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@ARTICLE{Qubala:307464,
      author       = {A. Qubala and C. P. Karger$^*$ and J. Horn and M. Winter
                      and M. Ellerbrock and O. Jäkel$^*$ and K. Henkner},
      title        = {{P}atient-specific quality assurance at the {H}eidelberg
                      {I}on {B}eam {T}herapy {C}enter: 10 years experience in
                      treatment plan verification.},
      journal      = {Medical physics},
      volume       = {53},
      number       = {1},
      issn         = {0094-2405},
      address      = {Hoboken, NJ},
      publisher    = {Wiley},
      reportid     = {DKFZ-2025-03063},
      pages        = {e70237},
      year         = {2026},
      abstract     = {To ensure accurate, safe, and reproducible patient
                      treatments, it is essential to have precise knowledge and a
                      solid understanding of patient-specific quality assurance
                      (PSQA). For many years, the delivery of doses to all
                      patients has been verified using dosimetric measurements.
                      However, these measurements require substantial work, and
                      the reasons for the occasional deviations are unclear. For
                      these reasons, alternative methods such as independent dose
                      calculations (IDCs) and analysis of beam-monitor log files
                      are increasingly discussed in the particle therapy
                      community. Nevertheless, before replacing dose-verification
                      measurements with other methods, existing measurement data
                      should be thoroughly analyzed to determine what can be
                      learned from them and how they compare with potential
                      alternatives. These alternative methods are mentioned in
                      this work only to provide context and to outline possible
                      directions for future studies.To evaluate the dosimetric
                      accuracy and efficiency of PSQA using a water phantom (WP)
                      over a 10-year period at the Heidelberg Ion Beam Therapy
                      Center (HIT).Between 2016 and 2025, 23014 treatment fields
                      with protons, carbon, or helium ions were verified using a
                      WP equipped with 24 pinpoint ionization chambers. The
                      patient treatment plans were recalculated in the water
                      phantom geometry and compared to measured absolute doses.
                      The data were categorized by treatment room, ion species,
                      treatment planning systems (TPS), range shifter (RaShi) use,
                      indication, depth, and target volume, excluding measurements
                      with human errors. Statistical analysis compared measured
                      and calculated doses, focusing on mean, maximum, and minimum
                      dose deviations. Furthermore, the workflow efficiency was
                      assessed based on the beam time required for dosimetric
                      verification, as well as the total time needed for
                      preparation and analysis.Mean dose deviations were in
                      general slightly negative (t-test, p < 0.01), within ±1
                      $\%$ across all categories (total mean ± SD = -0.50 ± 0.90
                      $\%),$ with 91 $\%$ of fields passing institutional ±5 $\%$
                      tolerances. Further, significant differences (p < 0.01) were
                      also observed between treatment rooms, ion species, TPS
                      platforms, and RaShi settings. Additionally, the RayStation
                      TPS showed lower deviations than the Syngo TPS, and helium
                      ions had the smallest deviations. Moreover, repeated
                      verifications reduced variability but without significant
                      improvement. Correlations with target depth or volume were
                      statistically significant but clinically negligible. Less
                      than 1 $\%$ of maximum and minimum dose measurements
                      exceeded ±7 $\%$ annually. Finally, over 4308 h of beam
                      time, preparation, and analysis were spent on PSQA during
                      the 10-year period.PSQA at HIT demonstrated high dosimetric
                      accuracy and delivery stability. Integration of IDCs and log
                      file analysis may improve efficiency and allow to omit
                      verification measurements in well-established cases without
                      compromising patient safety and treatment quality, if the
                      extensive machine QA program is maintained.},
      keywords     = {Quality Assurance, Health Care / Humans / Radiotherapy
                      Planning, Computer-Assisted: methods / Heavy Ion
                      Radiotherapy / Time Factors / Radiotherapy Dosage /
                      Phantoms, Imaging / Radiometry / dose measurements (Other) /
                      dose verification (Other) / helium and carbon ion beam
                      therapy (Other) / particle therapy (Other) / patient
                      specific quality assurance (Other) / proton (Other) / spot
                      scanning (Other) / water phantom (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:41452343},
      pmc          = {pmc:PMC12742551},
      doi          = {10.1002/mp.70237},
      url          = {https://inrepo02.dkfz.de/record/307464},
}