PET Cyclotrons

PET Cyclotrons Bill Alvord CTI Cyclotron Systems The PET process CCS PETNET 18O water Cyclotron Chemistry [18F]FDG Distribution CPS, CDM, ACT, Mirada Service Physician/ Patient Scanners Information services PET Isotope Logistics • Decay – Each radioisotope has a unique half-life. – The four commonly used isotopes in PET and their half lives are: Isotope F-18 C-11 N-13 Half life 109.8 minutes 20.2 minutes 9.96 minutes O-15 122 seconds PET Isotope Logistics • Decay - review • There is a fixed probability of decay for each nucleus resulting in exponential decay. • The time it takes for the decay rate to drop to half its value is called the half-life • The decay rate at a given period of time can be calculated by •where: • A0 = decay rate at t = 0 • t1/2 = half life (in same units as t) • t = time since A0 was measured (same units as t1/2) A(t )  A0  e0.693t t1/ 2 PET Isotope Logistics Decay of 1 Ci of F-18 over 8 hours 1125 1000 875 750 625 500 375 250 125 0 0 60 120 180 240 minutes 300 360 420 480 Activity (mCi) PET Isotope Logistics • Activation – Stable nuclei can be bombarded with nucleons (neutrons or protons) or other nuclei to form activated nuclei – This process is referred to as a nuclear reaction – The nomenclature for nuclear reactions is target nucleus(bombarding particle, recoiling particle)product nucleus – For example 18O(p,n)18F means 18O bombarded by protons results in 18F and a neutron PET Isotope Logistics • Production – As a nuclear reaction takes place, the population of activated nuclei grows, as does the decay rate – At some point the decay rate and activation rate are equal – The activity at this point is saturated. The saturation activity is an indication of the production rate. Knowing the saturation activity one can calculate the expected activity at any time using the following equation: A(t )  Asat 1  e  0.693t t1/ 2  PET Isotope Logistics • Production curve – Saturation activity is an indication of production rate – Production rate is proportional to current Accumulation of activity during two production cycles 3500 3000 300 250 200 150 100 50 0 0 60 120 180 240 300 360 420 Time (minutes) Activity (mCi) 2500 2000 1500 1000 500 0 PRoduction rate (mCi/minute) Activity Production rate PET Isotope Logistics • Yield curve – Saturation activity is an indication of production rate – Production rate is proportional to current – Production rate is dependent on energy F-18 Thick target saturation yield vs. energy 300 Yield (mCi/uA at sat.) 250 200 150 100 50 0 0 2 4 6 8 Energy (MeV) 10 12 14 16 Corporate structure CTI, Inc. CTI PET Systems, Inc. • ECAT R&D & Production • ECAT Product Support • Siemens, CTI, & Hitachi are distr. of CPS products CTI Cyclotron Systems • RDS R&D • RDS Production CTI Services • Radioactive Sources • RDS and US ECAT Service • Marketing & Sales PETNet, Inc. • PETNet PMDCs & Nuclear Pharmacies • LA Tech Center ACT, Inc. & CDM • BGO Crystal Production • LSO Detector Material R&D • LSO Detector Material Production CTI – The Power Behind PET The cyclotron as seen by... …the operator …the inventor …CFO …the customer The first cyclotron Vacuum Deflector E.O. Lawrence - 1932 Dee Filament Cyclotron components Dee stem Dee Ion source Hill Valley Cyclic particle acceleration Magnetic field (Lorentz) force • No good for accelerating by itself • Can curve charged particle orbits    F  qv  B B E B E E B E B Target port Beam extractor Ion source Curved orbit on hills (high magnetic field) Hills Straight orbit in valleys (low magnetic field) Fully Upgradeable Product Family eclipse HP eclipse RD eclipse ST •Research system •Up to 16 Targets •High Production system •Up to 8 Targets •Entry level system •Up to 8 Targets UPGRADE PATH CCS Production Standard Products Shielded Cyclotrons 16 Target Locations Upgrade paths Largest Installed Base Eclipse RD Retractable Shields Cyclotron - 22,000 pounds 1 Power Supply Cabinet 1 Control Cabinet 1 Water System Cabinet Shields - 60,000 pounds Cabinets - 3,200 pounds Total = 85,200 pounds Space Constraints • • • • 22 ft w x 23ft d x 10 ft h room for cyclotron and all utilities 1.5 mR/Hr shielding available No bunker, no separate control room Flexible remote operation capabilities CTI System Comparable Systems Four Dee Accelerator Design • Four Dees Provide More Periods of Acceleration per Orbit – particles spend less time in accelerator – reduced internal activation • Top-mounted Components – easier service – improved alignment Single Port / Multi-Position Targets • Integrated Target Support • Shared utilities minimize leaks and reduce complexity • Target Umbilicals • Targets can be installed or removed with one screw • Target change requires no intervention in vacuum • Design minimizes personnel exposure time CTI Cyclotron product features • Lowest Power-In / Highest Product Out • Lowest Radiation Fields in the Industry • Greatest Flexibility: 16 Targets with 64 combinations • Highest Gas Specific Activity (5X to 10X higher) • Only Available Remote Control Capabilities • Largest Installed Base and Service Organization Cyclotron Room • PETNet Dallas Chemistry Lab • PETNet Dallas Phase plot PET Isotope Targets - Design Target elements PET Isotope Targets - Design • Design constraints – Temperature – Pressure – Medium and phase (liquid water or hot gas) – Chemistry – Volume – Lifetime – Energy/yield PET Isotope Targets - Design • Support equipment – Small volumes, high pressures and low contamination – Much of the equipment comes from HPLC • • • • • • Capillary tubing Chromatography valves (up to 1000 psig) Pressure transducers Syringe pumps Diaphragm pumps HPLC pumps PET Isotope Targets - Systems Isotope: 18F Reaction: 18O(p,n)18F Chemical form: Fluoride ion (F-) Target material: 18O enriched water (argon overpressure) Target volume: 1.1 ml Target body: 99.99% pure silver Target window: .001” thick Havar (high strength Nickel-Cobalt alloy) Typical pressure: 650 psig beam off, 800 psig beam on PET Isotope Targets - Systems Isotope: 18F Reaction: 18O(p,n)18F Chemical form: Fluorine gas (F2) Target material: 18O enriched gas (Ar/5% F2 second shoot) Target volume: 7 ml (120 std. cc gas) Target body: Aluminum Target window: .001” thick Havar (high strength Nickel-Cobalt alloy) Typical pressure: 280 psig beam off, 900 psig beam on PET Isotope Targets - Systems Isotope: 13N Reaction: 16O(p,α)13N Chemical form: Ammonium ion (NH4) in water Target material: 5 mMol Ethanol in HPLC water Target volume: 2 ml Target body: Aluminum Target window: .001” thick Titanium Typical pressure: 320 psig PET Isotope Targets - Systems Isotope: 15O Reaction: 15N(p,n)15O Chemical form: Oxygen gas (O2) in Nitrogen gas (N2) Target material: 15N enriched Nitrogen gas with 2.5% O2 Target volume: 7 ml (120 std. cc) Target body: Aluminum Target window: .001” thick Havar (high strength Nickel-Cobalt alloy) Typical pressure: 280 psig beam off, 900 psig beam on PET Isotope Targets - Systems Isotope: 11C Reaction: 14N(p,α)11C Chemical form: Carbon dioxide gas (CO2) in Nitrogen gas (N2) Target material: unenriched Nitrogen gas with 2.5% O2 Target volume: 7 ml (120 std. cc) Target body: Aluminum Target window: .001” thick Havar (high strength Nickel-Cobalt alloy) Typical pressure: 280 psig beam off, 900 psig beam on Computational fluid dynamics and water targets • Problem: Dissipate 1000 W in an 800 μl volume; lose less than 5% of that volume to evaporation over 2 hours of irradiation • Irradiation chamber is pressurized to 650 psig with Argon (raises the boiling point of the water to 240 C). • CFD helps determine the appropriate shape and surface area of the enclosure Pet tracer logistics summary • Small is Beautiful. – Why make more neutrons than you need? • Distance is the enemy. – We are shipping ice cream cones. • More is better. – Replication is the key.