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@ARTICLE{Weidner:178646,
      author       = {A. Weidner$^*$ and C. Stengl$^*$ and F. Dinkel$^*$ and S.
                      Dorsch$^*$ and C. Murillo$^*$ and S. Seeber$^*$ and R.
                      Gnirs$^*$ and A. Runz$^*$ and G. Echner$^*$ and C. P.
                      Karger$^*$ and O. Jaekel$^*$},
      title        = {{A}n abdominal phantom with anthropomorphic organ motion
                      and multimodal imaging contrast for {MR}-guided
                      radiotherapy.},
      journal      = {Physics in medicine and biology},
      volume       = {67},
      number       = {4},
      issn         = {0031-9155},
      address      = {Bristol},
      publisher    = {IOP Publ.},
      reportid     = {DKFZ-2022-00175},
      pages        = {045009},
      year         = {2022},
      note         = {#EA:E040#LA:E040# / 2022 Feb 11;67(4) 045009},
      abstract     = {Improvements in image-guided-radiotherapy (IGRT) enable
                      accurate and precise radiotherapy treatments of moving
                      tumors in the abdomen while simultaneously sparing healthy
                      tissue. However, the lack of validation tools for newly
                      developed IGRT hybrid devices such as MR-Linac is an open
                      issue. This study presents an abdominal phantom with
                      respiratory organ motion and multimodal imaging contrast to
                      perform end-to-end tests in IGRT. The abdominal phantom
                      contains anatomically shaped liver and kidney models made of
                      Ni-DTPA and KCl-doped agarose mixtures that can be
                      reproducibly positioned within the phantom. Organ models are
                      wrapped in foil to avoid ion exchange with the surrounding
                      agarose-based fatty tissue and to allow stable imaging
                      contrast. Breathing motion is realized by a diaphragm
                      connected to an actuator that is hydraulically controlled
                      via a programmable logic controller (PLC). With this system,
                      artificial and patient-specific breathing patterns can be
                      carried out. In 1.5 and 3 T magnetic resonance imaging (MRI)
                      and computed tomography (CT) series, diaphragm, liver and
                      kidney motion was measured and compared to the breathing
                      motion of a healthy male volunteer for different breathing
                      amplitudes including shallow, normal and deep breathing. The
                      constructed abdominal phantom demonstrated tissue-equivalent
                      contrast in CT as well as in MRI. T1-weighted (T1w) and
                      T2-weighted (T2w) relaxation times and CT-numbers were 552.9
                      ms, 48.2 ms and 48.8 HU (liver) and 950.42 ms, 79 ms and
                      28.2 HU (kidney), respectively. These values were stable for
                      more than one month. Extracted breathing motion from a
                      healthy volunteer revealed a liver to diaphragm motion ratio
                      (LDMR) of 64.4 $\%$ and a kidney to diaphragm motion ratio
                      (KDMR) of 30.7 $\%.$ Well-comparable values were obtained
                      for the phantom (LDMR: 65.5 $\%,$ KDMR: 27.5 $\%).$ The
                      abdominal phantom demonstrated anthropomorphic imaging
                      contrast and physiological motion pattern in MRI and CT.
                      This allows for wide use in the validation of IGRT.},
      keywords     = {Abdominal breathing phantom (Other) / Image-guided
                      radiotherapy (Other) / anthropomorphic image contrast
                      (Other) / intrafractional breathing motion (Other) /
                      magnetic resonance-guided radiotherapy (Other)},
      cin          = {E040 / E010},
      ddc          = {530},
      cid          = {I:(DE-He78)E040-20160331 / I:(DE-He78)E010-20160331},
      pnm          = {315 - Bildgebung und Radioonkologie (POF4-315)},
      pid          = {G:(DE-HGF)POF4-315},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:35081516},
      doi          = {10.1088/1361-6560/ac4ef8},
      url          = {https://inrepo02.dkfz.de/record/178646},
}