PET Radiopharmaceuticals

  1. What are theĀ 3 common PET agents used?
    • Nitrogen 13
    • F18
    • Rb 82
  2. What are the 2 types of cyclotrons?
    Postive Ion Cyclotron: proton accelerated

    • Negative Ion Cyclotron: proton+2 e
    • -tungsten filament heated>ionizes H+ gas intro protons that gain 2 electrons> negative ions get pulled into cyclotron by magnetic device.
  3. When was the first cyclotron made and by whom?
    Ernest Lawrence in 1930
  4. What are the 5 systems that make up the cyclotron? (VIRME)
    • Vacuum
    • Ion Source
    • Radiofrequency System
    • Magnetic System
    • Extraction System
  5. What does the vacuum system do?
    Removes air, atoms or molecules
  6. What does the Ion Source System do?
    Creates plasma from which the negative ions are extracted to form the ion beam for acceleration

    ARC power supply=plasma created by electrical current

    Bias power supply=H- pulled from the plasma thru a small slit and then thru the puller in to the main acceleration region
  7. What does the Radiofrequency System do?
    Accelerates the ion beam

    **Alternating current accelerates H- ions**
  8. What does the Magnetic System do?
    Controls the path of the ion beam w/n the cyclotron
  9. What does the Extraction System do?
    • Carbon extraction foil is catches beam of H-
    • THEN
    • Beam strikes foil and becomes positive
    • THEN
    • Beam is diverted towards the target
  10. What is the coincidence circuit used for in PET imaging?
    To identify true events
  11. What is spatial resolution affected by in PET imaging?
    • 1. Positron Range
    • 2. Residual kinetic energy and momentum (how far it travels)
  12. What are the 6 steps in making FDG?
    • 1. F18 Fluoride Production
    • 2. Trap and release of F18 fluoride ion
    • 3. Prep of F18 fluoride ion
    • 4. Radiolabeling
    • 5. Hydrolysis
    • 6. Purification
  13. Describe the process of F18 fluoride ion production
    Proton Bombardment of O18 water (target material) with F18

    Transfer to chemistry module
  14. Describe the process of trapping and releasing of F18 fluoride ion
    • 1. Load O18 and F18 to chemistry module
    • 2. Rinse with Potassium Carbonate
    • (O+F)+K= (K+F) + O

    • F18 will stick to resin and become purified (K+F18)
    • The water will washout and can be recycled
  15. What are the 3 requirements for F18 Fluoride ion
    • Must have no water (anhydrous)**Important b/c H2O forms bonds with fluoride so F18 won't be able to to bind**
    • Must be in solution (soluble)
    • Must be reactive
  16. How is Fluoride Ion made Anhydrous?
    1. Remove K by adding Kryptofix 222 (forms a cage around K so it doesn't react with fluoride)

    2.Add acetonitrile and azeotropic distillation to get rid of water

    3.Add more acetonitrile to resolublize the dried F18 complex
  17. Describe how to Radiolabel F18 FDG
    • C2 is at the nucleus of the triflate group
    • F- is a nucleophile (nucleus loving)
    • F18 displaces the C2 triflate group to form glucose

    **The acetyl groups protect the hydroxyl groups which force the F18 to remove C2**
  18. Describe the Hydrolysis Step in making FDG
    Use NaOH to remove acetate groups to yield FDG molecule
  19. How do you purify FDG?
    Neutralize using acid or base

    • Eliminates:
    • Unreacted F18 ion
    • Unhydrolyzed F18
    • K222
    • Acetonitrile
    • Microbial Contamination
Card Set
PET Radiopharmaceuticals