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@INPROCEEDINGS{Petrich:1026458,
      author       = {Petrich, C. and Dimroth, A. and Kraus, K. M. and Winter, J.
                      and Matejcek, C. and Butzek, M. and Natour, G. and
                      Ravichandran, M. and Zimmermann, M. and Aulenbacher, K. and
                      Galek, M. and Wilkens, J. and Combs, S. E. and Bartzsch, S.},
      title        = {{T}owards {C}linical {T}ranslation of {M}icrobeam
                      {R}adiation {T}herapy ({MRT}) with a {C}ompact {S}ource},
      issn         = {0360-3016},
      reportid     = {FZJ-2024-03407},
      year         = {2023},
      abstract     = {Purpose/Objective(s)MRT is an innovative concept of
                      spatially fractionated radiation therapy that has
                      demonstrated substantially improved normal tissue tolerance
                      while achieving local tumor control in a wealth of
                      preclinical studies. In MRT a collimator shapes a few
                      micrometers wide planar x-ray beams with a spacing of a few
                      100 µm. MRT has the potential to improve cancer treatment
                      substantially. However, until now, only a few large 3rd
                      generation synchrotrons provide beam parameters that would
                      allow patient treatments and therefore, MRT has not yet
                      become clinically available. For a clinical translation,
                      compact x-ray sources are required, that produce high dose
                      rate orthovoltage x-rays from a micrometer sized
                      emitter.Materials/MethodsWe developed and built a first
                      prototype of a line focus x-ray tube (LFxT) dedicated to
                      preclinical MRT research. By exploiting the heat capacity
                      limit, the LFxT can deliver dose rates above 100 Gy/s from a
                      just 50 µm-wide focal spot without destroying the rapidly
                      (>200 Hz) rotating x-ray target. A bespoke collimator splits
                      the homogeneous x-ray field into 50 µm wide high-dose peaks
                      separated by 350 µm wide low-dose troughs (valleys). While
                      the prototype in our lab is restricted to a power of 90 kW
                      and 10 Gy/s at 300 kVp, we have started the development of
                      the first clinically usable LFxT-2 at 1.5 MW power and >100
                      Gy/s at 600 kVp beam quality. We investigated the clinical
                      applicability of the LFxT-2 by performing retrospective
                      treatment planning studies. In particular, we were
                      examining, whether 600 kVp photons would suffice to meet
                      clinical dose constraints in MRT treatments treatment
                      scenarios for first clinical use of MRT. We coupled the open
                      source platform 3D Slicer with an in-house developed dose
                      calculation algorithm for MRT treatment planning. For
                      comparability of spatially fractionated MRT doses with
                      conventional broad beam treatments, the MRT dose was
                      converted to equivalent uniform dose (EUD) and equivalent
                      doses in 2-Gy-fractions (EQD2). The 3D Slicer RT toolkit
                      enabled the dosimetric analysis based on dose volume
                      histograms (DVHs).ResultsWe installed a preclinical
                      prototype of the LFxT that is currently put into operation
                      and commissioned. Simulations show the feasibility of the
                      next generation LFxT-2 with more than 100 Gy/s peak dose
                      rate. Planned MRT dose distributions with the LFxT-2 meet
                      established radiotherapy dose constraints in many of the
                      investigated clinical cases. However, treatment planning
                      procedures are not yet optimal and require
                      improvement.ConclusionIn a next step, we will build the
                      LFxT-2 and aim for first clinical MRT trials at this source.
                      In order to further improve calculated MRT dose
                      distributions, we will implement inverse treatment planning
                      techniques.},
      month         = {Sep},
      date          = {2023-09-27},
      organization  = {54. Jahrestagung der Deutschen
                       Gesellschaft für Medizinphysik,
                       Magdeburg (Germany), 27 Sep 2023 - 30
                       Sep 2023},
      cin          = {ZEA-1 / ICE-3},
      ddc          = {610},
      cid          = {I:(DE-Juel1)ZEA-1-20090406 / I:(DE-Juel1)ICE-3-20101013},
      pnm          = {5241 - Molecular Information Processing in Cellular Systems
                      (POF4-524) / DFG project 416790481 - Tumortherapie mit
                      Mikrostrahlen an kompakter Strahlenquelle (416790481)},
      pid          = {G:(DE-HGF)POF4-5241 / G:(GEPRIS)416790481},
      typ          = {PUB:(DE-HGF)1},
      doi          = {10.1016/j.ijrobp.2023.06.308},
      url          = {https://juser.fz-juelich.de/record/1026458},
}