X-ray Production II Flashcards
How efficient is the kinetic energy of the projectile electron in an x-ray tube?
About 1% efficient in the production of x-rays
The shift of the characteristic x-ray spectrum to higher energy occurs because of what?
An increase in target atomic number
How are useful characteristic x-rays produced in tungsten?
By the removal of k-shell electrons
What is produced when the projectile electron excites an outer shell electron?
Heat
The energy of characteristic x-rays increases with increasing the what?
Atomic number of target material
When are x-rays produced?
When the projectile electrons interact with target atoms
Characteristic x-rays are characteristic of the target _____.
Z# (atomic number)
When a tungsten targeted x-ray tube is operated at 68 kVp, can K shell characteristic x-rays be produced?
No
When characteristic x-rays are produced, what is the energy characteristic of?
The atomic number of the target
What is the kinetic energy of a projectile electron measured in?
Joules
The efficiency of x-ray production is ________ of tube current.
Independent
What is Brems radiation produced by?
The conversion of projectile electron kinetic energy to electromagnetic energy
When a Brems x-ray is produced, a projectile electron ____ its energy
Loses
In Brems x-ray production, the projectile electron is from the ______.
Cathode
If an average radiographic technique is used, most x-rays are ______.
Brems
Brems x-rays are produced only at:
Energies up to the projectile electron energy
What would happen if a radiographic technique in a tungsten target at 60 kVp 80 mAs is changed to 80 kVp @ 80 mAs?
The number of x-rays produced increases
In a tungsten targeted x-ray tube, are there more Brems x-rays or characteristic x-rays?
Brems
When a Brems x-ray is emitted, this results from the conversion of _____ ______.
Kinetic energy
The wavelength of an x-ray becomes _____ as projectile electron kinetic energy is reduced.
Longer
When projectile electron energy is increased ____ Brems x-rays are produced.
More
The efficiency of Brems x-ray production increases with increasing…
Target atomic number
The output intensity of an x-ray tube is primarily due to ______ x-rays.
Brems
What type of projectile electron target interactions result in x-ray emission?
Removal or inner shell electrons
When a projectile electron enters a target atom and interacts with the nuclear force field, it _____ in velocity.
Decreases
What will determine the amount of heat produced on the filament?
mA
What is the space surrounding the filament?
Space charge
What are electrons that are being slowed down as they pass the nucleus called?
Brems
What does the speed of the electrons coming from the filament to the anode depend on?
kVp (the energy or force)
If an exposure is made at 90 kVp, you’ll have Brems photons in the primary beam ranging from 0-90 kVp. What will the majority of them be?
30 kVp
What is a positive ion (photoelectron?)
An atom that has lost (1) negative charge
If a projectile electron hits the k-shell and an electron from the L-shell fills it’s spot, what will be the energy of the photon that is produced?
57 keV
If a k-shell electron is kicked out, then a photon is produced of 57 up to ____ keV.
69
What is the atom that is left behind with one less electron?
Positive ion
How many different x-ray energies could you get from Tungsten?
-15
K-5 L-4 M-3 N-2 O-1 P-0
How can you increase the probability of a characteristic interaction happening when you make an exposure?
- Incident electron must have a keV greater than, but close to the binding energy of the k-shell (69 plus a little)
- Having a target with a high atomic number
When shooting a CXR at 110 kVp, how much of that radiation will be characteristic radiation?
- None, until it slows down through Brems interactions
- They aren’t produced until they loose energy down to 69 plus a little
The primary beam is _________.
Polyenergetic
What is the formula for x-ray efficiency production?
% eff= (k) (z) (kVp)
k= .0001 (constant)
z= atomic number
What happens to efficiency percentage when you increase kVp?
It goes higher
When you increase kVp, what happens to the efficiency of x-ray production?
It goes up
How efficient is the x-ray machine at producing x-rays?
Inefficient
Where does the heat production occur?
Electrons from the cathode colliding with the outer shell electrons of the target atoms
Under certain circumstances electromagnetic radiation behaves as a ______ and at other times it behaves as a ________.
- Wave (of energy)
- Particle
What is the dual nature of a wave and a particle known as?
The Wave- particle duality of radiation
To best understand x-rays it is necessary to consider them as both waves and ______ of energy.
Particles
What is the wave theory?
X-rays exist as vibrating electric charges or waves
What is the Quantum/ Photon/ Particle theory?
X-rays exist as particles of energy
What is a photon?
Bundle of energy
Photon energy is _____ proportional to frequency.
Directly
The quality of the x-ray beam refers to the ability of an x-ray beam to ______ matter.
Penetrate
The quality of an x-ray beam can be specified by what (2) methods?
- HVL
2. Applied voltage
What is the Half Value Layer?
Thickness of a specified material which reduces the exposure rate to 1/2 its initial value
What is the voltage that is applied to the tube called?
kVp
What is the term used to designate beam quality, since HVL does not serve a useful purpose?
kVp
Filters harden the beam via the process of the…
Photoelectric effect
