nucs physics Flashcards
band of stability
balance of protons and neutrons
alpha decay
-release of He (2n + 2p)
-high linear E transfer (heavy, lim range (1 cm/meV)
-not used in img, used in therapy
radioactive decay
releasing excess neutrons or protons to reach balance
b-decay: too many neutrons or protons? What’s formed?
-too many neutrons
-b-particle, positively charged nuc, anti-neutrino (massless, balance out E)
b-particle
negative charge ejected from nucleus during b-decay to form balanced nuc
isobaric transition-what is it, what does it occur with?
-no change in mass (because you lost neutron and gained positive charge but they weigh the same)
-occ with b-minus, b-positive (positron emission & electron capture)
how do you block b-emission in a syringe?
plastic shield (low Z). if you used high Z (ex: lead) –> bremmmstahlung xray
What sort of b-decay occ with too many protons and not enough neutrons?
1) b-positive
2) electron capture
b-positive decay: what does it require?
1.02 MeV
what’s formed with b-positive decay?
positron + neutrino (worthless POS for balancing E)
what occ with b-positive decay?
positron emitted, collides with electron –> two 511 keV photons emitted 180˚ apart from each other
electron capture
a nucleus with too many protons steals an electron from inner (K) shell to become neutral
is b-minus decay good for img?
No, electron emission can damage DNA (basis of radionuclide therapy)
is e-capture good for img?
yes, bc it’s linked to isomeric transition which results in emission of char gamma photon which can be imaged under gamma camera
isomeric transition
emission of E (ex: in form of gamma photon) after isobaric transition as a final step to create nuc stability
-mult gamma photons released=mult peaks, ex: Ga67, In-111
