Characteristic x-rays Flashcards
Characteristic x-rays result when the interaction is violent to ionize the target atom through total removal of an _____________ _________.
inner-shell electron
What happens if an incident electron from the cathode possesses at least 69 keV?
it can collide with and remove a K-shell electron from a tungsten atom
What percentage of characteristic x-rays make up the primary beam when 70+ kVp are selected?
about 10%
What is the cascading effect?
when the cathode electron ionizes a target atom by removing a K-shell electron, and the L-shell moves into the vacancy
What happens when there is a void in the K-shell?
the L outer-shell falls into the void
The transition of an orbital electron from an outer shell to an inner shell is accompanied by the emission of an _______.
x-ray
What happens when an outer shell electron drops into an inner shell to fill a void left by ionization?
a characteristic photon is produced
L-shell electrons have a binding energy of ________
12 keV
How much keV is the leftover electron in a Tungsten atom?
69 keV - 12 keV = 57 keV
The energy of x-rays created by the K-shell electron interaction is _____________.
predictable
(they’re always 57 keV)
What does it mean when we say characteristic x-rays make up the “discrete” spectrum of x-rays?
they make up a very small portion of the total spectrum of the beam
At 100 kVp, the percentage of characteristic x-rays will increase to approx. ______ of the primary beam.
15%
Characteristic x-rays are ______________ than bremsstrahlung x-rays and vice versa
no better
In the spectrum graph, characteristic x-rays are the _______ and everything else is bremsstrahlung
spike
the number of protons determines the ________ __________ of the atom
atomic number
What are atoms comprised of?
a nucleus surrounded by shells that contain electrons
What does the nucleus contain?
the atom’s protons and neutrons
At 65 kVp how many characteristic x-ray photons will be produced?
none
What is the minimum energy for a cathode electron to ionize a tungsten atom?
69 keV
What happens if there is no ionization?
there is no cascading effect, which results in no characteristic x-ray
What percentage of the primary beam will be made of characteristic photons with a kVp setting of 65?
0%
During the process of characteristic x-ray production, the cascade effect refers to the:
electron transfer from the outer shell to the inner shell
Electron binding energy is defined as the:
energy required to remove an electron from orbit
What is the approx. energy of photons at position C (characteristic photons) of the spectrum?
69 keV
The most useful characteristic x-ray photons are produced when incident electrons interact with what?
inner shell electrons
How much energy is required to remove a K-shell electron from a tungsten atom?
69 keV
What name is given to the innermost electron shell within an atom?
K-shell
A characteristic photon’s energy depends on what two variables?
energy of the incident electron
binding energy of orbital electrons
