Experimental study on the feasibility of in-beam PET for accurate monitoring of proton therapy

Katia Parodi, Falk Pönisch, Wolfgang Enghardt

Research output: Contribution to journalArticle

89 Scopus citations


Positron emission tomography (PET) is currently the only feasible method for in-situ and noninvasive three-dimensional monitoring of the precision of the treatment in highly conformal ion therapy. Its positive clinical impact has been proven for fractionated carbon ion therapy of head and neck (H&N) tumors at the experimental facility at the Gesellschaft für Schwerionenforschung (GSI), Darmstadt, Germany. Following previous promising experiments, the possible extension of the method to the monitoring of proton therapy has been investigated further in extensive in-beam measurements at GSI. Millimeter accuracy for verification of the lateral field position and for the most challenging issue of range monitoring has been demonstrated in monoenergetic and spread-out Bragg-peak (SOBP) proton irradiation of polymethyl methacrylate (PMMA) targets. The irradiation of an inhomogeneous phantom with tissue equivalent inserts in combination with further dynamic analysis has supported the extension of such millimeter precision to real clinical cases, at least in regions of interest for low perfused tissues. All the experimental investigations have been reproduced by the developed modeling rather well. This indicates the possible extraction of valuable clinical information as particle range in-vivo. irradiation field position, and even local deviations from the dose prescription on the basis of the comparison between measured and predicted activity distributions. Hence, the clinical feasibility of in-beam PET for proton therapy monitoring is strongly supported.

Original languageEnglish (US)
Pages (from-to)778-786
Number of pages9
JournalIEEE Transactions on Nuclear Science
Issue number3 II
StatePublished - Jun 1 2005


  • PET
  • Proton therapy
  • Therapy monitoring

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • Electrical and Electronic Engineering

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