Production cross sections of light positron emitters 11C (t1/2=20.36 min), 13N (t1/2=9.97 min) and 15O (t1/2=122 s) have been measured for proton-induced reactions on the main relevant constituents of the human body (C, N and O) from threshold up to 200 MeV of proton incident energy. This has been accomplished by means of two complementary experiments at the clinical proton treatment centers WPE (Essen) and HIT (Heidelberg), both in Germany. In the first case, the multi-foil activation technique was combined with PET imaging, a methodology previously developed at CNA (Seville, Spain). In the second experiment, aimed at energies below 50 MeV, the activation of single foils was measured with conventional LaBr3 detectors. In both cases the IAEA monitor reaction natCu(p,x)63Zn data was used for validation purposes. The most complete and accurate set of excitation functions for the production of light-positron emitters 11C, 13N and 15O in proton induced reactions on human tissue up to 200 MeV is presented. These data are needed for nuclear reaction model development and are extremely important to improve the accuracy of the PET range verification in proton radiotherapy. Seven excitation functions have been measured: 12C(p,x)11C, 14N(p,x)11C, 14N(p,x)13N, 14N(p,γ)15O, 16O(p,x)11C, 16O(p,x)13N and 16O(p,x)15O up to 200 MeV of proton incident energy.

The research work presented herein has received funding from the Spanish Ministry of Economy and Competitiveness projects under grants no RYC-2014-15271, FPA2016-77689-C2-1-R and RTI2018-098117-B-C21, from the EC project H2020-847552 (SANDA), from the “Consejería de Economía y Conocimiento de la Junta de Andalucía” project under grant no. P18-RT-1900, from the Regional Ministry of Economy, Knowledge, Business and University/FEDER funds under grant no. US-1380791 and from the “V Plan Propio de Investigación (V PPIT-US)” programme from the University of Sevilla. M.C. Jiménez Ramos acknowledges the support to this work through a VI PPIT-US contract. J. Bauer acknowledges funding from the Universtity of Heidelberg as Olympia-Morata fellow. T. Rodriguez-Gonzalez acknowledges the Spanish FPI PhD grant associated to the project FPA2016-77689-C2-1-R.

Peer reviewed