2. Ragnar Hellborg Lund University PRODUCTION OF CLINICALLY USEFUL QUANTITIES OF 18 F BY AN ELECTROSTATIC TANDEM ACCELERATOR Ragnar Hellborg Lund University, Sweden PET = positron emission tomography

3. Ragnar Hellborg Lund University Different radio-nuclides that decay by positron emission IsotopeHalf-lifeMax positron energy (MeV) 11 C20.1 min0.96 13 N9.96 min1.19 15 O123 s1.72 18 F110 min0.64 64 Cu12.6 h0.58 68 Ga68.3 min1.9 76 Br16.1 h3.7 82 Rb78 s3.35 124 I4.18 days1.5

4. Ragnar Hellborg Lund University Nuclear reactions for production of 18 F: *) 18 Ne decays to 18 F with a half-life of 1.67 s ReactionTargetThreshold (MeV) Energy of max cross section (MeV) 19 F(γ,n) 18 FTeflon10.4 23 Na(γ,αn ) 18 FNaOH or NaSO 4 21 18 O(p,n) 18 FH 2 18 O or O 2 2.45 20 Ne(d,α) 18 F0.1%F 2 in Ne-6 16 O( 3 He,n) 18 Ne*H2OH2O-8 16 O(α,d) 18 FH2OH2O18 16 O(t,n) 18 FLi 2 CO 3 -3.3 23 Na(p,αx) 18 FNa18.7

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8. Ragnar Hellborg Lund University Target chamber design

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12. Ragnar Hellborg Lund University There are two goals in designing scanners: * To detect as many photon pairs as possible to achieve a high signal-to-noise level. The quality depends on the amount of radioactivity, the image time and the sensitivity of the scanner. * To localise photon interactions in the scanners as accurately as possible. This determines the spatial resolution. Two limiting factors: 1) the distance the positron travels before it annihilates. For 11 C and 18 F a few tenths of a mm. 2) The electron and positron are not completely at rest when they annihilate. This means an angle slightly below 180º giving a small positioning error. For human PET scanners this error can be a few mm.

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16. Ragnar Hellborg Lund University Our applications are: Diagnosing tumours with other techniques like X-ray computed tomography (CT), ultra sound, magnetic resonance etc., it can sometimes be difficult to separate malign changes from more harmless. Examples of the later can be scars, modifications of the tissue after surgery etc. PET gives information about the metabolic status, it is therefore possible to separate a malign tumour in which the metabolism is higher from other changes. Planning for treatment it is extremely important to have information about the localisation and shape of the tumour as this will strongly influence on the quality of the treatment. For example a small and local tumour can be treated by surgery, a non local tumour with daughter tumours will not primarily be treated by surgery. After treatment it can be difficult to separate between modifications depending on the treatment or another possible tumour. Also in this case PET can be of good help. In the same way if a new tumour appears in a newly treated area it is difficult to separate from other changes of the tissue without using PET. During treatment (by radiation or chemotherapy) it is very valuable to follow by PET the changes of the tumour as a result of the treatment.

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18. Ragnar Hellborg Lund University

19. Forms of cancer clinically investigated in Lund: Lung cancer Very often the PET investigation discovers daughter tumours resulting in a modified treatment planning. Large intestine. At recurrence it is important to get information about the distribution of the new tumour(s) before taking decision about surgery or other types of treatment. Head and neck cancer. When daughter tumours have been recognised in this area it can be difficult to find the primary tumour - often small and hidden - without using PET. Ragnar Hellborg Lund University

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