X-ray Production Flashcards
What are two types of x-rays?
- Brems
2. Characteristic
How are Brems produced?
Electrons being slowed down as it passes the nucleus
What is a space charge?
Electron cloud that surrounds the filament
What do the speed of the electrons depend on?
kVp
What are characteristic x-rays?
X-rays emitted when an outer shell electron fills an inner shell void
How much of the primary beam are Characteristic x-rays?
10%
What is the binding energy of the K shell?
69.5
How much of the kinetic energy of projectile electrons are converted to heat?
99%
What type of Characteristic x-rays are useful for imaging?
K shell characteristic x-rays
The incident (projectile) electron must have an energy level (KeV)…
Close to the binding energy of the k shell
Where does the heat come from?
Outer shell electrons from the target atoms
What is the wave theory?
X-rays exist as vibrating electric charges or waves
When were the 1st x-rays made?
Nov 8th, 1895
If wavelength goes up, then frequency goes…
Down
Filters harden the beam via the process of…
The photo electric effect
What is electromagnetic radiation?
The transport of energy through space as a combination of electric and magnetic fields
All members of the electromagnetic spectrum including x-rays travel at what speed?
The speed of light (186,000 mps)
Wavelength is usually measured from ____ to ____
Crest to crest
-The top of one wave to the top of the other
In what ways do x-rays differ from other members of the EM spectrum?
- Frequency
- Energy
- Wavelength
- Penetrating ability
What is a wavelength?
The distance between any two successive points on a wave
What is frequency?
The number of waves per second
What is the unit of frequency?
Hertz (Hz)
What does Bremsstrahlung mean?
Breaking or slowing radiation
Brems radiation makes up ____% of the primary beam within the 80-100 kVp range?
90%
Characteristic radiation makes up ___% of the primary beam in the 80-100 kVp range.
10%
What is a positive ion?
An atom left behind after electron is ejected
How much useful characteristic radiation is produced below 69 kVp within a tungsten target?
None
How do you increase the probability of characteristic radiation forming?
- Incident electrons must have a keV of 69 plus a little
- Target should have a high atomic #
What is a photoelectron (negative ion?)
A k-shell electron that was ejected
How many different x-ray energies does the characteristic x-ray emission spectrum contain
15
What are the (4) reasons the primary beam is polyenergetic?
- The fluctuating kv applied to the tube
- The combination of Brems and Characteristic radiation
- The multiple electron interactions with the target atoms
- The product of off focus radiation
What is the atomic # of Tungsten?
74
What is wavelength represented by?
Lambda= λ
What are the units of a wavelength? (not the lambda symbol)
Angstrom= Å
The primary beam is _______.
Polyenergetic
How fast do x-rays travel?
At the speed of light
What is an angstrom equal to?
1/ 100 millionth of a cm
The useful range of an Angstrom in diagnostic radiation is…
0.1- 0.5 Angstroms
As you go from left to right on the electromagnetic spectrum, everything gets higher except what?
The wavelength
Frequency- Highest
Energy- Highest
Wavelength- Shorter
Penetration- Most
What will cause x-rays to go from a higher wavelength to a shorter wavelength?
- Increase the kVp
- The technique
What are the (2) types of x-rays produced inside the x-ray tube?
- Brems
2. Characteristic
Frequency is represented by?
NU (the greek letter v)
What are the different frequencies of the electromagnetic spectrum?
- Radio
- Microwaves
- Infrared
- Visible
- Ultraviolet
- X-rays
- Gamma rays
- Cosmic rays
What type of x-rays are produced at varying amounts of energy?
Brems
Radiation that is Bremsstrahlung is Heterogeneous or _______.
Polyenergetic
X-ray Brems photons _____ in energy levels
Vary
How fast do electrons travel?
Half the speed of light
As electrons pass the nucleus what do they do?
Brake or slow down
As an electron passes the nucleus it slows down. What happens to the kinetic energy it looses?
It’s released as Electromagnetic energy in the form of an x-ray photon
What determines the energy of the photon?
The kVp (how fast it’s going) and how close it comes to the nucleus
The projectile electrons come from the…
Cathode
In Brems radiation, does the projectile electron interact with other electrons within the atom?
No
What is the number of electrons coming from the cathode to the anode determined by?
The mA
What does the energy of the resulting x-ray photon depend on?
- The distance of the projectile electron from the nucleus of the target atom
- The amount of kinetic energy lost by the incident electron
What are the vast majority of x-ray photons coming out of the tube?
Brem’s photons
Energies of the resulting x-ray photon can range from ___ keV to the keV equivalent of the kVp
0
The maximum amount of Brems photons will always have an energy equivlaent to…
1/3 of the kVp
What happens when an electron is ejected out of the atom?
- A hole is left leaving it unstable
- An electron from a higher shell then moves down to fill it
Energy of the resultant x-ray is characteristic of the _____ element and the ____ involved in it’s production
Target/ Shells
While completing a hand x-ray, what type of x-rays are being used?
Brems
How do photons slow down enough to interact with k-shell electrons?
By going through Brems interactions
What shell has the most potential energy?
- The outer shells
- They have the least binding energy enabling them to move easier
What are the binding energies of the different shells for tungsten?
K- 69 L- 12 M- 3 N- 1 O- 0.1 P- 0
What happens when an outer shell electron fills the vacancy of an inner shell electron?
A Characteristic photon is created
How do you determine the energy of a characteristic photon?
By subtracting the binding energy of the two shells. The shell it came from, from the shell it replaced
When an outer shell electron drops down and fills a vacancy in the K shell, is the characteristic radiation useful or not?
- Yes
- The energy will be determined by subtracting the two binding energies (between 57- 69 keV)
When shells other than the k-shell are knocked out, is the characteristic radiation produced useful or not?
It is not. It probably won’t make it out of the tube
Using an 80 kVp exposure, what is the average energy of the maximum number of Brems photons?
1/3 of 80= 27
If an incident electron has energy just over 69 and interacts with a k-shell electron what type of radiation is produced?
Characteristic radiation
What (2) things make up an ion pair?
- Photoelectron (negative ion)
2. Positive ion
X-ray production is mostly ______.
Heat
