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@PHDTHESIS{Hild:184427,
      author       = {Hild, Sebastian},
      othercontributors = {Bert, Christoph and Fietkau, Rainer and Hensel, Bernhard
                          and Durante, Marco},
      title        = {{A}daptive {T}reatment of prostate carcinoma in scanned ion
                      beam therapy [cumulative {P}h{D}]},
      school       = {Friedrich-Alexander-Universität Erlangen-Nürnberg},
      type         = {Dr.},
      reportid     = {GSI-2016-00157},
      pages        = {-},
      year         = {2015},
      note         = {The Thesis is presented as a cumulative work of two
                      publications (see linked works).
                      https://repository.gsi.de/record/96010 and
                      https://repository.gsi.de/record/184394 .;
                      Friedrich-Alexander-Universität Erlangen-Nürnberg, Diss.,
                      2015},
      abstract     = {Radiation therapy for prostate carcinoma (PCa) is
                      challenged in part by large target dislocations between
                      single fractions (interfraction motion). To prevent
                      geometrical target misses, in clinical practice the volume
                      to be irradiated is enlarged by so called safety margins of
                      typically 5 to 12 mm, in some cases even up to 15 mm, in any
                      direction. The extension causes an unnecessary dose
                      delivered to healthy tissue and radiation sensitive organs
                      like the bladder and the rectum. Toxicity in these organs
                      restricts the maximum target dose which has been found to
                      improve tumor control if increased. In this work, adaptive
                      radiation therapy (ART) strategies have been analyzed for
                      their possible application in prostate cancer therapy. For
                      this purpose, scanned ion beam therapy, which is known to
                      feature a highly conformal dose delivery, was combined with
                      two ART strategies: image guided target definition and daily
                      plan re-optimization. As a proof of concept, the treatment
                      planning software for particles TRiP, developed at GSI
                      Helmholtz Center for Heavy Ion Research (GSI) in Darmstadt,
                      Germany, has been optimized for calculation speed. A
                      reduction of computation time from 4 hours to 6 min for a
                      two-field prostate plan demonstrated the plausibility of
                      daily plan re-optimization. In addition a treatment
                      simulation study on a dataset containing 60 computed
                      tomography scans (CTs) of ten prostate cancer patients has
                      been designed comparing the performance of image guided
                      target definition and daily plan re-optimization with
                      conventional one plan radiotherapy. In the presented dataset
                      $20\%$ of the patients showed considerable motion (mean 3D
                      vector length > 4 mm). The fraction of the target volume
                      receiving at least $95\%$ of the prescribed target dose in
                      $5\%$ of all fractions $(V955\%)$ for these patients was
                      lower than 0.64 (mean 0.87) and lower than 0.66 (mean 0.91)
                      for conventional one-plan particle therapy and image guided
                      target definition, respectively. In patients showing only
                      small motion(mean 3D vector length < 4 mm), image guided
                      target definition reduced the mean rectal volume receiving
                      more than $60\%$ target dose (V60mean) by $13\%$ at slightly
                      but significantly improved target coverage. Daily
                      re-optimization, the most versatile correction method, kept
                      target coverage in all patients above $95\%$ of the
                      prescribed dose and reduced the rectal V60mean by $37\%$ and
                      $47\%$ for patients with large and small motion,
                      respectively, due to the possible margin reduction. It has
                      been shown in this work that treatment replanning can become
                      possible in the future. Patients exhibiting large prostate
                      motion will greatly benefit of such on line adaptation
                      strategies, while adaptation could be completely omitted in
                      patients showing small prostate displacements only. For
                      motion classification, pre treatment motion assessment,
                      using repeated imaging sessions, would be the preferable
                      approach. The best suited treatment modality/protocol that
                      way can be determined before a therapy course is started and
                      reduce the additional workload coming from adaptation
                      protocols to a minimum. Treatment replanning still waits for
                      advances in hard- and software development, to ease the
                      entire TRP process and thereby permit integration in a
                      clinical environment. Based on the findings of this work,
                      dedicated motion management is indicated for one fifth of
                      the patients in PT of the prostate.},
      cin          = {BIO},
      ddc          = {610},
      cid          = {I:(DE-Ds200)BIO-20160831OR354},
      pnm          = {315 - Imaging and radiooncology (POF3-315)},
      pid          = {G:(DE-HGF)POF3-315},
      typ          = {PUB:(DE-HGF)11},
      url          = {https://repository.gsi.de/record/184427},
}