Speaker
Description
In proton therapy, PET range verification requires a comparison of the measured and expected $\beta^{+}$ activity distributions produced by the beam in the body of the patient by means of nuclear reactions. The accuracy of the expected activity distributions depends on that of the Monte Carlo simulations, and hence by that of the underlying cross sections data [1]. These are not available in the full energy range of interest (up to 230 MeV) and, when they are, there are sizable discrepancies between data sets. Indeed, several studies confirm the need for more and better measurements and evaluations [2,3].
In this work we have measured the production yields of the long-lived positron emitters $^{11}$C, $^{13}$N and $^{15}$O in the most abundant elements in the human body (carbon, nitrogen and oxygen) in the full energy range for proton therapy (up to ~230 MeV). The method employed consists in the combination of the multi-foil activation technique followed by the measurement of the induced activity with a clinical PET scanner. The foils used are rich in C, N and O, with polyethylene layers between them to reduce the beam energy from one foil to the next. The method has been successfully used and tested below 18 MeV at CNA (Sevilla, Spain) to obtain the differential cross sections for these reactions (paper to be submitted soon).
The experiment was carried out at the West German Proton Therapy Centre (WPE) in Essen (Germany), with three initial beam energies: 190, 150 and 100 MeV. The experimental set up and preliminary results will be presented.
[1] Tárkányi et al. J. Radioanalytical and Nuclear Chemistry. 319 533–666 (2019)
[2] España et al., Phys. Med. Biol. 56(9) 2687-2698 (2011)
[3] E. Seravalli et al., Phys. Med. Biol. 57 1659 (2012)
