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Ch. 6 X-ray Production
Terms in this set (61)
What are the 2 interactions that can happen when the electrons hit the anode?
bremsstrahlung or characteristic radiation or interactions
Bremsstrahlung process produces more than what % of diagnostic x-rays?
The kinetic energy of the electrons is converted into what 2 things?
heat and X-ray energy
The interaction that will occur depends on what?
the electron kinetic energy and the electron binding energy of the target electron shells
The electrons that travel from the cathode to the anode are called what?
When the projectile electrons hit he anode what do they do?
they transfer their kinetic energy to the anode and interact with the atoms
The projectile electrons can interact with what two areas of an atom?
the nucleus or the orbital shells
An interaction with the outer shell electrons will produce what?
The production of heat is directly proportional to what?
-more current = more heat production
Regardless of what mA setting is used the X-ray production remains what?
The efficiency of X-ray production increases with the increasing what?
projectile electron energy (kVp)
-more projectile electron energy = more X-ray efficiency
voltage applied to the X-ray tube and is equal to the maximum energy of the projectile electrons
energy of the individual X-rays
describes the penetrating ability of the X-ray beam
-controlled by kVp setting
-energy of the photons produced
describes the X-ray beams intensity
-controlled by mA setting
-amount of photons produced
when the projectile electron interacts with an inner shell electron rather than the outer shell electron
When an inner shell electron is removed what happens?
an outer shell electron falls down to replace the lost electron called a characteristic cascade and is accompanied with the emission of an X-ray photon
The k shell has a binding energy of what in a tungsten atom?
The L shell has a binding energy of what in a tungsten atom?
The M shell has a binding energy of what in a tungsten atom?
The N shell has a binding energy of what in a tungsten atom?
Only X-rays from what shell are useful with diagnosis?
k shell characteristic X-rays, not X-rays from any other shell
Characteristic xrays are produced by transitions of orbital electrons from what shells to what shells?
outer shells to inner shells
Bremsstrahlung is German for what?
What type of reaction happens when a projectile electrons interacts with the nucleus force field of a target atom?
What is the process of a brems interaction?
the projectile electrons are attracted to the positive nucleus of the target atoms, as the projectile electron nears the nucleus it slows down and they lose their kinetic energy creating an X-ray photon and they then change direction
Low energy brems X-rays result from what type of interaction with the nucleus?
a slight interaction
What will create a maximum strength brems X-ray?
when the projectile electron looses all of its kenetic energy
Brems interactions may only occur when what happens?
when the incident electron interacts with the force field of the nucleus
Why do brems interactions create X-rays of many different energies?
because the incident electrons are slowed down at different rates
The closer the incident electron to the nucleus the ____ energy the X-ray will have with a brems interaction
The energy of a brems photon is the difference between what?
difference between the kinetic energy of the incident electron and the kinetic energy of the brems photon
a plot of the number of bremsstrahlung X-rays as a function go their different X-ray energies
-a plot of the number X-rays from 0 to the peak electron energy
The maximum energy (Emax) of the brems photons is equal to what?
the energy of the projectile electrons
Why does the X-ray spectrum never start at 0?
because the low energy X-rays are filtered out
The majority of X-rays produced have an average of approximately how much of the Emax?
one third of the Emax
What are the 2 energies associated with X-ray production?
keV and kVp
What is kVp equal to?
the maximum energy of the X-rays
What is characteristic X-ray energy the difference between?
the difference in energy between the binding energy of the vacant shell and the outer shell
-k shell binding energy - L shell binding energy = energy of characteristic X-ray energy
How many photons are produced from one electron leaving an atom in a characteristic interaction?
How does a characteristic interaction happen?
an incident electron with the energy of 70 keV knocks a k shell electron out of its shell, so it is filled with an outer shell electron and as it moves down a shell to fill the vacancy it gives off radiation called a characteristic cascade
The characteristic interactions created at the anode target are called what?
The most common transition between shell electrons is between what two shells?
K and L shells
All characteristic X-rays resulting from L to K transitions in a tungsten anode have an energy of what?
M to K transitions produce what energy?
K characteristic X-rays are only produced at what range of kVp?
In diagnostic X-rays taken in the range of 110 to 120 about what percentage of the beam is K characteristic X-rays?
Does the energy of the K characteristic photon change with changes in kVp?
What area of the X-ray spectrum is represented by the intensity or quantity?
the area under the curve
The average energy of the beam is represented by what area of the X-ray spectrum?
the position of the peak of the curve
What 4 things effect the X-ray spectrum?
kVp, mAs, filtration, and circuit waveform
How does kVp effect the spectrum?
it affects both quality and quantity by changing the amplitude and also the position of the peak
A higher kVp does what to the spectrum?
increases the amplitude of the peak and also shifts it to the right
How does mAs affect the spectrum?
it affects only quantity
If mAs is increased what does it do to the spectrum?
increases the amplitude but not the position of the peak
Does the number of characteristic xrays increase with increased mAs?
yes but the characteristic energy does not change
The quantity of the X-ray beam is directly proportional to what?
to the mAs
What is the purpose of filtration?
to filter out the low energy photons to reduce patient dose
How does filtration affect the spectrum?
it will decrease quantity and increase average energy of the beam so the spectrum will decrease in amplitude and shift the peak to the right
How will a more efficient X-ray circuit affect the spectrum?
it will increase the the quality and quantity of the beam
What is the discrete portion on the spectrum?
where the characteristic reactions happen (at 70 keV)
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