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@ARTICLE{Longarino:177254,
      author       = {F. Longarino$^*$ and T. Tessonnier and S. Mein$^*$ and S.
                      B. Harrabi and J. Debus$^*$ and W. Stiller and A. Mairani},
      title        = {{D}ual-layer spectral {CT} for proton, helium, and carbon
                      ion beam therapy planning of brain tumors.},
      journal      = {Journal of applied clinical medical physics},
      volume       = {23},
      number       = {1},
      issn         = {1526-9914},
      address      = {Reston, Va.},
      publisher    = {ACMP},
      reportid     = {DKFZ-2021-02388},
      pages        = {e13465},
      year         = {2022},
      note         = {#EA:E050# / Volume23, Issue1 January 2022 e13465},
      abstract     = {Pretreatment computed tomography (CT) imaging is an
                      essential component of the particle therapy treatment
                      planning chain. Treatment planning and optimization with
                      charged particles require accurate and precise estimations
                      of ion beam range in tissues, characterized by the stopping
                      power ratio (SPR). Reduction of range uncertainties arising
                      from conventional CT-number-to-SPR conversion based on
                      single-energy CT (SECT) imaging is of importance for
                      improving clinical practice. Here, the application of a
                      novel imaging and computational methodology using dual-layer
                      spectral CT (DLCT) was performed toward refining
                      patient-specific SPR estimates. A workflow for DLCT-based
                      treatment planning was devised to evaluate SPR prediction
                      for proton, helium, and carbon ion beam therapy planning in
                      the brain. DLCT- and SECT-based SPR predictions were
                      compared in homogeneous and heterogeneous anatomical
                      regions. This study included eight patients scanned for
                      diagnostic purposes with a DLCT scanner. For each patient,
                      four different treatment plans were created, simulating
                      tumors in different parts of the brain. For homogeneous
                      anatomical regions, mean SPR differences of about $1\%$
                      between the DLCT- and SECT-based approaches were found. In
                      plans of heterogeneous anatomies, relative (absolute) proton
                      range shifts of $0.6\%$ (0.4 mm) in the mean and up to
                      $4.4\%$ (2.1 mm) at the distal fall-off were observed. In
                      the investigated cohort, $12\%$ of the evaluated
                      organs-at-risk (OARs) presented differences in mean or
                      maximum dose of more than 0.5 Gy (RBE) and up to 6.8 Gy
                      (RBE) over the entire treatment. Range shifts and dose
                      differences in OARs between DLCT and SECT in helium and
                      carbon ion treatment plans were similar to protons. In the
                      majority of investigated cases (75th percentile), SECT- and
                      DLCT-based range estimations were within 0.6 mm.
                      Nonetheless, the magnitude of patient-specific range
                      deviations between SECT and DLCT was clinically relevant in
                      heterogeneous anatomical sites, suggesting further study in
                      larger, more diverse cohorts. Results indicate that patients
                      with brain tumors may benefit from DLCT-based treatment
                      planning.},
      keywords     = {brain tumors (Other) / dual-layer spectral CT (Other) / ion
                      beam therapy planning (Other) / range uncertainties (Other)
                      / stopping power (Other)},
      cin          = {E050 / E210 / HD01},
      ddc          = {530},
      cid          = {I:(DE-He78)E050-20160331 / I:(DE-He78)E210-20160331 /
                      I:(DE-He78)HD01-20160331},
      pnm          = {315 - Bildgebung und Radioonkologie (POF4-315)},
      pid          = {G:(DE-HGF)POF4-315},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:34724327},
      doi          = {10.1002/acm2.13465},
      url          = {https://inrepo02.dkfz.de/record/177254},
}