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PET Cyclotron

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PET Cyclotron PET Cyclotron Presentation Transcript

  • Radionuclide production methods
    • Cyclotron
    • Nuclear reactor
    • Radionuclide generator
  • CYCLOTRON Pawitra Masa-at 4937092 SIRS/M January 31, 2007
  • Basics of PET Tracer Production
  • Generates high-energy particles Generate PET radionuclide Generates TRACER
  • Particle Accelerators
    • CYCLOTRON
      • One of the earliest types of particle accelerators
      • Cyclotron are source of a large number of high-energy (MeV) range charged particle .
    • CTI RDS-Eclipse
    • shelf-shielding cyclotron
    • Accelerations proton to 11 MeV .
    • MINI trace (GE)
    • shelf-shielding cyclotron
    • Accelerate protons to 9.6 MeV
    Cyclone 18/9
    • PET trace (GE)
    • 16.5 MeV negative ion cyclotron
    • Six target proton and deuteron
  • Physics of cyclotron
    • A device invented by E .  O .  Lawrence and M .  S .  Livingston at Berkeley in 1931
    • that is used to accelerate charged particles by means of a magnetic field .
    • A particle of mass (m ) and charge (q ) moving with a velocity ( v ) will interact with a magnetic field of strength ( B ) whose direction is perpendicular to the plane of its travel with force
    • The force of the magnetic field
    • The force of the electric field
    • Charged Particle in an EM Field
    • Lorentz force
  •  
    • Centripetal force on particle in an orbit
    • The force of the magnetic field is perpendicular to the particle's direction, resulting in a circular path inside the cyclotron. Equating F with a centripetal force gives
    • Homogeneous magnetic field in which case,
    • So
    • Where then T (time) can be written as
    • RF oscillator frequency
    For particle of constant mass , the frequency does not depend upon the radius of the particle’s orbit.
  • As the beam spirals out, its frequency does not decrease, and must continue to accelerate, as it travelling more distance in the same time.
    • As mentioned earlier, this is a constant frequency orbital accelerator,
    • but one in which the orbit radius increases. Frequency given by
    …………… .
  • Max KE achievable: ………… ..
  • Cyclotron Component
    • Major Exterior Component
      • Shielding
    • Major Interior Component
      • Vacuum system
      • Ion Source
      • Magnetic system
      • Radiofrequency system
      • Dees
      • Beam extraction
      • Targets
  • Vacuum System
    • High vacuum (10 -6 , 10-8) needed to reduce interaction of accelerated particles with air molecules.
    • prevents the creation of other unwanted nuclides.
    • Electrical insulation of the DEEs.
    • All material needs to be compatible with level of vacuum .
  • Ion Source
    • Provide the source of ions (proton or deuteron) that that will be accelerated
    • Introduce the ion into magnetic field
    • The input to the ion source is 99.9995% pure hydrogen.
    • mounted in the centre of the cyclotron.
    p+ e- e-
  • Ion source system (cont) Ion Source
  • Magnetic System
    • Provide the magnetic field
    • Makes the ion travel in circular orbit
    • Keeps the beam of ions focused and compact.
  • Charged Particle in an EM Field
  • Radiofrequency System (RF)
    • Pulls the ions out of the ion source.
    • The RF oscillates about the two Des at high frequency and voltage.
    • Push and Pull particles around the cyclotron
    • Accelerates the ions to the specified energy prior to its bombardment.
  • RF System (cont) Flaps Fine tuning RF frequency Stem Supplying RF power to Dee’s
  • Dees
    • Electrode inside the cyclotron.
    • Pulse with fluctuating negative and positive charges.
    • to “push” and “pull” the ions through the circular acceleration.
  • DEEs Ion Source
  • Particle acceleration
  • Beam Extraction
    • Thin carbon foil placed at the extraction radius
    • Electron are tripped off Ion become Positron.
      • Remove the “-” e - in the case of F-18 production
    • No beam losses here.
  •  
  • Beam Extraction (cont) H - Ion source Creates the ion Orbits controlled by magnet field RF System Accelerates the ion Carbon foil H + Extraction System Changes polarity of ions 16.5 MeV p+ e- e- p+ e- e- p+ e- e-
  • Target
    • Targets are located outside the cyclotron
    • The high energy particle beam of protons hit the nucleus (of the target material) & cause a nuclear reaction.
    • The target material can be a gas, liquid or solid.
  • Radionuclide Production
    • Reactions with different particles  need to accelerate different particles
    • Different reaction thresholds  need to accelerate to different energies
  • Uses of Cyclotrons
    • Multi-particle, multi-energy cyclotrons:
      • very flexible, but
      • complex machines
      • often positive ion cyclotrons
    • Dedicated cyclotron:
      • usually 2 types of particles (p and d) and
      • 1 fixed energy for each particle
      • typical for negative ion cyclotrons
  • Advantage of Cyclotron
    • Produce atom has different charge.
    • High specific activity / short half-life.
    • Biochemical atoms.
  • Cyclotron Radioisotope
    • For PET studying
    • Nuclide T 1/2 Production
    • Carbon-11 20.4 min 10 B(d,n) 11 C
    • Nitrogen-13 9.96 min 12 C(d,n) 13 N
    • Oxygen-15 2.05 min 14 N(d,n) 15 O
            • 16 O(p,pn) 15 O
    • Fluorine-18 110 min 18 O(p,n) 18 F
  • Cyclotron Radioisotope
    • other
    • Nuclide T 1/2
    • Cobalt-57 272 d  marker for in-vitro kits.
    • Gallium-67 78 h  tumour imaging & localization of infection
    • Indium-131 2.8 d  diagnostic studies ; brain, infection, colon transit studies
    • Iodine-123 13 h  diagnostic of thyroid function
    • Rubidium-82 65 h  myocardial perfusion imaging
    • Strontium-92 25 d  parent of Rb-82 in generator
    • Thallium-201 73 h  dianostic of heart condition etc.
  • Thank You 