Münster 2002 – scientific programme
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HK: Physik der Hadronen und Kerne
HK 48: Instrumentation and Applications VI
HK 48.7: Talk
Thursday, March 14, 2002, 17:45–18:00, F
The potential of in-beam PET for proton therapy monitoring: first experimental investigation — •Katia Parodi1, Wolfgang Enghardt1, and Thomas Haberer2 — 1Forschungszentrum Rossendorf e.V., Postfach 510119, 01314 Dresden — 2Gesellschaft für Schwerionenforschung, Planckstr. 1, 64291 Darmstadt
On the basis of the positive clinical impact of in-beam PET on the quality assurance of carbon ion therapy at GSI Darmstadt [1] we started to investigate the potential extension of the technique to proton therapy. This is non-trivial, since protons cannot suffer the projectile fragmentation process which leads to a pronounced maximum of the β+ activity in close vicinity to the dose maximum in the carbon ion case.
In our experiment three monoenergetic proton beams in the energy and intensity range of therapeutic interest were stopped in targets of PMMA (C5H8O2) placed in the centre of the field of view of the in-beam positron camera installed at the GSI heavy ion therapy facility. The β+ activity signal was found to be three times larger than that induced by carbon ions at the same range and applied physical dose. The reconstructed spatial β+ activity distributions were well reproduced in shape by a calculation based on experimental cross-sections and on the proton flux given by the FLUKA Monte Carlo code. Despite the weaker spatial correlation between activity and dose depth-distributions in the proton case, our experiment supports the feasibility of in-beam PET for the monitoring of proton therapy based on a comparison between measured and calculated β+ activity distributions, as already implemented for carbon ion therapy.
[1] W. Enghardt et al, Nucl. Phys. A 654 1047c (1999)