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25 Cards in this Set
- Front
- Back
stability curve- which line is line of stability
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curved line
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Alpha Decay often are ___ because nuclear origin and is called ___ __
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photons, gamma rays
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alpha decay __Neutrons __ Protons
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2N 2P
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like an e- but emmited because of nuclear decay
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beta-minus decay (B-)
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ejected from nucleus with positive charge
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beta-plus decay (B+)
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proton decays into neutron and proton
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pair production
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e- from outer shells fall foward in nucleus to fill hole
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characteristic radiaiton
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1 dis/sec=
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1 Bq
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when half-like pf parent is much greater then half-life of daughter isotope
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secular equilibrium
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reduce to 1/2 original, defined by both energy and attenuating material
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half value layer
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HVL=
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0.693/m
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HVL is also a description of
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beam quality "hard" or "soft"
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"soft"
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-less penetrating
-deposit energy quickly but [*high LET] |
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low energy
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xray have inherent filtration in machine
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high energy (linac/betatrons) in treatment
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head- harden beam
helps uniform dose across patient |
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Type photon interactions (5)
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1. Thompson (coherent) scattering
2. Photoelectric scattering 3.Comptom (incoherent) scatteringk 4. Pair production 5. Photodisenegration |
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Rad Therapy units use ___ energies
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1-5 Compton!!
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e- and e- interactions
ejected completely |
ionized
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e- and e- interactions
kicked up to shell far from nucleus |
excitation
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Bremstrahlung
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high energies pass close to the nucleus slow down lose kinetic energy
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Thompson scattering
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-photon interaction
-same energy photon as incident photon -except in different direction -outer shell -wavelength and energy equal "coherency" -low energy photon -not enough to ionize -in a new direction |
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Compton (incoherent) Scattering
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-photon interaction
-most common interaction in Radiation Therapy -photon interacts with outer shell e- -outer shell - in new direction with less energy, also causes dose -produces scattered e- or "recoiled e-" |
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Photoelectric scattering
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-photon interaction
-most common in xray -photon interactions with either K, L [inner shell] -ejects photoelectron -vacancy filled by outer e-, produces characteristic radiaiton -Auger e- -more likely in high z materials -low energy photons xrays |
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Pair production
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-photon interactions
-with nucleus -makes B- and B+ -only with photon energy of 1.022 mev or higher -B+ joins free e- and "anialation reaction" -B- joins any other free atom -anialation occurs 180 degrees from each other with .511 energy -not significant until 10 mev -absorbed by nucleus |
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Photodisinigration
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-photon interaction
-photon absorbed in nucleus -emits neutron -emits gamma rays |