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@ARTICLE{Amato:153435,
      author       = {C. Amato$^*$ and M. Martisikova$^*$ and T. Gehrke$^*$},
      title        = {{A} technique for spatial resolution improvement in
                      helium-beam radiography.},
      journal      = {Medical physics},
      volume       = {47},
      number       = {5},
      issn         = {2473-4209},
      address      = {College Park, Md.},
      publisher    = {AAPM},
      reportid     = {DKFZ-2020-00286},
      pages        = {2212-2221},
      year         = {2020},
      note         = {2020 Jun;47(5):2212-2221#EA:E040#LA:E040#},
      abstract     = {Ion-beam radiography exhibits a significantly lower spatial
                      resolution (SR) compared to X-ray radiography. This is
                      mostly due the multiple Coulomb scattering (MCS) that the
                      ions undergo in the imaged object. In this work, a novel
                      technique to improve the spatial resolution in helium-beam
                      radiography was developed. Increasing helium-beam energies
                      were exploited in order to decrease the MCS, and therefore
                      increase the SR.The experimental investigation was carried
                      out with a dedicated ion-tracking imaging system fully
                      composed of thin, pixelated silicon detectors (Timepix).
                      Four helium beams with increasing energies (from 168.8MeV/u
                      to 220.5MeV/u) were used to image a homogeneous 160mm PMMA
                      phantom with a 2mm air gap at middle depth. An energy
                      degrader was placed between the rear tracking system and the
                      energy-deposition detector to compensate for the longer
                      range associated with more energetic ions. The SR was
                      measured for each beam energy. To take into account the
                      overall impact on the image quality, the contrast-to-noise
                      ratio (CNR), the single-ion water equivalent thickness (WET)
                      precision and the absorbed dose in the phantom were also
                      evaluated as a function of the initial beam energy. FLUKA
                      Monte Carlo simulations were used to support the conceptual
                      design of the experimental setup and for dose estimation.In
                      the investigated energy interval, a total SR increase by
                      around $30\%$ was measured with increasing beam energy,
                      reaching a maximum value of 0.69 lp/mm. For radiographs
                      generated with 350 μGy of absorbed dose and 220 μm pixel
                      size, a CNR decrease of $32\%$ was found as the beam energy
                      increases. For 1mm pixel size, the CNR decreases only by
                      $22\%.$ The CNR of the images was always above 6. The
                      single-ion WET precision was found to be in a range between
                      $1.2\%$ and 1.5 $\%.We$ have experimentally shown and
                      quantified the possibility of improving SR in helium-beam
                      radiography by using increasing beam energies in combination
                      with an energy degrader. A significant SR increase was
                      measured with an acceptable decrease of CNR. Furthermore, we
                      have shown that an energy degrader can be a valuable tool to
                      exploit increasing beam energies to generate
                      energy-deposition radiographs.},
      cin          = {E040},
      ddc          = {610},
      cid          = {I:(DE-He78)E040-20160331},
      pnm          = {315 - Imaging and radiooncology (POF3-315)},
      pid          = {G:(DE-HGF)POF3-315},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:31995641},
      doi          = {10.1002/mp.14051},
      url          = {https://inrepo02.dkfz.de/record/153435},
}