Ragnar Hellborg

Lund University

PRODUCTION OF CLINICALLY USEFUL QUANTITIES OF 18F BY AN ELECTROSTATIC

TANDEM ACCELERATOR 

Ragnar HellborgLund University, Sweden

PET = positron emission tomography

Ragnar Hellborg

Lund University

Different radio-nuclides that decay by positron emission

Isotope Half-life Max positron energy (MeV)

11C 20.1 min 0.9613N 9.96 min 1.1915O 123 s 1.7218F 110 min 0.6464Cu 12.6 h 0.5868Ga 68.3 min 1.976Br 16.1 h 3.782Rb 78 s 3.35124I 4.18 days 1.5

Ragnar Hellborg

Lund University

Nuclear reactions for production of 18F:

*) 18Ne decays to 18F with a half-life of 1.67 s

Reaction Target Threshold (MeV)

Energy of max cross section (MeV)

19F(γ,n)18F Teflon 10.423Na(γ,αn )18F NaOH or

NaSO4

21

18O(p,n)18F H218O or O2 2.4 5

20Ne(d,α)18F 0.1%F2 in Ne - 6

16O(3He,n)18Ne*

H2O - 8

16O(α,d)18F H2O 18

16O(t,n)18F Li2CO3 - 3.3

23Na(p,αx)18F Na 18.7

Ragnar Hellborg

Lund University

Ragnar Hellborg

Lund University

Ragnar Hellborg

Lund University

Ragnar Hellborg

Lund University

Target chamber design

Ragnar Hellborg

Lund University

Ragnar Hellborg

Lund University

Ragnar Hellborg

Lund University

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 11C and 18F 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.

Ragnar Hellborg

Lund University

Ragnar Hellborg

Lund University

Ragnar Hellborg

Lund University

  

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.

 

Ragnar Hellborg

Lund University

Ragnar Hellborg

Lund University

PET/CT

 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

Ragnar Hellborg

Lund University

Ragnar Hellborg

Lund University

Ragnar Hellborg

Lund University