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@ARTICLE{Telsemeyer:128418,
      author       = {J. Telsemeyer$^*$ and B. Ackermann and S. Ecker and O.
                      Jäkel$^*$ and M. Martisikova$^*$},
      title        = {{E}xperimental verification of ion range calculation in a
                      treatment planning system using a flat-panel detector.},
      journal      = {Physics in medicine and biology},
      volume       = {59},
      number       = {14},
      issn         = {1361-6560},
      address      = {Bristol},
      publisher    = {IOP Publ.},
      reportid     = {DKFZ-2017-04434},
      pages        = {3737 - 3747},
      year         = {2014},
      abstract     = {Heavy ion-beam therapy is a highly precise radiation
                      therapy exploiting the characteristic interaction of ions
                      with matter. The steep dose gradient of the Bragg curve
                      allows the irradiation of targets with high-dose and a
                      narrow dose penumbra around the target, in contrast to
                      photon irradiation. This, however, makes heavy ion-beam
                      therapy very sensitive to minor changes in the range
                      calculation of the treatment planning system, as it has a
                      direct influence on the outcome of the treatment. Our
                      previous study has shown that ion radiography with an
                      amorphous silicon flat-panel detector allows the measurement
                      of the water equivalent thickness (WET) of an imaging object
                      with good accuracy and high spatial resolution. In this
                      study, the developed imaging technique is used to measure
                      the WET distribution of a patient-like phantom, and these
                      results are compared to the WET calculation of the treatment
                      planning system. To do so, a measured two-dimensional map of
                      the WET of an anthropomorphic phantom was compared to WET
                      distributions based on x-ray computed tomography images as
                      used in the treatment planning system. It was found that the
                      WET maps agree well in the overall shape and two-dimensional
                      distribution of WET values. Quantitatively, the ratio of the
                      two-dimensional WET maps shows a mean of 1.004 with a
                      standard deviation of 0.022. Differences were found to be
                      concentrated at high WET gradients. This could be explained
                      by the Bragg-peak degradation, which is measured in detail
                      by ion radiography with the flat-panel detector, but is not
                      taken into account in the treatment planning system.
                      Excluding pixels exhibiting significant Bragg-peak
                      degradation, the mean value of the ratio was found to be
                      1.000 with a standard deviation of 0.012. Employment of the
                      amorphous silicon flat-panel detector for WET measurements
                      allows us to detect uncertainties of the WET determination
                      in the treatment planning process. This makes the
                      investigated technique a very helpful tool to study the WET
                      determination of critical and complex phantom cases.},
      keywords     = {Silicon (NLM Chemicals)},
      cin          = {E040},
      ddc          = {570},
      cid          = {I:(DE-He78)E040-20160331},
      pnm          = {315 - Imaging and radiooncology (POF3-315)},
      pid          = {G:(DE-HGF)POF3-315},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:24936855},
      doi          = {10.1088/0031-9155/59/14/3737},
      url          = {https://inrepo02.dkfz.de/record/128418},
}