Production of xrays Flashcards
What are the four ways x rays interact at the atomic level?
Photoelectric effectCompton effectRayleigh scatteringPair production
What is the photoelectric effect?
process of pure x ray absorption
What happens between the electron and the x ray photon in the photoelectric effect?
incoming x ray photon interacts with a bound inner shell electron of tissue atomthe inner shell electron is then ejected with large amounts of energy into tissues and undergoes further interactions
What is the name of the electron that becomes knocked off in the photoeectric effect?
photoelectron
What happens to the x ray photon once it has given its energy to the electron in the photoelectric effect?
the photon disappears
What happens to the remainder of the electrons in the tissues during the photoelectric effect once the photoelectron becomes ejected? WHat happens in this process?
the electrons then drop down from outer shells to inner shells. this process produces energy in the form of light or heat
How is atomic stability then achieved once the electrons drop down from the outer shell to the inner shell in the photoelectric effect?
free electrons are captured
What is the effect of the high energy photoelectron on the rest of the tissues?
it is then free to interact with other tissues and maybe the cause of ionising radiation within the tissues which could lead to tissue damage
What is the probability of the photoelectric effect occurring within the tissues?
it is proportional to the atomic number of the protein ^3
Which tissue out of bone, dentine, enamel and pulp has the greatest atomic number?
bone hence why bone appears white because more x ray photons are absorbed (photoelectric effect)
What is the relationship between KV and photoelectric effect?
the lower the Kv the more likely the photoelectric effect will take place photoelectric effect proportional to 1/Kv^3
How is contrast produced on an x ray?
Photoelectric effect
T/F the photoelectric effect contributes to the total dose recieved by the pt?
Tbecause it is a process of pure absorption
What type of radiographic tool uses the photoelectric effect?
intensifyng screens
What is the compton effect?
this is the process of x ray absorption and scattering
WHen does the compton effect occur?
When there is higher energy photons
How does the compton effect work?
x ray photon interacts with a free/lossely bound outer shell electron of the tissue atomthe outer shell elctron is then ejected by using some energy from then incoming photon
What happens to the photon energy in the compton effect?
some is absorbedthe reminader is scattered
What happens to the direction of the x ray photon in the compton effect when an outer shell electron is encountered?
the photon changes direction and loses energy
WHat is the name of the electron in the compton effect that gets knocked off and what direction does it travel in?
recoilforward
In which tissues does the Compton effect occur more commonly in?
Any tissues since it is not dependant upon the atomic number rather it is dependant on the energy of the photon
WHat happens to the scattered photon in the Compton effect?
can undergo further Compton reactions with more tissuesundergo the photoelectric effect with tissuesescape the tissues and form scattered radation
T/F the Compton effect contributes greatly to the diagnostic information on the xray?
falseit does not provide information about the tissues s
What is the overall effect of both the photoelectric and Compton effect?
ionisation of the tissues