% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@ARTICLE{Schmidt:309814,
      author       = {S. Schmidt$^*$ and I. D. Muñoz$^*$ and E. G. Yukihara and
                      J. A. Vedelago$^*$},
      title        = {{F}luorescent nuclear track detectors for out-of-field
                      neutron dosimetry in proton therapy.},
      journal      = {Medical physics},
      volume       = {53},
      number       = {2},
      issn         = {0094-2405},
      address      = {Hoboken, NJ},
      publisher    = {Wiley},
      reportid     = {DKFZ-2026-00324},
      pages        = {e70303},
      year         = {2026},
      note         = {#EA:E040#LA:E040#},
      abstract     = {Secondary neutrons are a major concern regarding side
                      effects in ion beam therapy because they contribute to the
                      out-of-field dose, particularly important for sensitive
                      patient groups such as pregnant and pediatric patients.
                      Measuring these neutrons is challenging because of their
                      high kinetic energy, which is imparted to charged particles
                      like fragments and recoil protons. In addition, accurate
                      measurements require small detectors that ideally do not
                      disturb the radiation field when measuring inside a phantom.
                      Fluorescent Nuclear Track Detectors (FNTDs) have already
                      shown promising results in ion beam dosimetry and the
                      measurement in fast neutron fields. Given their high spatial
                      resolution and sensitivity, FNTDs offer a promising approach
                      for characterizing secondary neutron doses in complex
                      radiation environments, such as those encountered in proton
                      therapy.Establish a methodology for estimating
                      neutron-induced out-of-field dose inside a phantom. The
                      focus is to discuss the technical requirements and present
                      initial experimental results from a proton treatment
                      plan.The analysis workflow for determining dose equivalent
                      with FNTDs is introduced, including intensity-to-linear
                      energy transfer (LET) in water conversion and track polar
                      angle corrections. FNTDs were placed inside RW3 and
                      polymethyl methacrylate phantoms and irradiated with a
                      proton spread-out Bragg peak (SOBP) plan. Experimental
                      results from two downstream positions in each phantom were
                      used to benchmark Monte Carlo simulations.A polar angle
                      correction function was established, indicating intensity
                      corrections of approximately a factor of 2 at 20 ∘ $20
                      {^{\circ }}$ and up to a factor of 3.5 beyond 50 ∘ $50
                      {^{\circ }}$ . Furthermore, a few short-range high-LET
                      tracks with a low probability of occurrence have been found.
                      Despite accounting for only about 1 \% $1 \,\\%$ of the
                      total fluence, high-LET tracks can contribute more than 50
                      \% $50 \,\\%$ of the total dose equivalent. When not
                      considering these short-range tracks, the relative agreement
                      in dose equivalent between simulations and experiments was
                      within ( 1.10 ± 0.10 $1.10\nobreakspace \pm \nobreakspace
                      0.10$ ) to ( 1.49 ± 0.13 $1.49\nobreakspace \pm
                      \nobreakspace 0.13$ ).This work presents the first LET-based
                      method using FNTDs to estimate out-of-field neutron dose for
                      a proton SOBP plan, measured inside a phantom. Integrating
                      this method into clinical workflows may improve out-of-field
                      dose estimation for sensitive patient groups, such as
                      pregnant or pediatric patients, by enabling prior dose
                      assessments using anthropomorphic phantoms.},
      keywords     = {Neutrons / Proton Therapy / Radiometry: instrumentation /
                      Monte Carlo Method / Phantoms, Imaging / Fluorescence /
                      Radiotherapy Dosage / Linear Energy Transfer / fluorescent
                      nuclear track detectors (Other) / neutron dosimetry (Other)
                      / proton out‐of‐field measurements (Other)},
      cin          = {E040},
      ddc          = {610},
      cid          = {I:(DE-He78)E040-20160331},
      pnm          = {315 - Bildgebung und Radioonkologie (POF4-315)},
      pid          = {G:(DE-HGF)POF4-315},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:41665521},
      doi          = {10.1002/mp.70303},
      url          = {https://inrepo02.dkfz.de/record/309814},
}