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@ARTICLE{Oehmigen:873935,
      author       = {Oehmigen, Mark and Lindemann, Maike E. and Tellmann, Lutz
                      and Lanz, Titus and Quick, Harald H.},
      title        = {{I}mproving the {CT} (140 k{V}p) to {PET} (511 ke{V})
                      conversion in {PET}/{MR} {H}ardware {C}omponent
                      {A}ttenuation {C}orrection},
      journal      = {Medical physics},
      volume       = {47},
      number       = {5},
      issn         = {2473-4209},
      address      = {College Park, Md.},
      publisher    = {AAPM},
      reportid     = {FZJ-2020-01108},
      pages        = {2116-2127},
      year         = {2020},
      abstract     = {PurposeToday, attenuation correction (AC) of positron
                      emission tomography/magnetic resonance (PET/MR) hardware
                      components is performed by using an established method from
                      PET/CT hybrid imaging. As shown in previous studies, the
                      established mathematical conversion from computed tomography
                      (CT) to PET attenuation coefficients may, however, lead to
                      incorrect results in PET quantification when applied to AC
                      of hardware components in PET/MR. The purpose of this study
                      is to systematically investigate the attenuating properties
                      of various materials and electronic components frequently
                      used in the context of PET/MR hybrid imaging. The study,
                      thus, aims at improving hardware component attenuation
                      correction in PET/MR.Materials and methodsOverall, 38
                      different material samples were collected; a modular phantom
                      was used to for CT, PET, and PET/MR scanning of all samples.
                      Computed tomography‐scans were acquired with a tube
                      voltage of 140 kVp to determine Hounsfield Units (HU). PET
                      transmission scans were performed with 511 keV to determine
                      linear attenuation coefficients (LAC) of all materials. The
                      attenuation coefficients were plotted to obtain a HU to LAC
                      correlation graph, which was then compared to two
                      established conversions from literature. Hardware
                      attenuation maps of the different materials were created and
                      applied to PET data reconstruction following a phantom
                      validation experiment. From these measurements, PET
                      difference maps were calculated to validate and compare all
                      three conversion methods.ResultsFor each material, the HU
                      and corresponding LAC could be determined and a bi‐linear
                      HU to LAC conversion graph was derived. The corresponding
                      equation was
                      urn:x-wiley:00942405:media:mp14091:mp14091-math-0001 . While
                      the two established conversions lead to a mean
                      quantification PET bias of $4.69\%$ ± $0.27\%$ and
                      $−2.84\%$ ± $0.72\%$ in a phantom experiment, PET
                      difference measurements revealed only 0.5 $\%$ bias in PET
                      quantification when applying the new conversion resulting
                      from this study.ConclusionsAn optimized method for the
                      conversion of CT to PET attenuation coefficients has been
                      derived by systematic measurement of 38 different materials.
                      In contrast to established methods, the new conversion also
                      considers highly attenuating materials, thus improving
                      attenuation correction of hardware components in PET/MR
                      hybrid imaging.},
      cin          = {INM-4},
      ddc          = {610},
      cid          = {I:(DE-Juel1)INM-4-20090406},
      pnm          = {573 - Neuroimaging (POF3-573)},
      pid          = {G:(DE-HGF)POF3-573},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:32052469},
      UT           = {WOS:000535687600014},
      doi          = {10.1002/mp.14091},
      url          = {https://juser.fz-juelich.de/record/873935},
}