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99mTc and UK Opportunities Hywel Owen and David Brett School of Physics and Astronomy University of Manchester.

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Presentation on theme: "99mTc and UK Opportunities Hywel Owen and David Brett School of Physics and Astronomy University of Manchester."— Presentation transcript:

1 99mTc and UK Opportunities Hywel Owen and David Brett School of Physics and Astronomy University of Manchester

2 Cardiac Imaging

3 Mo-99/Tc-99m/Tc-99 Tc-99m isomerism Seaborg and Segrè, Phys. Rev. 54(9), 772 Seaborg and Segrè, Phys. Rev. 55(9), 808 143 keV Tl-201 (made with a cyclotron, t1/2~3d) emits at 80 keV (through electron capture) which is not as good for imaging

4 Some facts about 99mTc Hospital imaging: 1.Computed Tomography 2.Nuclear Medicine (85% Tc-99m) 3.MRI 35 M procedures/yr (global) Primarily cardiac imaging – e.g. post heart-attack Nuclear Medicine USA29 M (44%) Europe9 M (22%) Tc-99 Usage All Tc-99m28 M Cardiac12 M World weekly supply: 2g of 235U used, 0.11g Mo-99 provided $140 M

5 Emilio Segrè and the 37-inch cyclotron deflector foil ‘In February 1937 I received a letter from Lawrence containing more radioactive stuff. In particular, it contained a molybdenum foil that had been part of the cyclotron's deflector. I suspected at once that it might contain element 43. The simple reason was that deuteron bombardment of molybdenum should give isotopes of element 43 through well-established nuclear reactions. My sample, the molybdenum deflector lip, had certainly been intensely bombarded with deuterons, and I noted that one of its faces was much more radioactive than the other. I then dissolved only the material of the active face, in this way achieving a first important concentration of the activity. ‘

6 235U fission

7 99Kr Decay Chain NuclideHalflife 99Y1.470(7) s 99Zr2.1(1) s 99Nb15.0(2) s 99Mo2.7489(6) d 99Tc2.111(12)E+5 a 99RuStable

8 Research and Power Reactors Research reactors – Better neutronics, but need high power (>20 MW) – Easier fuel cycle: can extract targets out quickly and process them, needed to obtain Mo-99 – Only 5 reactors meet these requirements

9 Major producers of Mo-99 Broken Recently broken No UK production of 99Mo, although we use ~1 million doses a year

10 Technetium Generators Typical price UKP 400-600, gives ~100 doses (depending on modality), 100-250 GBq (3-7 Ci) 92,000 sold in USA in 2005 Total market around 600 MEuro, but this is artificially cheap because of cross-subsidy from nuclear research Only few companies worldwide doing either processing or packaging: General Electric (50%), MDS Nordion, Covidien (25%), Mallinckrodt, NTP ‘Demand is 200% of supply’ (Alan Perkins, BNMS) Typical Mo-99 specific activity 3000 Ci/gm (0.6%)

11 Problems with the reactor method Reactors are all very old, with disrupted replacement plans: – MAPLE-1/2 cancelled – 1997-2007: 4 disruptions – 2007-2009: 5 disruptions – May 2009 & October 2009 are shortage months when 3 reactors are down. Uranium enrichment – 5% for power, e.g. PWR – 20% for research – 95% for Mo-99 (or bombs) – LEU < 20% – HEU >20% 95% of global HEU use is for Mo-99 production – USA does not like HEU being shipped around in boxes

12 Switching to LEU targets Use LEU (around 20% 235U) – Needs about 5 times as much Uranium as a (95%) HEU target, since the 238U doesn’t do anything. No-one is using LEU and associated processing – yet – Mo-99 purity will be about the same Target is not bigger, since you use different U density – Use U foil target (8g/cm3) rather than UO2 (1.6 g/cm3) or extruded U/Al rods – Use Cintichem process for extraction Still 50 Ci of waste per 1 Ci of Mo (c.f. 30:1 with 235U) LEU target issues – 25 times more 239Pu generated (due to 238U n capture) – but alpha contamination is about the same (due to 234U concentration during enrichment) (Vandegrift et al., Industrial & Engineering Chemistry Research 39(9), 3140 (2000)) Mushtaq et al., NIM B 267, 1109 (2009)

13 Mo-99 Candidate Production Methods AcceleratedIncidentReactionCommentsReference Deuteron 98Mo(d,p)99MoSegre and Lawrence ProtonNeutron100Mo(n,2n)99MoNagai & Hatsuwaka, JPSJ 78, 033201 (2009) Proton 100Mo(p,2p)99,99mNb(β-)99Mo N/ANeutron98Mo(n,γ)99MoReactor MoW.Diamond, AECL Oct 2008 Ryabchikov et al., NIM B 213, 364 (2004) ProtonNeutron98Mo(n,γ)99MoBe/Pb targetFroment al., NIM A 493, 165 (2002) N/ANeutron235U(n,f)99MoReactor method ProtonNeutron235U(n,f)99Mo~1 GeV Proton 238U(p,f)99MoLagunas-Solar, Trans.Amer.Nucl.Soc. 74, 134 (1996) ElectronGamma100Mo(γ,n)99Mo30 MeVDikiy et al., Nuclear Physics Investigations (42), p.191-193 (2004) ElectronGamma235/238U(γ,f)99MoPhotofission/RIBCoceva et al., NIM 211, 459 (1983)

14 Tungsten Target, Gamma Production, then Photofission Berger and Seltzer, Phys Rev C 2, 621 (1970) 235U 238U Diamond, NIM A 432, 471 (1999) (also benefits from neutron reflection and fission cascade) Haxby et al., Phys. Rev. 58(1), 92 (1940)

15 Photofission Yields De Clerq et al., Phys Rev C 13 (4), 1536 (1976) P. Bricault, TRIUMF Diamond, NIM A 432, 471 (1999) ‘A radioactive ion beam facility using photofission’

16 Related target geometry (RIB) P. Bricault, TRIUMF

17 Bremsstrahlung spectrum Bremsstrahlung yield from GEANT4 different geometry (W at the top, Al at the bottom)

18 ALICE Cavities high current cavity under construction; to be evaluated in 2010

19 Liquid (Solution)/Solid Target for Photonuclear Mo (Kharkov) Dikiy et al., Nuclear Physics Investigations (42), p.191-193 (2004) Dikiy et al., EPAC’98 Either solid or aqueous solution target (Na 2 MoO 4 /K 2 MoO 4 ) Yield in solution is very low, but yield in target is ok (e.g. ~1 Ci from 24h at 1mA Target should be enriched 100Mo to avoid production of other isotopes (expensive) 100Mo(γ,n)99Mo

20 Photonuclear Cross-Section in 100Mo W.Diamond, AECL, Oct 2008 Around 100 Ci/g with 100kW/50MeV electrons into W About 2 atoms in 10,000 (cf ~10% in fission products) - this requires a different (bigger?) generator - normal generator 60 in 10000 Target design is crucial ‘Photofission is likely not practical’ Sabelnikov et al., Radiochemistry 48(2), 191 (2006) - report 390 mb with direct irradiation with 25 MeV electrons

21 ORNL ORELA Neutron target design (Diamond/Beene)

22 Photofission yields using GEANT4 Wrong peak at A=110; trying to work out why De Clerq et al., Phys Rev C 13 (4), 1536 (1976)

23 Adiabatic Resonance Crossing (Rubbia) Rubbia, CERN/LHC/97-04 Arnould et al., Phys. Lett. B 458, 167 (1999)

24 Epithermal neutron capture in 98Mo Ryabchikov et al., NIM B 213, 364 (2004)

25 Resonant Neutron Capture Van Do et al., NIM B 267, 462 (2009) IsotopeAbundance Abs (barn) Pb---0.171 204Pb1.40.65 206Pb24.10.03 207Pb22.10.699 208Pb52.40.00048 Lethargy Froment al., NIM A 493, 165 (2002)

26 Carlo Rubbia patent Patent 2005/0082469 (2005) Resonant neutron capture in Mo, possibly Na2MoO4 solution

27 Two possible pilot accelerator systems 50 MeV, 10-100 mA, e- – Bremsstrahlung convertor – 238U photofission in depleted U – (100Mo photonuclear) This fits well with CI SC cavity developments – Can do tests at 20 MeV, 10 mA Greenfield site: – Probably photofission is best, but targets need comparison and optimisation 50-800 MeV, ~1 mA, p+ – Spallation convertor – 235U fission in LEU – 98Mo epithermal n capture This fits well with AESIR proposal – Whatever the accelerator, we can use it. – Do tests at ISIS? ‘Free’ proton accelerator: – Resonant neutron capture is an unoptimised problem, and is promising

28 TRIUMF Plans TRIUMF have long-standing involvement with MDS-Nordion on medical isotope production using ~30 MeV proton cyclotrons Recent report is a response to Canadian isotope crisis – Propose high power e- linac and photofision

29 UK Plans and Elsewhere Cockcroft would like to develop a demonstrator Mo-99 facility Full commercial facility with hot cells probably on nuclear site, e.g. Sellafield Target design needs to be done as part of demo design – i.e. done early Work out which way is best, and estimate yields for each method TRIUMF have collaboration with MDS- Nordion – Non-disclosure agreement! Manchester have submitted an STFC funding application to look at target design Presently figuring out applicability of GEANT, FLUKA and MCNP to each design problem – Got unreliable results from GEANT4, and trying to work out why – Got FLUKA2008 and MCNP4c running test cases – Plenty of work to go round!

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