When projectile electrons interact with the target anode in an x-ray tube, how are x-rays produced?
- Bremsstrahlung
- Characteristic
What does Bremse mean?
Brake
What does Strahlung mean?
Radiation
What is a Bremsstrahlung interaction?
When a high speed electron passes close to the nucleus of the target atom, and is pulled in by its electric field, which causes it to “brake” and get deflected from its course with a loss of energy in the form of an x-ray
Why does the nucleus electric field cause the electron to brake?
Because the nucleus is positive and the electron is negative, and positive/negative charges attract
What is the probability the incoming electron interacts with the inner sphere of the nucleus?
2%
What is the probability the incoming electron interacts with the outer sphere of the nucleus?
20%
If an electron passes through the inner sphere of the target nucleus, what type of x-ray will be produce?
High-energy x-ray photon
If an electron passes through the outer sphere of the target nucleus, what type of x-ray will be produce?
Low-energy x-ray photon
What happens as a result of the electron slowing/breaking?
It loses energy in the form of an x-ray photon and changes its own direction
What is the resulting x-ray photon called in a Bremsstrahlung interaction?
Bremsstrahlung x-ray
What happens if all the energy of the projectile electron is not given up during a Bremsstrahlung interaction?
It can go through several more interactions deeper into the anode, each producing new x-ray photons at lower energy levels
What does the varying levels of photon energies contribute to the x-ray beam?
Its heterogenous quality - beam of varying energies
What is a characteristic interaction?
When a high speed electron interacts with an inner shell electron of a target atom and ejects a K shell electron, leaving a vacancy
What happens to the atom, when the K shell electron is removed?
The atom because ionized and is no longer neutral
What is the minimum energy level needed for a characteristic interaction?
59-69 keV
What happens as a result of the vacancy in the K shell in a characteristic interaction?
An electron from an adjacent cell (L shell) will move into its space and lose energy which is released as an x-ray
What is the name of the x-ray produced as a result of filling the shell vacancy?
Characteristic x-ray
When will the shell vacancy filling end?
When all spaces are filled and the atom is stable again
What is the energy of the characteristic x-ray equal to?
The difference between the K and L shell energy levels
Which shell produces the only photon sufficient enough for diagnostic radiography?
K shell
At what kVp levels are characteristic x-rays produced?
At kVp levels greater than 70 but only in small numbers
Which of the two target interactions makes up most of the x-ray beam?
Bremsstrahlung interaction
What does it mean when a x-ray beam is heterogenous?
It contains many different energies (Because of Bremsstrahlung and Characteristic interactions)
