MI 132 unit 4 Flashcards
(51 cards)
target interactions
incident electrons interact w/ target atoms (tungsten) to produce x-rays in the following 2 ways: characteristic and Brems
what is the most common interaction ?
Heat
incident electrons
aka: filament electrons and projectile electrons
-electrons are boiled off from the cathode and interact at the anode
less than _% of electrons interact w/the ability of making x-ray
1%
excitation
related to the production of heat
-takes an ion/electron and makes it at a higher state
-not enough to kick out of orbit
what is a heat a result of
excitation, not ionization
Bremsstrahlung
interacts with the force field of the nucleus
-slows down incident electrons
-electron loses energy because It slowed down
-1 incident electron can have multiple interactions with its target
what is Brem’s course
Doesnt divert course because it is losing energy
how does distance effect Brem’s
distance from nucleus determines how much energy your electron is going to lose and how much the photon energy will be
what is the line difference in Brem’s and incident photons
=xray photons are a squiggly line
-incident photons are straight lines
Brem math
find the difference between energy it comes in with and what it leaves with
how does distance effect incident electrons
distance effects the amount of kinetic energy lost by incident electrons
-the CLOSER to the nucleus, the MORE energy LOST
-the FURTHER from the nucleus, the LESS energy LOST
where does Brems energy fall?
1/3 of kVp
how is max and min Brem’s determined
max: determined by kVp (if kVp is 80, Brems wont exceed 80)
min: immeasurable because it is so low
characteristic xray photons
ionization pf a target electron needed first and then electron will be kicked out of orbit
-higher energy electron will drop into lower energy shell and an xray photon is created
ionization in characteristics
ionization of k-shell (most inner shell) is important when thinking about characteristic interactions
characteristic math
difference in shell energy/ electron binding
what is the kVp for K-shell?
69.5
-for tungsten
highest photon energy will be farthest shell to closest shell
what changes characteristic xray photons ?
change in target material because it has a different binding energy
what happens to low kEv?
it is absorbed into the patient
k shell electrons
the only useful electrons that contribute to the image of your xray and its useful to characteristic interactions
what does kVp change?
kVp does not change effect energy of the shell in Characteristics but it DOES in Brems
characteristic cascade
when ionizing a shell, the shell that fills an open space will be empty until another shell fills the space
characteristic photon produce when…
produce when an outer shell electron fills inner shell vacancy
