Chapters 15, 16, 17: Nuclear Medicine

Class notes, no quiz

Radioactivity

nuclear transformations resulting in formation of new elements

Radioactivity modes depend on ___

energy available for transition

Alpha decay

emits a helium nucleus, occurs when neutron to proton ratio is too low

Beta minus decay

emits a charge particle that is indistinguishable from an ordinary electron, ocurrs when neutron to proton ratio is too high

Beta Plus / Positron decay

a beta particle with a positive charge, emitted when neutron-proton ratio is too low and alpha emission is not energetically possible

Electron capture delay

extranuclear electrons captured by nucleus form a neutron, occurs when there is a neutron deficiency but not enough energy for a positron.

Activity equation

A = A_oE^(γt) : rate of decay of a radionucleotide

The rate of decay represents the activity of a quantity of radioactive material in which ___

3.7 x `0^10 atoms are transformed in one second

___ decay is constant

gamma decay

Half Life equation

T1/2 = ln(s)/γ = 0.693/γ : time required for any radionucleide to decrease to 0.5 of original quantity

Decay constant

fractional decrease in activity per unit time (γ); varies by material

Good radiopharmecuticals have the following qualities: ___ radiation dose, ___ radiation detection efficiency, ___ specificity, ___, ___ effective

low; high; high; safety (non-toxic); cost

The three types of radionuclide production

cyclotrons, nuclear reactors, radionuclide generators

Cyclotrons

charged particle accelerator utilizing two large magnets producing a constant magnetic field; accelerated charged particles are collided, which decay with emissions of proton/neutron/electrons

Cyclotrons are used to produce most ___ radionuclides

PET

Nuclear reactors

produce radionuclides with nuclear fission or nuclear activation, splitting heavy atoms into smaller nuclei

Nuclear reactors are used to produce most ___ radionucleides

???

Radionuclide generator

a short-lived medical radionuclide produced by the decay of a longer lived radionuclide

“Molycows” refer to the radionucleide produced by ___

“milking” the Tc-99m from the Mo-99 resin during the radionuclide generator process

Radionuclide generators produce most of the ___ radionuclide

Technitium-99m

Effective half life equation

T_eff = (1/T_physical + 1/T_biological0)^-1 = (T_physical x T_biological) / (T_physical + T_biological)

Gamma cameras use ___ detectors to convert radiation to ___

scintillation cameras; lights

The most common crystal used in Gamma cameras is ___

Nal(Tl): sodium iodine crystals doped with thallium

The Gamma Camera’s PMT is responsible for…

converting the scintillator’s light into electrical signals using