F. Ponisch

Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Saxony, Germany

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Publications (6)1.22 Total impact

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    ABSTRACT: Respiratory motion can introduce image artefacts not only in 3D PET but also in 4D PET due to incorrect attenuation correction. In this work the influence of different attenuation correction strategies on 3D and 4D PET has been investigated. An extensive phantom study was carried out, using a normal 3D CT (pitch 1.5), a slow 3D CT (pitch 0.5), an ultraslow 3D CT (pitch 0.15), an average CT and a maximum intensity projection calculated from a 4D CT (pitch 0.1) for attenuation correction of both a 3D and 4D PET of a respiratory motion phantom. Additionally, the 4D PET was corrected phase-wise with a 4D CT (phase-correlated attenuation correction). The reconstructed PET images were analyzed concerning the reconstructed volume, motion amplitude (for 4D PET), activity concentration and activity distribution. Moreover a patient study was carried out investigating the influence of the different attenuation correction strategies for 4D PET to patient data. Therefore 4D PET data from six patients with non-small cell lung cancer (NSCLC) was alternatively attenuation corrected with a normal 3D CT, an average CT and with phase-correlated attenuation correction. The tumor volume was analyzed and the motion amplitude of the tumor was obtained from the 4D PET data sets. For the phantom data the attenuation correction with the slow CT results in the best agreement between expected and measured values of the examined quantities in 3D PET, whereas in 4D PET this was the case for the phase-correlated attenuation correction. In the patient study only small differences between the 4D PET attenuation correction methods were found. This can be explained by the relative small tumor motion in the patient population investigated (peak to peak amplitude below 5 mm except for one patient).
    Nuclear Science Symposium Conference Record, 2008. NSS '08. IEEE; 11/2008
  • Source
    K. Parodi, F. Ponisch, W. Enghardt
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    ABSTRACT: 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 fur 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.
    IEEE Transactions on Nuclear Science 07/2005; · 1.22 Impact Factor
  • Source
    K. Parodi, F. Ponisch, W. Enghardt
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    ABSTRACT: Positron emission tomography is currently the only feasible method for in-situ and non-invasive 3D 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 tumours at the experimental facility at the Gesellschaft fur Schwerionenforschung Darmstadt (GSI), 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. Millimetre accuracy for verification of the lateral field position and for the most challenging issue of range monitoring has been demonstrated in mono-energetic and SOBP proton irradiation of PMMA targets. The irradiation of an inhomogeneous phantom with tissue equivalent inserts in combination with further dynamic analysis has supported the extension of such millimetre 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.
    Nuclear Science Symposium Conference Record, 2004 IEEE; 11/2004
  • F. Ponisch, W. Enghardt, K. Lauckner
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    ABSTRACT: The in-beam dual head positron camera BASTEI (Beta+ Activity meaSurements at the Therapy with Energetic Ions) is used to monitor and control the applied dose distributions simultaneously to tumor irradiations with carbon ion beams at the experimental heavy ion therapy facility at GSI Darmstadt. Therefore, the PET system has been mounted directly at the treatment site. A fully 3D reconstruction algorithm based on the Maximum Likelihood Expectation Maximization algorithm has been developed and adapted to a spatially varying imaging situation. The scatter and attenuation correction is applied to the measured list mode data before each iterative step. This requires an attenuation map containing the information on the tissue composition and densities. This information is derived from the X-ray computed tomograms (CT) of the patient and the patient fixation system including the head rest. The scatter correction is included into the forward projection step of the Maximum Likelihood image reconstruction. The normalization of scattered events relative to the unscattered events is done by a global scatter fraction factor. The results are presented
    Nuclear Science Symposium Conference Record, 2001 IEEE; 02/2001
  • Source
    F. Ponisch, W. Enghardt, FZ Rossendorf

Publication Stats

42 Citations
1.22 Total Impact Points

Institutions

  • 2001–2005
    • Helmholtz-Zentrum Dresden-Rossendorf
      • Institute of Radiation Physics
      Dresden, Saxony, Germany