PET tracers Flashcards
What does PET imaging rely on?
Nature of the positron & positron decay
What is a positron?
Antimatter counterpart to the electron (same mass, opposite charge)
What happens as positrons pass through matter?
Lose energy through ionization & excitation of nearby atoms & molecules
Positrons will then annihilate with an electron
and emit 2 511keV gamma rays
What are the 4 most common labels for PET tracers?
O15
N13
C11
F18
What is the clinical use for oxygen-15?
oxygen metabolism
cerebral blood flow
What is the clinical use for carbon-11?
dopamine uptake studies
amino acid metabolism
What is the clinical use for fluorine-18?
Glucose metabolism
Dopamine storage
What is the clinical use for nitrogen-13?
Blood flow
myocardial perfusion
What are the 5 basic operating principle of a cyclotron?
Source of ions
Accelerate particles to high energies
bombard target
nuclear reaction within target
radioisotope produced
How many dee electrodes does a typical cyclotron consist of?
2 dee electrodes - -ve ions produced from ion source at centre of dees
Why is an alternating voltage applied?
So the ions move back and forth between the dees
What does the strong magnetic field perpendicular to the plane do?
Constraints the path of ions to a circular orbit which increases in diameter as ions pick up energy from the electric field
What does the thin carbon stripping foil do?
Strips 2 electrons from each H- leaving an H+ ions which curves away from the dees under the influence of the magnetic field
What is the proton beam directed onto and why?
Onto a target where protons undergo a nuclear reaction with the target material
What is FDG?
Form of glucose which is normally absorbed by the body but not metabolized or excreted therefore it accumulates where glucose is intensely utilized
