Imaging Technologies II Flashcards
Definition of a particles
2 protons, 2 neutrons (He nucleus)
Definition of B- particles
An electron
Definition of B+/positrons
antiparticle of electron
Definition of isomeric transition
Nuclear process where a nucleus with excess energy following the emission of an a/b particle emits energy without changing the mass/atomic no
Definition of half life
The time then for half the nuclei to decay
Definition of nuclear magnetic resonance
When nuclei absorb energy from a radiofrequency waves applied at a specific frequency in a magnetic field
Definition of resonance frequency
Natural frequency of a system, frequency needed for most efficient energy transfer
Types of radioactive emissions
a particles b particles (b-) positrons y radiation xrays
Alpha decay
Natural radioactive elements heavier than Pb
Unstable radionuclide ejects a (helium nucleus)
Beta minus decay
Electron created in transformation = b-
v= antineutrino created in transformation
Atomic no increases by 1
Neutron no decreases by 1
Mass no, unchanged
Beta plus decay
Positron created in transformation = b+
v= neutrino created in transformation
Atomic no decreases by 1
Neutron no increases by 1
Mass no, unchanged
Positron annihilation and detection
Tracer decays and emits positron
Annihilation occurs with e-, releases 2 y photons at 180
Detected with 511keV
Isomeric transition
Nucleus with excess energy emits y after loss of a/b-/b+
99m 43 Tc emits y without changing atomic mass/no
Decay kinetics
Rate of decay = dN/dt = -lambda N
Lambda= decay constant
N= no of nuclei
1st order process
Half life
Time taken for half the nuclei to decay
T1/2 = In2/lambda