X-Radiation Flashcards
Penetrating electromagnetic radiation having wavelengths shorter than visible light which are produced by bombarding a target with high speed electrons
X-rays
12 properties of x-rays
- Invisible
- No mass/ weight
- No charge
- Travels at the speed of light
- Travels in a straight line and can be deflected or scattered
- Cannot be focused to a point; always diverge from a point
- Capable of ionization
- Can cause certain substances to fluorescence or emit radiation
- Absorbed by matter, depends on the wavelength and atomic structure of matter
- Can penetrate solids, liquids, and gases
- Can produce an image in a photographic file
- Can cause biological changes in living things
What occurs at the subatomic level of production of x-rays?
Generation, emission, and absorption
3 things needed to generate x-rays
- Electrons
- A way to accelerate the electrons
- A target for the accelerated electrons to interact with
3 parts of the x-ray machine
- X-ray tube head
- Power supply
- Timer
This is the tungsten filament inside a molybdenum cup in the x-ray tube head
Cathode (-)
This is the tungsten target embedded in a copper system in the x-ray tube head
Anode (+)
This is the two types of transformers found beside the x-ray tube
Power supply
What are the two types of transformers under power supply?
a. Step-down
b. Step-up
What circuit under power supply supplies the x-ray tube?
Low-voltage circuit (filament circuit)
What circuit under power supply connects both ends of the x-ray tube?
High-voltage circuit
This is built-in with the high voltage circuit to control the duration of x-ray exposure
Timer
The exposure time is?
0.5-1 sec
This works with the deadman switch
TImer
This states that energy is neither produced or destroyed
Law of conservation of energy
Generation of x-rays
Electrical energy → Step-down transformer → Thermionic emission
This is the primary source of x-ray photons
Bremsstrahlung radiation
This is when high speed electrons from the cathode hits the nucleus of the tungsten atom producing a photon of maximal energy or electron passes very near the nucleus, so part of it gets deflected with a lower energy electron
Bremsstrahlung radiation
Instead of passing by the nucleus, it hits one of the orbiting electrons
Characteristic radiation
If the electron has sufficient energy, it will eject an electron from that tungsten atom, creating a vacancy that has to be filled up by one of the electrons from the outer shell and will create the x-ray
Characteristic radiation
Following the ionization or excitation of the tungsten atoms by the bombarding electrons, the orbiting tungsten electrons rearrange themselves to return the atom to the neutral or ground state
Characteristic spectrum
The penetrating x-ray beam that is produced at the target of the anode
Primary radiation
X-radiation created when the primary beam interacts with matter
Secondary radiation
A form of secondary radiation, the result of an x-ray that has been deflected from its path by the interaction with matter
Scatter radiation
Change in direction of a photon with or without a loss of energy
Scattering
Deposition of energy, i.e. removal of energy from the beam
Absorption
This is the reduction in the intensity of the main x-ray beam caused by absorption and scattering
Attenuation
This is absorption + scattering
Attenuation
Removal of an electron from a neutral atom producing a negative ion and a positive ion
Ionization
Photons ionize the absorber atoms, and there is transfer of deposition of energy
Absorption
A photon collides with a bound electron in one of the inner shells
Photoelectric absorption (30%)
Four main interactions at the atomic level
- Unmodified or Rayleigh scattering
- Photoelectric effect
- Compton effect
- Pair production
Pure scatter
Unmodified or Rayleigh scattering
Pure absorption
Photoelectric effect and pair production
Scatter and absorption
Compton effect
Responsible for producing densities on the film and make dental radiography possible
Photons
A pure absorption interaction predominating with low-energy photons
Absorption of energy and photoelectric effect
What is it called when in an inner-shell electron is ejected with considerable energy?
Photoelectron
An absorption and scattering process predominating with higher-energy photon
Compton effect
What is it called when an outer-shell electron is ejected with some of the energy of the incoming photon?
Compton recoil electron
An x-ray photon that has its path altered by matter
Coherent scatter
