number
- high melting point
- high thermal conductivity
- low vapor pressure
What is the function of the copper stem in the anode?
works as a thermal conductor to remove the heat from the tungsten avoiding target melting/ overheating
The copper stem in the anode works as a thermal conductor to remove heat from the tungsten avoiding:
target melting/overheating
What are the two ways to prevent overheating of the tungsten target?
stationary anode and rotating anode
Angling the target to achieve a smaller effective focal spot than the actual focal spot. Results in a sharper radiographic image
stationary anode
What type of image is the result of a stationary anode:
shaper radiographic image
What principle is described by having a stationary anode:
line focus principle
Projection of the focal spot perpendicular to the target:
actual focal spot
Projection of the focal spot perpendicular to the electron beam:
effective focal spot
The effective focal spot is always ____ than the actual focal spot
smaller
What is the purpose of a transformer?
Electromagnetic device that either increases or decreases the voltage in a circuit
Electromagnetic device that either increases or decreases the voltage in a circuit
transformer
What are the three types of transformers?
- step-down transformer (filament transformer)
- step-up transformer (high voltage)
- autotransformer
What transformer is used to heat the filament?
step-down transformer
Converts 110 or 220 volts to 3-5 volts:
step-down transformer
The step-down transformer converts ____ volts to ____ volts
110 or 220 volts to 3-5 volts
What transformer is involved in the low voltage circuit?
step-down transformer
The step-down transformer is regulated by the:
mA switch
What does increasing mA do to the step-down transformer?
increasing mA increases the NUMBER of electrons emitted
What is powered by the step-down transformer?
Cathode
What transformer converts 110 or 220 volts to 60k-100k volts?
step-up transformer
Why does the step-up transformer increase the voltage so substantially?
to move electrons across the tube (high-voltage circuit)
What transformer is involved in the high-voltage circuit?
step-up transformer
The step-up transformer is regulated by:
kVp setting
What does increasing the kVp setting do to the step-up transformer?
increases the ENERGY of electrons traveling from cathode to anode
The ___ is powered by the step-up transformer
anode
Each half cycle (1/120 of a second) the anode is positive and attracts the electrons from the cathode
x-radiation is produced
Each alternate half cycle (1/120 of a second) the anode is negative and therefore there is no attraction for electrons
no x-radiation is produced
X-radiation is produced when the anode is:
positive
No x-radiation is produced when the anode is:
negative
Wave of periods of producing and not producing x-rays:
alternating current
The cathode and anode alternate between positive and negative which causes x-rays to be produced only half of the time
alternating current
During an alternating current, x-rays are produced:
half of the time
During an alternating current, the cathode and anode alternate between:
positive and negative
Current is always running in the same direction and always producing x-rays:
direct current
Direct current keeps the:
cathode negative and anode positive
During a direct current, the current is always running in ____ and always producing ___.
same direction; x-rays
Functions to decrease radiation dose and exposure time:
direct current/constant potential
Direct current/constant potential function too:
decrease radiation dose and exposure time
Diamond that redirects alternating pathways/non-producing x-rays from the filament to the target anode regardless of + or -:
rectifier
The rectifier (diamond) redirects alternating pathway/ non-producing x-rays from the filament to the target anode regardless of:
+ or - charge
Flow of electrons through an electrical conductor:
electricity
Amount of electrons flowing through a conductor per second. Measured in amperes (A)
current
Path of electrical current:
circuit
Difference in electrical potential energy between two points in an electrical circuit. Measured in volts (V)
Voltage (potential difference)
Current is measured in:
amperes (A)
Voltage is measured in:
Volts (V)
Low voltage filament current heats the tungsten filament to incandescence with resultant separation n of outer shell electrons from tungsten atom (“boiling off”):
thermionic emission
Controls heating of the filament. This controls the number of electrons emitted and number of x-rays produced:
mA
Controls the acceleration/energy of electrons from cathode to anode:
kV
How does mA effect x-ray production?
controls heating of the filament which controls the number of electrons emitted and the number of x-rays produced
How does kVp effect x-ray production?
Controls the acceleration/energy of electrons from cathode to anode
The voltage difference between the filament/cathode and target/anode:
kVp
Bremsstrahlung x-ray production describes:
electron to nucleus interaction
High velocity electrons (directed towards target) either slow down or stop when they come close to the nucleus of the atoms and part of their energy is transferred as x-rays:
Bremsstrahlung x-ray production
Bremsstrahlung x-ray production is also known as:
breaking radiation
According to Bremsstrahlung x-ray production, the high velocity electrons (directed towards the target) either ____ or ____ when they come close to the nucleus of the atoms and part of their energy is transferred as ____.
slow down; stop; x-rays
In Bremmsstrahlung x-ray production, all electrons do not attain the same ____.
velocity
In Bremmsstrahlung x-ray production, all electrons do not attain the same velocity, why is this?
Because of wide distribution of wavelengths (heterogeneous)
What happens to electrons when they interact with tungsten atoms in Bremsstrahlung x-ray production?
electrons lose their energies in random fashions
In Bremsstrahlung x-ray production, when an electron has a head on collision with the nucleus, this causes:
electron to stop, producing a maximum energy photon
Bremsstrahlung spectrum is a ____ spectrum
continuous emission spectrum
Bremsstrahlung spectrum is a continuous emission spectrum because bremsstrahlung radiation:
- increases with increasing voltage and atomic number of the target
- different energies of of x-rays are emitted based on where electron hits the nucleus
Bremsstrahlung spectrum is a continuous emission spectrum because bremsstrahlung radiation _____ with increasing voltage and atomic number of the target
increases
Bremsstrahlung spectrum is a continuous emission spectrum because different energies of x-rays are emitted based on:
where electron hits the nucleus
In Bremsstrahlung spectrum, maximum energy occurs when:
electron hits nucleus and is stopped completely
The process of characteristic x-ray production involves ____ interaction
electron to electron
In _____ x-ray production, a few electrons interact with the tungsten target orbital electron, imparting enough energy to ionize the tungsten. This removes an electron from the orbit and immediately electron is filled from outer shell and energy is emitted
characteristic x-ray production
In characteristic x-ray production, the energy emitted by the electron is equivalent to:
the difference in the binding energies of the two shells/ orbitals
Characteristic x-ray production:
L to K transition =
M to K transition =
L to K = 57,400 eV
M to K= 66,700 eV
Explain why characteristic radiation is called discrete radiation:
discrete energy is imparted to the newly formed radiation which is “characteristic” of the atom type and orbital from which came
_____ % of the diagnostic x-ray beam is characteristic radiation while ____% is Bremsstrahlung radiation.
30%; 70%
The majority of the diagnostic x-ray beam is ___ radiation
Bremsstrahlung (70%)
A rotating anode allows heat at the focal spot to spread out over:
A large surface area (dark band)
What type of anode is used in medical devices?
rotating anode
Determines the amount of time the high voltage circuit is applied across the X-ray tube (amount of time the x-rays are produced)
exposure timer
Delay of 1/2 second to heat the filament:
time-delay circuit
Actual time of exposure:
timing circuit
What three controls are on the control panel?
- kV (kilovoltage)
- mA (milliamperage)
- Exposure time
Controls the acceleration of the electrons from the cathode to the anode:
kV (kilovoltage)
Controls heating of the filament:
mA (miliamperage)
Controls the time in which x-rays are produced:
exposure time
