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@ARTICLE{Loukiala:12015,
      author       = {Loukiala, A. and Tuna, U. and Beer, S. and Jahnke, S. and
                      Ruotsalainen, U.},
      title        = {{G}ap-filling methods for 3{D} {P}lan{TIS} data},
      journal      = {Physics in medicine and biology},
      volume       = {55},
      issn         = {0031-9155},
      address      = {Bristol},
      publisher    = {IOP Publ.},
      reportid     = {PreJuSER-12015},
      pages        = {6125 - 6139},
      year         = {2010},
      note         = {The authors thank Dr Gerhard Roeb and Marco Dautzenberg for
                      assistance with the phantom studies. This work was supported
                      by the Academy of Finland (application number 129657,
                      Finnish Programme for Centres of Excellence in Research
                      2006-2011) and by the Graduate School in Electronics,
                      Telecommunication and Automation (GETA), Finland. This work
                      was partly funded by Forschungszentrum Julich, Germany.},
      abstract     = {The range of positron emitters and their labeled compounds
                      have led to high-resolution PET scanners becoming widely
                      used, not only in clinical and pre-clinical studies but also
                      in plant studies. A high-resolution PET scanner, plant
                      tomographic imaging system (PlanTIS), was designed to study
                      metabolic and physiological functions of plants
                      noninvasively. The gantry of the PlanTIS scanner has
                      detector-free regions. Even when the gantry of the PlanTIS
                      is rotated during the scan, these regions result in missing
                      sinogram bins in the acquired data. Missing data need to be
                      estimated prior to the analytical image reconstructions in
                      order to avoid artifacts in the final reconstructed images.
                      In this study, we propose three gap-filling methods for
                      estimation of the unique gaps existing in the 3D PlanTIS
                      sinogram data. The 3D sinogram data were gap-filled either
                      by linear interpolation in the transaxial planes or by the
                      bicubic interpolation method (proposed for the ECAT
                      high-resolution research tomograph) in the transradial
                      planes or by the inpainting method in the transangular
                      planes. Each gap-filling method independently compensates
                      for slices in one of three orthogonal sinogram planes
                      (transaxial, transradial and transangular planes). A 3D
                      numerical Shepp-Logan phantom and the NEMA image quality
                      phantom were used to evaluate the methods. The gap-filled
                      sinograms were reconstructed using the analytical 3D
                      reprojection (3DRP) method. The NEMA phantom sinograms were
                      also reconstructed by the iterative reconstruction method,
                      ordered subsets maximum a posteriori one step late
                      (OSMAPOSL), to compare the results of gap filling followed
                      by 3DRP with the results of OSMAPOSL reconstruction without
                      gap filling. The three methods were evaluated quantitatively
                      (by mean square error and coefficients of variation) over
                      the selected regions of the 3D numerical Shepp-Logan phantom
                      at eight different Poisson noise levels. Moreover, the NEMA
                      phantom scan data were used in visual assessments of the
                      methods. We observed that all methods improved the
                      reconstructed images both quantitatively and visually.
                      Therefore, the proposed gap-filling methods followed by the
                      analytical 3DRP are alternative for the reconstructions of
                      not only the 3D PlanTIS data, but also other PET scanner
                      data of the ClearPET family.},
      keywords     = {Imaging, Three-Dimensional: methods / Phantoms, Imaging /
                      Plant Physiological Processes / Plants: metabolism /
                      Positron-Emission Tomography / Tomography: methods / J
                      (WoSType)},
      cin          = {ICG-3 / ZEL},
      ddc          = {570},
      cid          = {I:(DE-Juel1)ICG-3-20090406 / I:(DE-Juel1)ZEL-20090406},
      pnm          = {Terrestrische Umwelt},
      pid          = {G:(DE-Juel1)FUEK407},
      shelfmark    = {Engineering, Biomedical / Radiology, Nuclear Medicine $\&$
                      Medical Imaging},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:20871138},
      UT           = {WOS:000282599000006},
      doi          = {10.1088/0031-9155/55/20/006},
      url          = {https://juser.fz-juelich.de/record/12015},
}