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@ARTICLE{FlixBautista:294438,
      author       = {R. Félix-Bautista$^*$ and L. Ghesquiere-Dierickx$^*$ and
                      P. Ochoa-Parra$^*$ and L. Kelleter$^*$ and G. Echner$^*$ and
                      J. Debus and O. Jäkel$^*$ and M. Martišíková$^*$ and T.
                      Gehrke$^*$},
      title        = {{I}nhomogeneity detection within a head-sized phantom using
                      tracking of charged nuclear fragments in ion beam therapy.},
      journal      = {Physics in medicine and biology},
      volume       = {69},
      number       = {22},
      issn         = {0031-9155},
      address      = {Bristol},
      publisher    = {IOP Publ.},
      reportid     = {DKFZ-2024-02263},
      pages        = {225003},
      year         = {2024},
      note         = {#EA:E040#LA:E040#},
      abstract     = {Objective.The highly conformal carbon-ion radiotherapy is
                      associated with an increased sensitivity of the dose
                      distributions to internal changes in the patient during the
                      treatment course. Hence, monitoring methodologies capable of
                      detecting such changes are of vital importance. We
                      established experimental setup conditions to address the
                      sensitivity of a monitoring approach based on
                      secondary-fragment tracking for detecting clinically
                      motivated air cavity dimensions in a homogeneous head-sized
                      PMMA phantom in 40 mm depth.Approach.The air cavities were
                      positioned within the entrance channel of a treatment field
                      of 50 mm diameter at three lateral positions. The measured
                      secondary-fragment emission profiles were compared to a
                      reference measurement without cavities. The experiments were
                      conducted at the Heidelberg Ion-Beam Therapy Center in
                      Germany at typical doses and dose rates.Main
                      results.Significances above a detectability threshold of
                      2σfor the larger cavities (20 mm diameter and 4 mm
                      thickness, and 20 mm diameter and 2 mm thickness) across the
                      entire treatment field. The smallest cavity of 10 mm
                      diameter and 2 mm thickness, which is on the lower limit of
                      clinical interest, could not be detected at any position. We
                      also demonstrated that it is feasible to reconstruct the
                      lateral position of the cavity on average within 2.8 mm,
                      once the cavity is detected. This is sufficient for the
                      clinicians to estimate medical effects of such a cavity and
                      to decide about the need for a control imaging
                      CT.Significance.This investigation defines well-controlled
                      reference conditions for the evaluation of the performance
                      of any kind of treatment monitoring method and its
                      capability to detect internal changes within head-sized
                      objects. Four air cavities with volumes between 0.31 cm3and
                      1.26 cm3were narrowed down around the detectability
                      threshold of this secondary-fragment-based monitoring
                      method.},
      keywords     = {Phantoms, Imaging / Humans / Heavy Ion Radiotherapy / Head:
                      diagnostic imaging / Radiotherapy Dosage / Timepix3 (Other)
                      / carbon-ion radiotherapy (Other) / inter-fractional changes
                      (Other) / non-invasive treatment monitoring (Other) /
                      nuclear fragmentation (Other) / silicon pixel detector
                      (Other) / single fragment tracking (Other)},
      cin          = {E040},
      ddc          = {530},
      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:39422080},
      doi          = {10.1088/1361-6560/ad8870},
      url          = {https://inrepo02.dkfz.de/record/294438},
}