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@ARTICLE{ElShafie:157092,
      author       = {R. A. El Shafie and E. Tonndorf-Martini and D. Schmitt and
                      A. Celik and D. Weber and K. Lang and L. König and S. Höne
                      and T. Forster and B. von Nettelbladt and S. Adeberg and J.
                      Debus$^*$ and S. Rieken and D. Bernhardt},
      title        = {{S}ingle-{I}socenter {V}olumetric {M}odulated {A}rc
                      {T}herapy vs. {C}yber{K}nife {M}6 for the {S}tereotactic
                      {R}adiosurgery of {M}ultiple {B}rain {M}etastases.},
      journal      = {Frontiers in oncology},
      volume       = {10},
      issn         = {2234-943X},
      address      = {Lausanne},
      publisher    = {Frontiers Media},
      reportid     = {DKFZ-2020-01383},
      pages        = {568},
      year         = {2020},
      abstract     = {Introduction: Stereotactic radiosurgery (SRS) is becoming
                      more frequently used for patients with multiple brain
                      metastases (BMs). Single-isocenter volumetric modulated arc
                      therapy (SI-VMAT) is an emerging alternative to dedicated
                      systems such as CyberKnife (CK). We present a dosimetric
                      comparison between CyberKnife M6 and SI-VMAT, planned at
                      RayStation V8B, for the simultaneous SRS of five or more BM.
                      Patients and Methods: Twenty treatment plans of CK-based
                      single-session SRS to ≥5 brain metastases were replanned
                      using SI-VMAT for delivery at an Elekta VersaHD linear
                      accelerator. Prescription dose was 20 or 18 Gy, conformally
                      enclosing at least $98\%$ of the total planning target
                      volume (PTV), with PTV margin-width adapted to the
                      respective SRS technique. Comparatively analyzed quality
                      metrics included dose distribution to the healthy brain
                      (HB), including different isodose volumes, conformity, and
                      gradient indices. Estimated treatment time was also
                      compared. Results: Median HB isodose volumes for 3, 5, 8,
                      10, and 12 Gy were consistently smaller for CK-SRS compared
                      to SI-VMAT (p < 0.001). Dose falloff outside the target
                      volume, as expressed by the gradient indices $GI_high$ and
                      $GI_low,$ was consistently steeper for CK-SRS compared to
                      SI-VMAT (p < 0.001). CK-SRS achieved a median $GI_high$ of
                      3.1 [interquartile range (IQR), 2.9-1.3] vs. 5.0 (IQR
                      4.3-5.5) for SI-VMAT (p < 0.001). For $GI_low,$ the results
                      were 3.0 (IQR, 2.9-3.1) for CK-SRS vs. 5.6 (IQR, 4.3-5.5)
                      for SI-VMAT (p < 0.001). The median conformity index (CI)
                      was 1.2 (IQR, 1.1-1.2) for CK-SRS vs. 1.5 (IQR, 1.4-1.7) for
                      SI-VMAT (p < 0.001). Estimated treatment time was shorter
                      for SI-VMAT, yielding a median of 13.7 min (IQR, 13.5-14.0)
                      compared to 130 min (IQR, 114.5-154.5) for CK-SRS (p <
                      0.001). Conclusion: SI-VMAT offers enhanced treatment
                      efficiency in cases with multiple BM, as compared to
                      CyberKnife, but requires compromise regarding conformity and
                      integral dose to the healthy brain. Additionally, delivery
                      at a conventional linear accelerator (linac) may require a
                      larger PTV margin to account for delivery and setup errors.
                      Further evaluations are warranted to determine whether the
                      detected dosimetric differences are clinically relevant.
                      SI-VMAT could be a reasonable alternative to a dedicated
                      radiosurgery system for selected patients with multiple BM.},
      cin          = {E050 / HD01},
      ddc          = {610},
      cid          = {I:(DE-He78)E050-20160331 / I:(DE-He78)HD01-20160331},
      pnm          = {315 - Imaging and radiooncology (POF3-315)},
      pid          = {G:(DE-HGF)POF3-315},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:32457829},
      pmc          = {pmc:PMC7225280},
      doi          = {10.3389/fonc.2020.00568},
      url          = {https://inrepo02.dkfz.de/record/157092},
}