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@ARTICLE{Fullarton:358296,
      author       = {Fullarton, Ryan and Simard, Mikaël and Volz, Lennart and
                      Toltz, Allison and Chung, Savanna and Schuy, Christoph and
                      Robertson, Daniel G. and Royle, Gary and Beddar, Sam and
                      Baker, Colin and Graeff, Christian and Collins-Fekete,
                      Charles-Antoine},
      title        = {{I}maging lung tumor motion using integrated‐mode proton
                      radiography—{A} phantom study towards tumor tracking in
                      proton radiotherapy},
      journal      = {Medical physics},
      volume       = {52},
      number       = {2},
      issn         = {0094-2405},
      address      = {Hoboken, NJ},
      publisher    = {Wiley},
      reportid     = {GSI-2025-00500},
      pages        = {1146 - 1158},
      year         = {2025},
      note         = {his is an open access article under the terms of the
                      Creative Commons Attribution License 4},
      abstract     = {Motion of lung tumors during radiotherapy leads to
                      decreased accuracy of the delivered dose distribution. This
                      is especially true for proton radiotherapy due to the finite
                      range of the proton beam. Methods for mitigating motion rely
                      on knowing the position of the tumor during treatment.Proton
                      radiography uses the treatment beam, at an energy high
                      enough to traverse the patient, to produce a radiograph.
                      This work shows the first results of using an
                      integrated-mode proton radiography system to track the
                      position of moving objects in an experimental phantom study;
                      demonstrating the potential of using this method for
                      measuring tumor motion.Proton radiographs of an
                      anthropomorphic lung phantom, with a motor-driven tumor
                      insert, were acquired approximately every 1 s, using tumor
                      inserts of 10, 20, and 30 mm undergoing a known periodic
                      motion. The proton radiography system used a monolithic
                      scintillator block and digital cameras to capture the
                      residual range of each pencil beam passing through the
                      phantom. These ranges were then used to produce a water
                      equivalent thickness map of the phantom. The centroid of the
                      tumor insert in the radiographs was used to determine its
                      position. This measured position was then compared to the
                      known motion of the phantom to determine the
                      accuracy.Submillimeter accuracy on the measurement of the
                      tumor insert was achieved when using a 30 mm tumor insert
                      with a period of 24 s and was found to be improved for
                      decreasing motion amplitudes with a mean absolute error
                      (MAE) of 1.0, 0.9, and 0.7 mm for 20, 15, and 10 mm
                      respectively. Using smaller tumor inserts reduced the
                      accuracy with a MAE of 1.8 and 1.9 mm for a 20 and 10 mm
                      insert respectively undergoing a periodic motion with an
                      amplitude of 20 mm and a period of 24 s. Using a shorter
                      period resulted in significant motion artifacts reducing the
                      accuracy to a MAE of 2.2 mm for a 12 s period and 3.1 mm for
                      a 6 s period for the 30 mm insert with an amplitude of 20
                      mm.This work demonstrates that the position of a lung tumor
                      insert in a realistic anthropomorphic phantom can be
                      measured with high accuracy using proton radiographs.
                      Results show that the accuracy of the position measurement
                      is the highest for slower tumor motions due to a reduction
                      in motion artifacts. This indicates that the primary
                      obstacle to accurate measurement is the speed of the
                      radiograph acquisition. Although the slower tumor motions
                      used in this study are not clinically realistic, this work
                      demonstrates the potential for using proton radiography for
                      measuring tumor motion with an increased scanning speed that
                      results in a decreased acquisition time.},
      keywords     = {Phantoms, Imaging / Lung Neoplasms: radiotherapy / Lung
                      Neoplasms: diagnostic imaging / Proton Therapy: methods /
                      Humans / Movement / Radiotherapy, Image-Guided: methods /
                      Radiotherapy, Image-Guided: instrumentation / Radiography /
                      interplay effect (Other) / intrafraction motion (Other) /
                      proton radiography (Other)},
      cin          = {BIO},
      ddc          = {610},
      cid          = {I:(DE-Ds200)BIO-20160831OR354},
      pnm          = {633 - Life Sciences – Building Blocks of Life: Structure
                      and Function (POF4-633) / HITRIplus - Heavy Ion Therapy
                      Research Integration plus (101008548)},
      pid          = {G:(DE-HGF)POF4-633 / G:(EU-Grant)101008548},
      experiment   = {$EXP:(DE-Ds200)External_experiment-20200803$},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:39530503},
      UT           = {WOS:001354151200001},
      doi          = {10.1002/mp.17508},
      url          = {https://repository.gsi.de/record/358296},
}