xray interaction with matter

diagnostic xray interactions

classical, compton, photoelectric

radiation therapy xray interactions

pair production and photodisintegration

classical scattering

xray photon does not lose energy

does ionization occur in classical scattering

no

other terms for classical scattering

coherent, rayleigh, unmodified, thompson

classical scattering kV value

below 10kV

compton/modified scattering

scattered photon has less energy due to recoil/compton electron and only collides with outer shell electrons

does ionization occur in compton scattering

yes

as the angle of the scatter increases, the photon energy:

decreases

backscatter

photon is directed back toward xray tube

photoelectric interaction

incident xray photon is absorbed and inner shell electron is ejected

does an photoelectric interaction have ionization

yes

how is characteristic radiation produced

inner shell is ejected and outer electron fills the orbit

does the incident photon have to be lesser or greater than k shell electron energy in a photoelectric interaction

greater

characteristic radiation

produces secondary radiation that is dependent on atomic number

as atomic number increases, the binding energies of shells:

increases

as atomic number increases, the photoelectric interaction:

increases

pair production occurence

1.02 MeV or higher

pair production process

• high energy photon comes close to nucleus and loses its energy

• 2 electrons are emitted into a negatron and positron

• negatron is quickly absorbed and positron combines with a free electron

• positron and electron combine and produce 2 more photons (.51 MeV each)

• matter is converted back to energy

photodisintegration

incident xray hits the nucleus and ejects a nuclear fragment

photodisintegration occurence

10 Mev or higher